NINTH
TARGET FABRICATION SPECIALISTS' MEETING
CONFERENCE PROCEEDINGS
JULY 6-8,1993 MONTEREY, CALIFORNIA a- i^ffk ;
DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED Ninth Target Fabrication Specialists Meeting July 6-8,1993 Lawrence Livermore National Laboratory AGENDA
MONDAY. TULY 5.1993
4:00-8:00pm Registration (Hyatt Hotel, Pebble Room)
TUESDAY, TULY 6.1993
8:00 Registration (Glasgow Hall, Building 302, Room 102)
8:30 Opening Remarks - Tom Bernat
Morning Session - CLASSIFIED* - Russell Wallace - Chairman
8:50 PlastiGeraldc CylindeRivera, LANLr Implosio n Experiment* 9:10 Surface Perturbations of ICF Capsules by Laser Ablation*' Russell Wallace, LLNL
9:30 Unusual Surface Aging of Brominated Plasma Polymer Films*' Evelyn Fearon, LLNL
9:50 Challenges in Spectroscopic Characterization of Hohlraum Environment with Micro-Dot* Ed Hsieh/Tina Back, LLNL
10:10-10:30 BREAK
10:30 FabricatioPete Gobby,n anLANLd Characterizatio n of Niobium Opacity Samples* 10:50 The Development and Assembly of the Shear Mix Target* Larry Foreman for Veronica M. Gomez, LANL
% 11:10 Nova Target Design Systematics Via Spectroscopy* Tom Dittrich, Invited Speaker, LLNL
11:40 Experiments on Nova* Richard Ward, Invited Speaker, LLNL
12:10 Nova Target Fabrication for Defense Sciences* Hedley Louis, Invited Speaker, LLNL
Updated: August 18,1993 WEPNESPAY 7/7/93 (continued) 12:40-1:40 LUNCH
Afternoon Session - Steven Letts. Chairman
1:40 Capabilities of the ICP Target Fabrication Support Contractor Ken Schultz, General Atomics
2:00 The Fabrication of Cylindrical Foam Filled Targets Containing Aluminum Spheres for Sphere Drag Experiments Wigen Nazarov, University of Dundee
2:20 Production and Measurement of Randomly Rough Saran Films for Ablation Front Instability Experiments Tony Tyrrell, Atomic Weapons Establishment
2:40 Foster Abstracts One Minute Oral Presentations per Poster
3:10-5:00 Foster Session I (Spanagel Hall, Building 232, Room 101A/E)
1 Modification of Carbon-Fiber Geometry Using an Oxygen-Plasma Etcher Daniel Brennan, University of Rochester
2 The Etching of Carbon Fibers & Their Use in Producing Point Backlighters Joyce Moore, LANL
3 Free-Standing Foil Fabrication Tom Alberts, W.J. Schafer Associates, Inc.
4 Polymer Film Thickness Measurement by FTIR Wayne Bongianni, LANL
5 Techniques for Producing Free-Standing Thin Films on Frames Frere McNamara, Sandia National Lab-Albuquerque
6 Fabrication of Thin Planar Discs for Use in Long-Scale-Length Plasma Experiments Daniel Brennan for Stephen Noyes, University of Rochester
7 Plastic Disc Fabrication for AWE Experiment Leander Salzer, LANL
8 Forming Electrodes for EDM Small Hole Drilling Leander Salzer, LANL
9 Sputter Polymer Films for Target Applications Ed Pierce, LLNL
10 Considerations in the Analysis of X-Ray Fluorescence Data of Au:Gd Foils Bob Turner, LLNL
-2- TUESDAY 7/6/93 (continued)
11 Synthesis and Characterization of 350nm UV Absorbing Barrier Materials Barry McQuillan, General Atomics
12 Precision Electroformed Neutron Penumbral Imaging Apertures Norman Elliott, LANL
13 Lithium Thermal Targets Shot on PBFAII Jim Aubertfor Patricia Sawyer, Sandia National Lab-Albuquerque
14 Hot Box Design for a Barrier Layer Coating Tower Lloyd Brown, General Atomics
15 The Effect of Process Conditions on Plasma Polymer Surface Finish Larry Witt, LLNL
16 Microshell Generation from a Mechanically Vibrated Jet George Overturf, LLNL
6:00-8:00 No host cocktail party with Hors D'oeuvres (La Novia Room in Herrmann Hall, Building 220, downstairs)
-3- Ninth Target Fabrication Specialists Meeting July 6-8,1993 Lawrence Livermore National Laboratory AGENDA
WEDNESDAY. TULY 7.1993
Morning Session - Paul Apen. Chairman
8:00 Announcements, etc. (Glasgow Hall, Building 302, Room 102)
8:10 Triiiation of Polymer Target Materials by Isotopic Exchange Robert Ellefson, EG&G
8:30 Athena Pulse Power Experiments Wallace Anderson, LANL
8:50 Doped Mandrel Production and Characterization at LLNL Bob Cook, LLNL
9:10 Preparation of Hollow Shells Using a Depolymerizing Mandrel Steve Letts, LLNL
9:30 Production of Polymer Shells by Controlled-Mass Microencapsulation Don Nelson, Soane Technology
9:50 Modeling of Microencapsulation Don Nelson, Soane Technology
10:10-10:30 BREAK
10:30 Fabrication of Ablator-Layer-Overcoated Foam Shells at Osaka University Hyo-gun Kim, University of Rochester
10:50 Relating Defects in Plasma-Deposited Coatings to Irregularities on Spherical Substrates Janet Ankney, General Atomics
11:10 Understanding Plasma Polymer Deposition Across Different Coater Platforms Ray Brusasco, LLNL
11:30 The Effects of Substrate Temperature on Plasma Polymer Coatings Mike Saculla, LLNL
11:50 Charged Liquid Cluster Beam Deposition & Possible Application to ICF Target Research Kyekyoon (Kevin) Kim, Univerclty of Illinois
12:10 Recent Progress in the U.S. Inertial Confinement Fusion Program Marshall Sluyter, Invited Speaker, DOE (Presented by Kevin Bieg)
-4- WEDNESDAY 7/7/93 (continued)
12:30-1:30 LUNCH
Afternoon Session - Mark Wittman. Chairman
1:30 Ionized Source Beam Deposition as a Novel Technique for Coating ICF Targets & Target Assemblies Kyekyoon (Kevin) Kim, University of Illinois
1:50 AFM Profilometry for Target Capsule Characterization Randall McEachern, LLNL
2:10 The Measurement of Randomly Rough Surfaces in Laser Targets by Confocal Laser Scanning Microscopy Colin Horsfield, Atomic Weapons Establishment
2:30 Poster Abstracts One Minute Oral Presentations per Poster
3:00-5:00 Poster Session II (Spanagel Hall, Building 232, Room 101A/E)
1 Miniature Bouncer For Microsphere Coatings Ricke Behymer, LLNL
2 Range Extension of Interference Wall Thickness Measurements Donald Beighley, General Atomics
3 Surface Characterization by Interferometry Don Bittner, W.J. Schafer Associates, Inc.
4 State-of-the-art Plasma Polymerization Coater for ICF Targets Gary Devine, LLNL
5 Generating Rough Surfaces on Capsules by Polymer Mist Deposition Steve Buckley, LLNL
6 Chromium Doped Polystyrene for Capsule-Implosion Diagnostics Steve Buckley, LLNL
7 Ball Extractor System for Helical Resonator Coaters Anselmo Duenas, LLNL
8 Production of Microencapsulated Polymer Shells with the Triple-Orifice Controlled Mass System Eben Lilley, Soane Technology
9 Titanium Doping of Polystyrene George Overturf, LLNL
10 Production of Large Polystyrene Shells Ileese Schneir, General Atomics
-5- WEPNESPAY 7/7/93 (continued) 11 An Experimental Design Approach to Microencapsulation Diana Schroen-Carey, W.J. Schnfer Associates, Inc.
12 SEM Analysis • .rget Contamination Caused by Reaction Tube Etching Ed Lindsey, LI.*'
13 A LabVIEW-driven AFM Based Profilometer Craig Moore, LLNL
14 Layering Targets by Microgravity Paul Parks, General Atomics
15 Simplified Fringe Analysis for Wall Thickness Measurements Richard Stephens, General Atomics
16 Rapid Shell Evaluation by Rotating Image Interference Fringe Analysis Richard Stephens, General Atomics
6:00-7:30 No host coctail party 7:00 Banquet and Business Meeting (Ballroom, Herrmann Hall Building 220)
-6- Ninth Target Fabrication Specialists Meeting July 6-8,1993 Lawrence Livermore National Laboratory
AGENDA
THURSDAY. TULY 8.1993
Morning Session - Rich Stephens. Chairman
8:00 Announcements, etc. (Glasgow Hall, Building 302, Room 102)
8:10 ICF Target Characterization Using Index Matching Fluids Dave Steinman, General Atomics
8:30 Computerization of Characterization Richard Stephens, General Atomics
8:50 PVA Layer Characterization Martin Hoppe, General Atomics
9:10 A Destructive Technique for Measuring the Fill of a Fuel Container Mike Saculla, LLNL
9:30 High Resolution Optical Measurements of Bata-Layering in Cylindrical Geometries Jim Hoffer, LANL
9:50 New Polymer Target-Shell Properties and Characterization Amy Honig, Syracuse University
10:10-10:30 BREAK
10:30 Micro-Calorimetry as a Method to ..ieasure Fuel Mass in ICF Capsules Jim Sater, LLNL/W.J. Schafer Associates, Inc.
10:50 Roughness of DT Ice Evan Mapoles, LLNL
-7- WEPNESPAY 7/7/93 (continued)
11:10 A Small Volume Tritium Fill System Mike Salazar, LANL
11:30 Surface Structure of Solid Hydrogen Films Gilbert Collins, LLNL
11:50 Compensation of the Lens Effects of Thick Cryogenic Layers Using an Interferometric Imaging System Mark Wittman, University of Rochester
12:10 Study of Thermal Layering for Millimeter Size Cryogenic ICF Targets Kyekyoon (Kevin) Kim, University of Illinois
12:30-1:30 LUNCH
Afternoon Session - Tim Sater. Chairman
1:30 Liquid H2D2 Layers in Large Capsules Jorge Sanchez, LLNL
1:50 A Simple Model of the Thermal Layering of Cryogenic Deuterium Fuel in an ICF Capsule Michael Monsler, W.J. Schafer Associates, Inc.
2:10 MRI as a Probe of Hydrogen Isotope Fractionation Jim Moore, LLNL
2:30 A Low-Mass Mounting Method for Cryogenic Targets Roger Gram, University of Rochester
-8- PLASTIC CYLINDER IMPLOSION EXPERIMENT. Leander J. Salzer; Gerald Rivera. Elfrno V. Armijo, and Paul G. Apen, Los Alamos National Laboratory, P.O. Box 1663 MS E549, Los Alamos, NM 87545. The fabrication of the plastic cylinders used in recent cylindrical implosion experiments • at NOVA is presented. Seven steps were required - three machining, three coating, and one leaching - for the successful completion of a single cylinder. The coating steps included polystyrene, chlorinated polystyrene and parylene N. Precision machining was required to produce a marker layer as well as a dodecagonal outside surface.
LA-CP-93-118 1
Experiments are needed to study the effects of surface perturbations on Implosions Surface Perturbations of ICF Capsules by Laser Ablation
We want to place Known perturbations on capsule surfaces, and compare the results ot experiments to modelling predictions
We would like both "random bumps" perturbations, and "single mode" perturbations
Can laser pholoablallon techniques micro machine capsules lo produce an appropriate modulated surface for these studies? Russell J. Wallace, Presented to: T. P. Bernal, W.W.Wilcox, Ninth Target Fabrication R. Behymer and S. Manca Specialists Meeting Target Sclance ft Technology llummllinn July 6-8,1993 B3 NMlMalUtMT
•aad
Initial surface perturbations are amplified during the The final Inner perturbation Is calculated from the Implosion, ana move to the luel-pusher Interface pf Initial perturbation using G(n) y
• Mixing the pusher with the fuel cools the fuel drastically, If the final perturbation Isi totoo ' large, the capsule win have no yield. The "mix-depth" (s equal to the ims ot the Inner surface, o
• C0»(ne) -Mllil p«rtutt»Uon AnCottnt) -fliwl p*ituit»Uon n For experimental test of the theory, want o/R to be - 0.1 - 0.4, where R (s the G(n)« : single mode ampllftcatlan (actor, or Gain final inner radius ot the Imploded capsule.
OJ Q{n) G(n) Is calculated from numerical modeling of From the peak ol Gin) (about 3001, this meant Initial Implosions amplitude must be (ess than a taw hundred Angstroms if R Is around 30 • 40 microns
Mod*numb«r-n ! -2B3 5 0
We are examining two options for modifying Multlshot dimpling will only approximate a desired surface structures by laser ablation ^ perturbation by a series of "steps"
IIIHII Multlahol dimpling • "flat-profile" beam • multiple ebot« - beam cross-aecllon changes with each shot
WlljJIW '•«" Single shot "2 - slepi" " - shaped laser beam profile " y "8 -steps" - requires linear rale va. tluence Themak Hepe height tho approximatio* mutt be smaln "goodl enoug" h to
The step approximations don't act like pure Step approximations to pure modes increase single modes g the amplified mix g
flMUlt of Minted sltp amrsikiullon* compared with ampIMM pun imxSm . I - dtp lor Km n • 4 mode (0(4) It 7 J)
i t « « > >• u i« mode number
J-«t»P Even the 2-st»p approximation I-dtp Gift m allows experiments to cover most of tha gain curve with minimal addition to the mix. Tha alep approximations add considerably to tha rms ol the Imploded surface Hod* number 10 PS22 mode growth curve ^ Step approximations to pure modes Increase the amplified mix, but not significantly gj
,2-tl»t>
U>B
• it n » 41 ii u i mode number
Even tlw 2-alep approximation stows experiments to cover most of the gain cum with minimal sddtttontothtmSx.
11 12 PRpPERTIESOF CH PLASMA POLYMER Experimental Setup .H
Exclmer laser (Questek) Gas feed Polymer Wavalenglh 193 nm (ArF) Best depth resolution Trans-2-butina Best surface quality Plaime 308 nm (XeCI) CH, H" -ri Rep rate > 1-50 hz 1 dimple /sec \ / CH, CHg H CH, Puis* energy -100 m) Stability Important ±5% C = C Gas lifetime > 10000 shols / \ .1 III ,
H CH3 Samples CH3CH2 Planer Plasma polymerized coaling (CH) on SI + Hydrogen |-cc-c = c-| Characterization L»ser ablated dimple 1 I I I ' Optical H H CH3 SEM Atomic composition: CHX, 1.2 < x < 1.4 AFM CH Density: 1.0 g/cm3 Rerractive index: 1.6 Color: Yellow (blue absorbing) Iff 01 0683-2024 13 14
SEM micrograph of a CH sample laser ablated utilizing I Initial experiments measured laser ablation rate vs. a contact mask n I fluence B
2000 I «00 • ISFIO -Optfcri ^ I WO o WC SS? «p(M X MOO J 1200 » 1000 1 too fi §00 2 400 zoo 10 100 IKidtt (V^/DT'I)
Ablallon ralefollows Beer' a law Need to operate near threshold
15 16 17
19
Near threshold experiments are consistent with Beer's law.
1004 • MC-lir 'Optical 1100 0 MC-iri -Ottkai 1100 3 1*00 • MMIS -ATM J 1100 2 >oee
? •
J 00
1 19 nmct(aVa«i| Thraihold lluinc* * 30 mj^cm1 Absorption coettlclanl atexIWcm
Incuballon affects appear to be important 22 Current status of LLNL's exclmer laser workstation
All ES&H hurdles overcomel
• Exclmer later operational (Queslett 2B60) • Reliability needs Improvement (Software) Beam characteristics • Modaal beam quality
• Stability i 3.0%
• Exploring optica! bnd sample viewing options
• Sample positioning system on order • 8 axis Requires high positional accuracy
24 Eight axis capsula positioner . g 25 29 Summary
• A "2 step" approximation can be used to study tha effects of surface perturbations on Implosion
Overall gain and conloui approximations require excbner iasar ablation elch rats below a few hundred Anslromi par pulsa
• At 193 nm ablation follows Beer's law with threshold a 30 mf/cm*
Have yet to create required depth with one pulse. At low fluence Incubation Is Important
Profiled beam produced a discontinuity at edge and large scale structure when overlapped
1MB Unusual Surface Aging of Bromine Doped Plasma Polymer Surfaces
E. Fearon, 8. Letts, 8. Buckley, £ Undity, & Moore, II. Secull% W. Ball, R. Cook
Evafyn Faaron Praaanlad lo: Target Science A Technology Ninth Target Fabrication Spadallat tlaattng •ItamwItaM* Montaray, CA BlkMtMWi July 6-8,1M3
Deposition conditions for bromine seeded Bromine doped plasma polymer surfaces plasma polymer change after removal from coater
• Goal: • Outline of talk: - Strata free - Detection - SEM, AFM, dark Held scelterad light - 2 alom% bromine - IdentlflceUon • powder way diffraction - «urfacal1nl(h<10nm RMS - ControKor eliminate) by process • Conditions: - Ga* Hows - Vary flows, pressure, power • Control system contaminants • Tfani-2-bulene, 0.3 seem - Other controls » Hydrogen, 4.0 seem • Overcoat with plain CH • Ethyl bromide, 0.17 aecm - Storage - Pressure: 140 mTorr - Power: 15 watta • Washing surface • OWes us • deposition rata ot 1 .Spmftir
in. —•'«•', When exposed lo air, CHBr coolings grow bumps on the surface Aging bumps were characterized using three forma of microscopy . .
Optical SEU AFU
ftflvaMam*! IIMWMIWSO
ar
N c
»• , V OpUcil i SEH NH.Br bumps were recryalallzed Irom acetone and X-ray diffraction showed that the composition removed by dissolving In water _|r of age bumps was NfyBr-. • ' -* : y • j — . | Action* Wtttt drop pieced on turttct tnd itmo»td BSP-250 (Bumps recrystalllzed on a tlber from s water drop) Observed d spacing (A): 4.06. 2.87. 2.34. 2.03, 1.82, 1.66, 1.44. 1-35, NH4Br (Reagent atandard) lOQM '-. U i Storage conditions and CH overcoating affected aging of bromocarbon films jg. Scattered light Increases as the surface ages. Aging does not return after washing with water. (JL_ i'» n » EJapMdtnt^iJ CH overcoated shell just out of the coater - starting surface finish of the shell AFM Sphere Mapper equatorial acana Power apactnim derived torn B equatorial scene « w us in zn ira us MO CH overcoated shell after 43 days of air storage - the surface has not degraded Conclusion AFM Sphere Mapper equatorial« JLr Power apeclnim derived from 9 equatorial ecana • Surface aging Is NH«Br • Water facilitates growth r i j L . ! • Dry storage prevents growth • Washing with water removes ag!ng bumps I ..35(fr» - Bumps do not return on thin films - 8umpa return on shells • Overcoating with CH prevents grov.ih - on Nats and shells l\ 10 —t---^IC O Work performed under the auspices of the U.S. Department of Energy by Lawrence Uvermore National Laboratory unde Contract W-7405-ENG-48. Ihuuvi «s 10 us :«o as zio us MO CHALLENGES IN SPECTROSCOPIC CHARACTERIZATION OF HOKLRAUM ENVIRONMENT WITH MICRO-DOT* E.T. Hsieh. C.A. Back and M.R. Spragge University of California Lawrence Livermore National Laboratory P.O. Box 808, Livermore, CA 94550 ABSTRACT Spectroscopy can provide measurements that will compliment present research efforts to understand the spot motion, SBS results, and symmetry experiments. The sets of line ratios and line widths from spectroscopic measurements will bracket the temperature and density of the plasma. A MICRO-DOT is a miniature material source, usually in a form of a circular disk approximately 150|i in diameter and a few thousand angstroms thick. When the measurements are carried out in conjunction with the n-dot, a range of possibilities is now open to us. Since the p.-dot can be made of different materials and thicknesses, even temporal and other information can be obtained. The possibilities are only limited by the innovation and capability of target fabrication. Currently, we produce the n.-dots by either evaporation or sputtering through a mask onto a substrate. Different materials, thicknesses and combination of materials have been tried. We use the cut and paste method to place the.^i-dot on the surface. For more advanced applications, the recently perfected inside-out hohlraum fabrication technique will be employed. We will present some of the target configurations and experimental results. * Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-ENG-48. Oral Edmund Hsieh Lawrence Livermore National Lab P.O. Box 808, L-482 Livermore, CA 94550 (510)422-0753 FABRICATION AND CHARACTERIZATION or NIOBIUM OPACITY SAMPLES P.L. Gobby, N.E. Elliott, tf.E Moore, V.M. Gomez, R.C. Cordi and B.F. Henneke. Los Alamos National Laboratory Extended Abstract A variety of techniques have been employed to produce niobium opacity samples for experiments conducted using the NOVA laser at LLNIi. The sample was subject to high temperatures and simultaneously backlit with soft x-rays generated using one or two of the ten NOVA beams. The measurement of the x-ray mass absorption coefficient of the niobium at high temperature is, in fact, its opacity. A sketch of one opacity sample design is shown below. The shaded portions represent the niobium pieces, each one micron thick and 3SO microns wide. The separation between the two niobium strips is 100 microns. The metal strips are fully coated with 6 microns of parylene "N" on each side, with the gap between the metal strips thus having a total parylene thickness of 12 microns. Three techniques used to produce these samples are discussed below. Two of these have produced acceptable opacity samples. The first technique attempted for niobium was identical to that successfully used for silver in previous experiments. In this case a layer of parylene N was first deposited onto a glass slide which had been previously coated with a release layer of polyvinyl alcohol (PVA). Masks for the niobium deposition were formed from flattened pieces of nickel wire (loo microns x 25 microns x 2 mm) which were held in intimate contact to the parylene by strip magnets on the opposite of the glass slide. The niobium deposition was then performed using an electron gun evaporator. Afterwards, the nickel masks were removed and and second parylene coating completed the tamper. Parts were then scored and floated from the slide with water. Unfortunately, niobium•samples produced using this technique were highly stressed and would curl when released from the slide. This had not previously been a problem with the more ductile silver opacity samples. Higher temperature deposition of the niobium may have relieved this stress, but the parylene limited the temperature that could be tolerated. The second technique made use of an existing DC magnetron sputtering system.• The primary difference from the first technique then was in the niobium deposition. The resulting samples were low in stress and laid flat. However, one major change was observed. The samples were semi-transparent. This was attributed to oxidation occurring during the deposition, because niobium is known to be highly reactive and has been used as a getter in vacuum tubes. The experimenters indicated that the oxygen was acceptable, as Ion? as it could be characterized. This characterization first required a niobium film with low oxygen content. This was produced by evaporating niobium directly onto silicon at 10""7 torr with the substrate a few inches from the source. X-ray analysis in the scanning electron microscope indicated the film thus generated was low in oxygen (<5 wt.%), and its niobium areal density was consistent with the physical thickness as measured with a stylus instrument and the bulk density of niobium (8.4 gm/cc) . This film was then used as a standard for subsequent x-ray fluorescence measurements of the opacity samples. When the niobium for the opacity samples was deposited in the sputtering system a quartz crystal was removed from a thickness monitor after "zeroing" the monitor and was placed adjacent to the substrate. This ensured that the subsequent thickness determined from the quartz crystal and that on the substrate were as nearly identical as possible. The measured "thickness" from the crystal monitor was, of course, actually a measure of the total mass areal density. Comparing the total mass areal density thus determined with the niobium areal density as determined from x-ray fluorescence (using our pure niobium standard) thus allowed us to calculate the oxygen content of our opacity samples. This number was typically 20-25%, by weight. Though these samples were used in preliminary experiments at NOVA the high oxygen content was subsequently determined to be undesireable. (Note that pure Nlp^Qs is 30% oxygen by weight.) This leads us to our current technique for the fabrication of niobium samples. Niobium foils were procurred at one micr-.r thickness, suitable for opacity samples. As received, these foils were found to contain approximately 2 wt.% oxygen. Pieces were then cut to the appropriate sub-millimeter size and two were placed on a glass slide separated by 100 microns. This was1' accomplished using at fine brush and water. The slide was then placed in a casting flask and a FQRMVAR film (<1000 Angstroms) was cast ever the slide, including the niobium pieces. This film was then floated free and mounted on a ring. At this point the niobium pieces were suspended in the FORMVAR roughly centered in the ring. The ring was then placed in the parylene coater and both sides of the tamper were deposited at once. After parylene deposition the pieces were cut free. Some curling occasionally occurred, attributed to stresses in the parylene. But heating the samples to 10o degrees Centigrade while being pressed slightly between two glass slides resulted in flat opacity packages. This final technique has worked well. The FORMVAR is in intimate contact with the niobium, and thus no gaps are formed between the niobium and tamper. And since only one parylene coating is necessary, the two sides of the tamper are identical. Further the problems associated with the previous techniques (i.e., curled samples and high oxygen content, respectively) have now been avoided. These samples lay flat and the oxygen content of the rolled foils is less than 5%. THE DEVELOPMENT AND ASSEMBLY OF THE SHEAR MIX TARGET. Veronica M. Gomez, Paul G. Apcn, Hany Bush, Jr., Norman E. Elliott, Peter L. Gobby, Vivian A. Gurule, Joycc E. Moore, and Leander J. Salzer, Los Alamos National Laboratory, P.O. Box 1.663 MS E549, Los Alamos. NM 87545. This poster will show the development and assembly of the Shear Mix Target This target was built for experiments conducted at the HELEN laser at AWE. LA-CP-93-136 NOVA TARGET DESIGN SYSTEMATICA VIA SPECTROSCOPY* T. R. Dittrich, B. A. Hammel, R- McEachem University of California Lawrence Livermore National Laboratory P.O. Box 808. Livermore, CA 94550 ABSTRACT It is now possible to diagnose via spectroscopy the performance of indirectly-driven all-plastic Nova capsules. Described -will be the HEP3 series of capsule implosions which examines the x-ray emission of the argon fuel dopant and the chlorine pusher dopant. This series incorporates target surface characterization gotten from an equatorially tracing atomic force microscope. This spectroscopic technique could be useful for investigating target sensitivities to various design parameters such as capsule size, material compositions and densities and surface characteristics. The technique would also help establish realistic fabrication tolerances on these quantities. * Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-ENG-48. Oral Thomas Dittrich Lawrence livermore National Lab P.O. Box 808, L-477 Livennore, CA 94550 (510)422-4706 Unclassified abstract submitted for oral presentation on Weapons Physics Experiments using ICF facilities at the Ninth Target Fabrication Specialists Meeting Monterey, CA Weapons Physics Experiments on Nova* R. A. Wardt, T. S. Periyf, D. R. Bachf, R. J. Doyast, T. A. Pcyscrf, P. L. Millert, R. C. Caublef, R. W. Leet, B. A. Hammelt, F. Zef. D. W. Philliont, H. N. Komblumt, J. M- Fostert, P. A. Rosenf, R. J. Wallace!, and J. D. Kilkennyt — We have an ongoing series of weapons physics experiments on Nova to study: (i) the transfer of heat by x-rays through ID and 2D geometries, (ii) the opacities of selected elements at various temperatures and densities, (iii) the mixing induced at shocked interfaces between different materials, (iv) low temperature EOS and shock generation, and (v) NLTE radiationtransport . The techniques used to diagnose these experiments as well as the challenging target fabrication requirements will be discussed. A few planned extensions of these initial experiments are also outlined. *Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W- 7405-ENG-48 tLawrence Livermore National Laboratory, P. 0. Box 808, Uvermore, CA 94551, U.S.A. $Atomic Weapons Establishment, Aldermaston, Reading RG74PR, United Kingdom % A paper to be presented at the 9th conference on (CP target fabrication, by Hedley Louis, Mechanical Engineering, Lawrence LJ verm ore National Laboratory. Title: Nova Target Fabrication tor Detensa Sciences Abstract: In the past year at Lawrence Livermore National Laboratoiy, we provided mechanical engineering support In manufacturing arid characterization of Nova targets for Detensa Sciences. The design/experimental physicists used these targets to study nuclear weapons phenomena In the above-ground, laboratory experiments. Nova targets are difficult to manufacture because they are made ol low density and sometimes toxic materials, they have miniature features and they require non-conventional machining techniques and parameters. Taiget fabrication involves engineering analyses, high precision micro-machining and assembly, laser machining, vapor deposition and electroplating. We use the following methods to characterize the targets: metrology, scanning electron microscopy, chemical analyses and a state-of-art technique called Proton Energy Loss. We delivered over 100 targets last year and we expect target fabrication effort to continue at the same level this year. Soon* Tachnetogfei Inc. 4»CENEMl«TOMm» s W i KHW(HU90CWtl>.HHUEfC CAPABILITIES OF THE IDF TARGET »|» e—MtilBIMa Soom rtdndbglM ho. WJ FABRICATION SUPPORT CONTRACTOR' WE MUST FOLLOW THE TASK ORDERING PROCESS • HISTORY • TASK ASSIGNMENTS • Ubtechnical contac t and OA Team tiikfeeder agre e on work desired, • CAPABILITIES AVAILABLE writ* Talk Description. • 'PREVIEW* SOME PAPERS • Ub taehnleat contact submits Taak DaacripUoa to Lab Tergal Manager lor approval and prtoriiluUea KEN SCHULTZ • Ub Target Managera eubadt Task Descriptions to Technical Coordinator GENERAL ATOMICS (BIB Hilch*r) ind DOE (DennU H**Jy). • Tadmleat Coacdhabx and DOE wott with «l I Ub Taqal tlanagm to Ninth Target Fabrication Specialists' Meeting priori Uza and utlgn Teaks. July 6,1993 • OA Ttn earriat Ml Tttks, ta cVou twAota «Kh Lata tacMcal contacts. •Wort tf0M hi (a 11*. D^mainl tfEMtg y mbt ConkKl OfrACO* Iff 1 HO I • Funding tor Tnti coma from QA'a contract; flian ta no coat to fla tabs. ioarjtctnologlntnc. HUS/9- >cowMi«nMics « j iOMUUSOCUfUIC GENERAL ATOMICS IS THE WE ARE DOING 18 TASKS IN FY-93 TARGET SUPPORT CONTRACTOR • Target Research, Development end FebricaUon Support • TEAM: GENERAL ATOMICS (OA), W. J. SCHAFER ASSOCIATES - 8 Taika, 11 paopla (I RE) on-elta at LUA, LANL and 6NL (VUSA). SOME TECHNOLOGIES IHC. (STty • Target Development, Design end Engineering • HISTORY: Contract ivird December 1980 - 3 Talks, tor UNI, NRL and UtVLLC Begin Hailed work l»*y 1SSI Initial* on-ill* support Oeiobor till Proceed without jov»/nmenl equipment December till • Tergal Fabrication Dtvelopmtnl end Production Oellvtt tint tl*t digits to SHI janutiy — 13 Task*, lor UHL, LAIIL, SNL and URflLLE Deliver first compoille polymer cepeulee lo LLNL Hay 1*" — Shell*, Costings, Chwictarbillan, lllcromichlnlng • WE DO ICF TARQET FABRICATION RID, PRODUCTION AND SUPPORT FOR THE S ICF LABORATORIES • 44 Pcopl*, is.aju ^CEKTOUAIUWOr Soon.rechndo0e.lnc. ^»amuiamNKf loan* Tichndogto inc. mnviiuuoauuHUSS-K TARGET RESEARCH, DEVELOPMENT AND TARGET DEVELOPMENT • FABRICATION SUPPORT TASKS AND PRODUCTION CAPABILITY; SHELLS • Pclymtf ihttU • lilt: TnrtPraducta-lMMlKMdntfllM. - iLDMoa'CtwicMatoI* n »• * • ** - Draptamr—LBreaf u wti. uouitiam * tntoMhcpmlaiaaAIMainte JiftWitawUl * iw»mti«« ti^mcu 0 Ufli Dmhp«alelTB»iaiancMafe)i - A titer,* D. Pkbw,' J. Lima - HmnapaMBn-aHcOaa^' TtcMquaaMUMLandUM. D-tdranCaj* * MDtfVJUlitf(U.whlaa£aL • LA02: T«9«flolurtw-l ill Hirfc.UJl.HXHL - tOBorl - CoMMnnaicnanpaMai—BIN * DmfeparierifeariJfll OnnfeTittnMOMLfUft - Ititfat * • UOk OycgMilOmdKMonlUOilUWL - XOaonmdKAkante • Qliii ibatli — L Brown - MftipaMtipla • Ml: MrilapHn^avaM. - T.Mmtt' * tip* rn*Utmlm Uf*m, - Hnaiaaa«nc*hUe«e|M«BB.migi pipHl M Ml * FtBd jrcai*BM.*TBMKW Soon. t^finOog*. he. luuricMgglnkc. Kimmt KUSS. TARGET DEVELOPMENT AND PRODUCTION CAPABILITY: COATINGS DEVELOPMENT, DESIGN AND ENGINEERING TASKS • GDP costing*—J. Ankney* • QAOle — Divilop and maintain tritium capability — 2 GOP cottars In production o(ca?*ulaa — IO9 OA illi license, 2g ICF trillum lab e Paiylenecoatings—ILIleCMUn e NR01 — Oevsiop piscUs Hal targets for NIKE — C. Hsndricks — Production tfconfcnnalcosting s at HMSA — Rif and luiurad CH and cryogenic tirgiti — Precise characterization — photon tunneling microscope • lletala and compounds—IKsm' — Production of ioCv ind flQirvfo r CML — Capjglh to «U» mWI) d sateiMaind e UR61 — Devi)op Urge! deliver) system lo IUI, tayer, characterize and subtta ihstyspumrcoiurs and Ion pWw Inurt ciyogtnle Urgtls for OUEQA-Upgratto - R. Figily — Cryogenic layering* and characterization RID — D. Blttner • Potyimra synthesis—B.UcQuBlin* lapfMliflltiMlrafllAi^f — S)mIfi«jio/doped mddwtan^dpo^mri — Close RtD cooperation: LLNL, LANL, UR/LLE, OA/WJSA — Cryoginlc ijritim inglneiring daalgn and devtlopmint IlipMll^WlMlhl 4>C«nuiinnMCI Soon* rvchnotogfea Inc. MUE9- ' W I •GUFCNAaSOCUIIB.BC COMPUTERIZED CHARACTERIZATION HAS MANY ADVANTAGES // TARGET DEVELOPMENT AND PRODUCTION CAPABILITY: CHARACTERIZATION > i ll Olmenslonal Chuactwlatlon PossMe with Single Mteroscope ODLO-V* • OPTICAL INTERFEROMETRY AT OA, WJSA AND STI «MMctnmls>«0|ia T IM 11 • SEU AT OA AND WJSA AtKMiMncanankk*ili>!K • AFM AT OA • X-RAY AMD IMAGE ANALYSIS BEING INSTALLED AT GA • Us* Friendly for Repid E/ror-frci Oeta ColeeSon — nwcaapuUr • XRF TO BE INSTALLED AT QA IN FY-M • COMPUTERIZED CHARACTERIZATION DEVELOPED FOR PRODUCTION • Seepspora by R Slepftene, a S'jfnmen, CHARACTERIZATION ACCURACY AND EFFICIENCY U. Hoppt and D. Bdghlty • R. STEPHENS, TASK LEADER CBIKUUATOMICS Sooo.fctoobxfihc. ^JMg& / O WJ 4»eweuumM• a femiieMb( TARGET DEVELOPMENT AND PRODUCTION CONTROLLED-MASS MICROENCAPSULATION CAPABILITY: MICROMACHINING • UMIWU-OWWEMOntTOOtEMTt* • CAPABILITY BEING ESTABLISHED AT OA FOR HOHLRAUMS (C) AND TO HIECT MCWEMOlVtHT SOLUTKM AT WJSA FOR PHYSICS PACKAGES (UC) SHEU5 MTO UQISO MVWQ COllftlH • PRECITECH OPTIMUM 3000 MICROUTHE AT OA • IHE11J UP TO I cai CUJKTU HAVE SUN MJECTEO • ROCKY FLATS EQUIPMENT BEINQ TRANSFERRED TO WJSA AND GA • ELECTROPLATING FACILITY SET UP AT GA • SHOUUFTOMCUIcmHAneEBI iuccessfuuv cubed jwo hjuwutio • PRODUCTION CAPABILITY EXPECTED BY SEPTEMBER 1993 • IK MJ>f RS ST SOAME. KE150H 1X0 UUfT • K. SHILUTO, TASK LEADER ^cwuiamHn MICROENCAPSULATION OPTIMIZATION THE GA/WJSA/STI TEAM SUPPORTS FOR LARGE SHELLS • THE ICF LABS • statistical cheimtrv oPTmiunoH PROVma * UETHOO FOR MIOCESS • ICF TARGET RESEARCH, DEVELOPMENT AND PRODUCTION IMPROVEMENT • MADE SIGNIFICANT PROGRESS IN II MONTHS • NUMEROUS nOCEU PARAMETERS HAVE • RECEIVED OUTSTANDING SUPPORT, ENCOURAGEMENT AND SEcMMVESfUAKD HELP FROM THE ICF UBS • HAVE FULL RANGE OF CAPABILITIES AVAILABLE • UNOCOOOOUAUIYSHEUSHtHEI-JnE HAVE IEEH PRODUCEDM • 21 PAPERS AT THIS UEETWa • SEE PAPERSIV 0. SCHROEHCAAEY ANO • HOW CAN WE HELP YOU? 10UTTEMCHNEM ^O.nutAniHKf SJSt NOVEL POLYMER DEVELOPMENT • AlUTENALIHATHOPAQUtTOUVSUT TRANSPARENVOH CAYOQEMT TOC VBAUUCH TARGETST IS NEEDED • MLtVamJUmMACtNEAPKMSWOl SUITED. WAS mnHESSEO ANO JESTED ll M O.JK— AbMr^IlCnMrtuMi • SHEUS AND COATMOSWERE MAX i • SEE PAPER IT I. UcQUUAH t PRODUCTION Or RANDOMLY ROUQH INTERFACE. ROUGH PLASTIC DISC FITTED TO END OP MICRO MACHINED CYLINDER Thri Measurement of Randomly Rough Surface^ V jnlaaecDaffitia. Yv flPTlfoffi111 Scanning Microscopy U.v. LIGHT POLYMERISATION C.J.Hotmftel4 d T.J.Coldaack IMERSON A SERIES OP BATHS DESIGNED TO DISOLVE THE PLASTIC DISC AND TO EXCHANQE TOE SOLVENT. WW |>W\\>vV 2nd CYLINDER FITTED ON AND FOAM AWV FILLED. POLYMERISED AND SOLVENT •JWV EXCHANGED IN PREPERATION FOR CRITICAL POINT DRYING. C31 = 3 Fl#uc 3 Figure 1. CONFOCAL LASER SCANNING MICROSCOPE RICHTMYER- MESHKOV MIX EXPERIMENT PROPOSED TARGET DESIGN U- p [] CRYST1C RESIN CYLINDERS 50 mg/cc CI LOADED FOAM • 200 mg/cc S LOADED FOAM H PARALYNE 'C' ABLATOR % RANDOMLY ROUGH INTERFACE LttM OBJECTIVE I ABLE L ENS sx uk as sax looac •HA. 0.15 0.30 080 Oils ago RES 2.5 1.3 0.76 0.45 OA2 (urn) FOCUS 100X LENS 2QX ZOOM 20X I ENS 1Q0X ZOOM DOTH .7.0 Id 0.63 022. 030 (um| I.BSum rms 3.74um rma MAX. FIELD 3400 1300 000 310 130 OP VIEW X X X X X (urn) 1430 710 3S3 143 71 20K ZOOM SEI0- ANBUE 9 IB 30 58 64 OF INCIDENT CONC) E COMPARISON OF I00X OBJECTIVE AND 20X OBJECTIVE INTENSITr MAPS Figura 7 r.»ph nt in (rmti Boimhnftn v 7nnm Magnification EFFECT OF SHAPE OF OPTICAL PROBE ON A SLOPING SURFACE 3X Ob(*cthrt LOW NUMERICAL APERTURE LENS 20X Objactlv* SOX Ob|«etlva IQOX Ob|«eil»» Zoom Magnification FlUW - - - - - I >|UII ID Comparing the "jigsaw" image with a 20x obj 55x zoom image Comparison of line-outs from Fig. 9 shows a good shows the improvement in image quality obtained by using "ji( correlation between the two sets of data, indicating saw" images rather than low-magnification objectives. the high fidelity of the "jigsaw" technique rms s 5.53nm Image 2 (jigsaw): 50x obj, 49x zoom ims = 4.17(im Comparing the "jigsaw" image with a 50x obj 20x zoom image shows that small contiguous areas can be successfully "jigsawed" together to reproduce a larger area. rms = 4.07pm brags 2 (jigsaw): 50x obj, 49x zoom rms = 4.17pm Height (jim) os>i < 5T s ® ® 2 w 3 IISOD') —* —. 3O U) <&£ =-»s =O 3 Q. _ a®if O5, 2 ~ = §2.0 ^ MM 0) JS ro 2 w(Q 3 • w » n o® Z. 3* 5 « S? a (D CnidiskiiL We have shown that the laser acanttng Microscope can be used to adequately characterise rough surfaces of the order of 6 surface roughness, provided that I. The 1 are twd to usage the steep microfcetures In such surfaces. 2. Areas larger than that normally Imaged -with the high MA. can soil be. measured using the 'Jlgurw1 technique described above. 3. The use of the high N.A. lenses in coojuncttto with the 'Jigsaw technique provides better data than the lower NJt. larger field of view lenses. However. many challenges still malt us la the characterisation and production of polymer foama for a Rtehtmyer- Meahkov mix experiment. PRODUCTION AND MEASUREMENT OF RANDOMLY ROUGH SARAN FIT,MS FOR ABLATION FRONT INSTABILITY EXPERIMENT Anthony C Tyrrell Radiation Physics Division Atomic Weapons Establishment Aldermaston, Reading, Berkshire UK 1. INTRODUCTION Experiments were planned using random rough surface to investigate the Rayleigh- Taylor instability at the ablation front, where the Attwood number at the interface can be large. These experiments were also designed to eliminate edge effects which could be the reason for foil break up observed in previous ablation front experiments. 2. EXPERIMENTAL These requirements to produce measured random roughness in a Saran film to make smooth discs to fit in the end of the driver cylinder required the developments of our target fabrication techniques (Figure 1). i Saran which is a 80:20 mix of polyvinylidene chloride and acrylonitrile which a density of 1.61 g/cc and 57.5% chlorine content, is normally produced as a smooth film by coating a microscope slide with a Saran solution. The thickness is controlled by the solution strength and the withdrawal rate of the slide. To produce the random rough surface a number of slides were made with different ground surfaces on one side. These rough surfaces were initially measured on a Talysurf to establish the optimum roughness for the experimental requirement (Figure 2) Commercial PVDC film was considered but the rolling marks were too wide for the 200 n diameter discs also the analysis of the film was uncertain. (Thought to be 90% PVDC 10% PVC). Also ICI Viclan a 90% PVDC 10% methylacrylate was considered as the CI content was 65% and the density 1.73 g/cc but the oxygen content of 3.6% w/w made the Aldritch Saran 220 containing 5.4% nitrogen but no oxygen a better choice for the experiments. When Saran films were produced on these ground slides the top surface of the film was measured on the Zygo Maxim 3D and was found to be* smoother than the glass surface (Figure 3). The Zygo Maxim is a dynamic phase shifting interferometer which requires a continuous interference pattern over the examined area to give a satisfactory measurement. The ground surface was however too rough to enable measurements to be made on the Zygo. This gave the problem of how was the rough surface to be measured? Attempts, using instruments available in the UK, showed the Zeiss Laser Scanning Microscope with surface topography software gave data on both the rough glass surface and the Saran film when a sample was peeled back. The Saran was shown to have made a good replica of the glass surface (Figure 4). The Zeiss LSM is a confocal microscope with a He/Ne laser source and this is fully described by Colin Horsfield (Reference 1). Measurements made after further experience with the LSM gave data for the rough side- in better agreement with the Talysurf measurements (Figure 5). The Saran on the smooth side of the microscope slide was measured on the Zygo to give comparative data for these experiments (Figure 6). To produce the 200 fi diameter discs required the normal punching techniques had proved unsatisfactory. Rough edges were formed making a poor fit in the hole in the gold cylinder produced from a diamond turned mandrel. This was the probable cause of the edge effects observed previously, therefore an improved disc had to be produced. A local firm, Exitech Ltd, were approached and eximer laser ablated discs were made using both direct contact masking and projection masking. Both of these methods produced good quality on 200 fj discs. As repeatable exact 200 )j diameter discs were difficult to produce using laser ablation the discs were accurately measured and the holes in the cylinders made to fit (Figure 7). When the discs were fitted into the cylinders, measurements were taken on the smooth samples of Saran on both sides and the smoother side of the rough samples using the Xygo. All this data obtained on the Zygo maxim has been stored for further analysis including Fourier analysis. The rough surface data measured on the Zeiss LSM, were also stored to enable Fourier analysis to be compiled (Reference 1). 3. CONCLUSION The improved disc shape has given satisfactory results from these targets on both the smooth and rough Saran samples (Figure 8). i REFERENCE 1. C J Horsfield, T J Goldsack. The Measurement of Randomly Rough Surfaces in Laser Targets by Confocal Laser Scanning Microscopy. FIG. 1 TIG. 2 Rf^nlrfmwntw TALYSURF I 1. To produce a quantified random rough surface' GLASS SURFACE-'60' RMS-0.543U on a Saran film. 2. To produce discs from theSanm fllma with smooth edges.. SARAN DISCS •i.m * > I l« Itlln • l.m - SMD™/^ Vs\^naJGH TALYSURF GLASS SURFACE'125' RMS 0.655u DRIVE DRIVE :.im a i •i.m < h* l< iilin • • • 'i.li""i:. I FIG. 4 FIG. a ABLATTON FRONT INSTABILITY EXPERIMENT ROUGH FOIL CHARACTERISATION v : rj ' w - - • - '- 'SMOOTH" SIDE OF SARAN 'SCF ;.v>r - GLASS SURFACE RMS 1.O0U PV 638.ee na rn 93.60 na R« 73.35 n. L 1 L " -* S , ,v - • ~ r . . •V • •ft,-.. '••Ti ^ • i- : l»> SARAN SURFACE RMS 1.07U ABLATION FRONT INSTABILITY EXPERIMENT ABLATION FRONT INSTABILITY EXPERIMENT ROUGH FOIL CHARACTERISATION SMOOTH FOIL CHARACTERISATION 'v. ^ AV • • ANALYSIS OF WHOLE DISC SHOWS SLIOHT OISHMQ Mum carter* 10 M«* WHKM DOIMNATCS RMS ROUOMNCBB VALUE UMESCAN ON A FLAT REGION SHOWS THE TRUE SURFACE ROUOHNESS FIG. 7 SARAN DISCS FIG. 8 *-m. . ' «• ' . ' "J PUNCHED 6SOUDIA. X200 ABLATED 200u DIA. X400 til W-'-.X..1" "J !«S3'''' : » ^ "-li PUNCHED 650u DIA. X400 .ABLATED 200u DIA. X200 Modification of Carbon Fiber Geometry Using an Oxygen-Plasma Etcher, Daniel S. Brennan, Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, NY 14623-1299 Requirements of a new mounting scheme for OMEGA upgrade targets were developed during 1992. Beam clearance issues made the previously used "horse shoe" mounts unacceptable. During investigations of candidate materials for a stalk or tripod mounting scheme, carbon fibers emerged as an attractive possibility. Desirable characteristics of these fibers include stiffness, strength, and low atomic number. Unfortunately, the thinnest commercially available fibers are over 5 Jim in diameter. A mount constructed of these fibers would place too much mass near the target. Initial attempts were made to thin the carbon fibers by exposure to an oxygen plasma. It was discovered that the fibers could be tapered by arranging them vertically between the parallel electrodes of the etcher. Subsequent investigations seem to indicate that directional non-uniformities in the plasma are responsible for this effect. Further study has focused on selecting a suitable precursor fiber and on tailoring the taper by position adjustment and shielding. A reproducible method was developed for smoothly tapering fibers from a base diameter of 8 to 11 p.m to a tip diameter of approximately 1 iim. Current work indicates a dependence of etching characteristics on internal microstructure of the fibers, this aspect is being investigated further. 1 Introduction] I Fiber Selection Tapered carbon fibers provide a viable method for A suitable fiber type must be selected from a wide mounting larger-size fusion targets yarieiy of commercially available fibers ;: yajfe um -JtL LUW LLkW • Tapered carbon fibers are a good material for target mounts • To provide a workable mounting system, fibers must be free from because of the following characteristics: bends and twists on a macroscopic and microscopic scale. These • tow mass features are present In some fibers as an artifact of the • low atomic number manufacturing process. • high strength - high modulus • A balance must be achelved between high modulus and high strength. High modulus Is desirable to provide a stiff target mount • Production of suitable tapered carbon fibers with a high resonant frequency. High strength Is desirable to Involves two main steps: prevent breakage during fiber handling and mount assembly. • choosing an appropriate initial fiber - tapering of fiber by oxygen plasma etphlng T11M Commercially available carbon fibers take many forms a* The need for high modulus and high strength must be balanced to provide workability « 4 CL a ca a - 2 4) L&MI; S 1 J- f •• • ?; . , - J ; V {« t 200 400 600 800 1000 Tensile modulus (GPa) nut [Fiber Etching] Carbon fibers are exposed to an oxygen plasma Carbon fibers are tapered by exposure to a radio-frequency-generated oxygen piasma • ua j*. . . aa* • Oxygon plasmas are commonly used to remove organic materials such as photoresist fn semiconductor device processing. Carbon Is removed primarily through the following reaction: C + 0*—»C0 + C02 • In our case the fibers are arranged in the etcher vertically, perpendicular to the two parallel plate electrodes. It Is believed that directional nonunlformltles In the plasma are responsible for the tapering effect (Summary ( Tapered carbon fibers provide a viable method for mounting larger-size fusion targets • Tapered carbon libers can be used to create a target mount with the following features: - high strength • high stability • low mass near target - constructed entirely ot taw-atomtc-number materials • Future research will focus on the following areas: - tailoring fiber geometry to suit our needs • developing ol tools and fixtures to facilitate liber handling and mount construction tun rim Poster 2 Session I THE ETCHING OF CARBON FIBERS AND THEIR USE IN PRODUCING POINT BACKLIGHTERS. Joyce E. Moore. Norman E Elliott, Harry Bush. Jr.. Peter L. Gobby, Veronica M. Gomez. Vivian A. Gurule, and Bobbie F. Henneke, Los Alamos National Laboratory, P.O. Box 1663 MS E549. Los Alamos. NM. 87545 Small carbon fibers have been etched to 5um or less using plasma ashing techniques. These fibers can then be coated with virtually any material to produce point backlighters. Specifically Bi, Ti and Ag have been used to fabricate backlighters for laser targets using this technique. LA-CP-93-134 Poster 3 Session I Free-Standing Foil Fabrication THOMAS E. ALBERTS (510) 447-0555 W.J. Schafer Associates IAvermozCj California, 94550 and JAMES L. KAAE (619) 455-2957 General Atomics Son Diego, California 92138-5608 A variety of filters and foil targets are necessary components to diagnostic instrumentation used at Sandia National Laboratories in Albuquerque, New Mexico. The GA/WJSA team has been tasked to support the foil target and filter needs of the PBFAII, SABRE, and Two-Stage facilities at Sandia. We have developed or tested a variety of processes to fabricate and mount thin flat free-standing foils of various materials for use as targets and filters. - To date the materials we have -worked -with are Ag, Al, Au_ Cu, In, Parylene-N, Parylene-D, Si, Sn, and Ti. These foils range in thickness from 1100 to 50,000 A. The size of these foils range from 3 mm diameter to 35 mm square. Much of the effort of development is directed toward fabricating thin foils that are intact, -wrinkle-free, and mounted on a transport frame. We have used a number of methods to fabricate these free-standing foils. Gener- ally the foil material is first deposited onto a temporary substrate using evaporation, sputtering, or chemical vapor deposition. In one technique the temporary substrate is a durable material such as glass which is coated with a water-soluble release agent such as polyvinyl alcohol or a detergent. In another technique the temporary substrate is a solvent-soluble sheet such as cellulose acetate. Second, the foil is transferred from its substrate to a transport frame. Different transfer techniques are appropriate for each temporary substrate type. We have met with at least partial success for all materials at thicknesses requested and outstanding success with some of the materials. This is a report of work sponsored by the U.S. Department of Energy under Contract No. DE-AC03-91SF18601. LA-UR Los Alamos National Laboratory it operated by tha Univanlty of CtlllorntM tor tha Untied Stiles Department of Energy under contract W-740S-ENG-3C. TITLE: POLYMER FILM THICKNESS MEASUREMENT BY FTIR AUTHOR(S): Wayne L. Bongianni, MST-7 SUBMITTED TO: Ninth Target Specialist Meeting to be held at the Naval Post-Graduate School in Monterey, CA the week of 7/5/93 By acceptance ot this article, the publisher rec*gnlies that the U.S. Government retains a none«clusiva. royalty-free license to publish or reproduce the published form ot this contribution, or to allow others to do so. for U.S. Government purposes. The Los Alamos National Laboratory requests that the publisher identify this article ss work periormed under the auspices ol the U.S. Department ol Energy. Polymer Film Thickness Measurement by FTIR W. L. Bongianni, Los Alamos National Laboratory The technique of fast Fourier transforms in the infrared, FT-IR, has been used to measure thin polymer films. An FT-IR displays the frequency dependence of the film's absorption, (or its reciprocal, transmittance) independent of the source spectrum. The absorption, A, at any wavenumber is given by (1) where X is the intensity of the transmitted light with the sample in place, and Io is the intensity without the sample. Within the film, the fraction of light intensity absorbed per unit length is constant, giving rise to the exponential expression (2) where a is the absorption coefficient and x is the path length of the light. Solving for the thickness, by combining eqs. (1) and (2) and re normalizing yields A = ax (3) Equation (3) ignores the effect of multiple scattering by the surfaces of the film, which is slowly varying when the film thickness is small; that is, less than a micron. However, multiple scattering of a thick polymer film can be used to calibrate the absorption constant of the given polymer. This self calibration is based on the interference fringes produced when the film thickness is an integral number of half wave- lengths. On a wavenumber display, a film with no dispersion displays a sinusoidal transmission with adjacent minima and maxima of equal spacing. The inverse of this separation is half the optical thickness of the film. The index of refraction of the film is obtained from the transmittance of the minima and maxima. In the case of a well known polymer, such the xylylene polymers, the index can be obtained from a reference1. The transmittance spectrum of a thick Parylene D film as taken with a Nicolet #710 FT-IR is shown in figure l. Mote the sinusoidal "base line" from 2000 cm""1 to 4800 cm"1. As many as 9 minima and maxima can be counted and used to obtain the half wavelenth. Once the thickness is determined a single, large, well resolved absorption line is measured in absorbance units. In this case, the 1077 cm"1 line in the "fingerprint" region at Figure 1. FT-IR Transmission Spectrum of Parylene D Thick Film. Figure 2 / * / • 7 t t f 4 /< S/ / L.4? / • 9' r / / / 0.1 1 10 100 TlrielmeM. ° PaiylrocNdata Theory w constant Theory w/o constant Parylene 'N' Absorbance of 820 cm-1 Line as a Function of film Thickness in Microns. The solid line represents the linear exprssion for absorbance = 0.146 * thickness + 0.039 with a correlation to the data points of 99.9%. Figure 3. AIM of Thin Parylene N Film. ' xt tr.i , ••iX • O . ' ffi CO. \ ! t—1 • • t/t .'•.t o : . Ill r 'JJ u II iti CO cHO'i O .IVI IJ rrj nj nil , o LL . >2S ** WvM XfMC i t f* 4l U < r w jy » < ». * i ^•'jf ' > ' W ?mf / ' '^"vR * ( « if ^ t*' I h mh (V ^ «H , % ^ J' SWf'SS » 9> ,>- rtfp ft I. MM W , w 1 if : & m Wfmmm 4- O J- li L ABSTRACT Event: Popt^T Session, of the Ninth Target Fabrication Specialists' Meeting General Topic: Polymeric Thin Films Title: Techniques for Producing Free-Standing Thin Films on Frames The procedures of vapor-deposition polymerization, spin coating and orientation-dependent etching have been employed to make free-standing thin films of Parylene-N, parylene-D, polystyrene, polycarbonate and perfluoro-dimethyl- dioxole/tetrafluoroethylene copolymer (Teflon® AF-1600) . The polymeric materials were vapor-deposited or spin-coated onto substrates of polished single-crystal silicon (wafers) and removed on frames of various shapes and sizes after application of adhesive and an etching process using potassium hydroxide. Thicknesses range from 2000A. to 1200OA. authors: J.H. Aubert Sandia National Laboratories organization 1815, mail stop 1815 P.O. Box 5800 Albuquerque, New Mexico 87185 telephone: 505-844-4481 or 505-845-7 844 facsimile: 505-844-9624 William Fr&re McNamara organization 1815, mail stop 1275 Sandia National Laboratories P.O. Box 5800 Albuquerque, New Mexico 87185 telephone: 505-845-7306 or -7611 or -7902 facsimile: 505-845-7 890 or -7 650 s YHO p s i s Spin coating provides a convenient way to produce thin films of various polymeric materials on a variety of substrates. Experimenters in target physics have a need for free-standing polymeric thin films within frames that may range in thickness from 1000 Angstroms up to two microns. The films typically must be pinhole-free and as uniform as possible. Glass as a substrate material is problematic in that slides are generally not clean, even directly from the box in which they are shipped. Another possibility for a substrate material is highly polished single-crystal silicon, available and widely used in the form of wafers by the microelectronics industry. Wafers called "monitor" wafers, used for judging the quality of a process or for checking a piece of equipment, are suitable for fabrication of pinhole-free thin polymeric films either by spin coating or vapor deposition and subsequent removal by means of liftoff in water. They are relatively inexpensive and remain clean if one is careful not to allow dust to enter the box in which they are shipped, and if the time the box is left opened is kept at a minimum. In addition, the wafers are physically separated from each other in the box, allowing easy manipulation with tweezers. Wrinkle-free and uniform free-standing polymeric films are desired by experimenters. The uniformity of a film on a silicon wafer can usually be seen by the naked eye, since the highly polished surface is similar to that of a mirror. An excellent method for measuring the uniformity and thickness of films on silicon wafers before mounting on frames is ellipsometry. Multiple points can be non-destructively measured on the wafer surface, providing a thickness map of the film on the substrate. Use of water as a medium to lift films off substrates and subsequently affix them to frames with adhesive is a common technique. However, it is somewhat difficult to fabricate wrinkle-free films within frames by this method. If the frames in question are adhered to the film that has been uniformly spin-coated or vapor-deposited onto the silicon wafer, orientation-dependent etching can be employed to slowly and mildly etch the silicon and silicon dioxide (on the surface of every silicon wafer) from underneath the polymeric film, allowing release of the frame with a free- standing film adhered to it. If the bond line between the frame and the film is secure, the film, now free-standing within the frame, should have close to the same mechanical characteristics as it had while on the wafer surface; in general, taut and wrinkle-free. Orientation-dependent etching relies on potassium or sodium hydroxide dissolved in water at various concentrations and temperatures to etch silicon of a known crystalline orientation in a preferable direction. For the materials made in this study, the crystalline orientation of the silicon wafers was ignored, since the amount required to be removed for release of a frame with a film was so small. The polymeric materials used for this study included Parylene-N and -D (vapor-deposited onto the wafers in a Parylene coating system), polystyrene (dissolved and spin- coated in toluene), polycarbonate (dissolved and spin-coated in bromoform) and perfluoro-dimethyl-dioxole/ tetrafluoroethylene copolymer (Teflon® AF-1600, dissolved and spin-coated in Fluorinert FC-43). The frames were adhered to the films on the wafers with PRS-1201-Q polysulfide sealant (a two-component sealant containing polysulfides and lead oxide made by semco) . After curing of the sealant in a humid oven overnight at 60°C, the film was cut away from the outside of each frame around the entire perimeter with a blade to allow entry of etchant. The entire wafer was then immersed into the etchant (KOH dissolved in water, 0.25N) and left until release of the frames was achieved. The frames with their free-standing films were then rinsed in distilled water and allowed to dry and suitably stored in a dry environment. An alternative approach would be to first coat the silicon wafers with some type of photoresist as a release layer (preferably colorless), overcoat the photoresist with the polymeric thin film, affix the frames to the film and etch the photoresist release layer from under the film with ammonium hydroxide after cutting the film at the perimeter of the frames. The technique outlined above can provide an easy route to high-quality free-standing polymeric thin films within frames without the rigors of using water with its high surface tension as a medium for a wrinkle-free film. In addition, spin coating or vapor-deposition polymerization onto silicon wafers allows relatively easy and inexpensive production of uniform, pinhole-free films. Fabrication of Thin Planar Discs for use in Long-Scale-Length-Plasma Experiments, Stephen G. Noyes, Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, NY 14623-1299. Very thin planar discs are fabricated from polymers and metals. Using this technique, planar discs may be produced in a variety of diameters and thicknesses. Use of a plasma discharge enhances adhesion of metals and polymers in multi-layer discs. Types of polymers and metals as well as equipment and production procedures will be discussed. The process of making disc targets for use in long-scale-length-plasma experiments involves the use of specialized materials, equipment and assembly techniques. Parylene was selected as the polymer of choice for making discs because it may be accurately and uniformly deposited in thicknesses as thin as 0.1 itm. Parylene also releases from the substrate with slight mechanical assistance when small amounts of water vapor are applied. The process of cutting the disc is accomplished by the use of a motorized turntable and cutting arm assembly similar to components of an ordinary phonograph. The turntable is constructed so that the parylene-coated coverslip is held down by the use of vacuum. Positioning of the cutting edge at a desired radius from the turntable's axis of rotation is accomplished with the use of a 1" x,y,z positioner. The cutting arm is hinged on 2 ball bearings which allow for very little lateral movement while having only slight friction to movement in the vertical plane. Raising and lowering the cutting arm is done via a cam-type action. The cutting is accomplished with a #11 Bard Parker surgical scalpel blade set at 45 degrees to the horizontal plane of the rotating turntable. In practice, the parylene-coated cover slip is placed at or near the center of the turntable and a cut is made at a radius of about 3 mm. Individual discs are then cut from material just inside this circle; working inward until the circle is completely used. Water vapor is then deposited on the cover slip by means of blowing through a plastic tube while simultaneously lifting the edge of the waste material. At this point, all that remains on the substrate is the individual discs. In order to remove the discs, water vapor is once again condensed an them while a finely-drawn glass capillary probe is used to lift the disc form the cover slip. After a few seconds, the disc should be dry enough to set aside. In general, discs 500-600 Jim in diameter and 6 in thickness are very stable and do not pose any problems in handling. When the thickness of the disc approaches 1 |im, however, it is important to remove it from the cover slip and mount it immediately using low-intensity UV light with the UV curing epoxy. This process greatly reduced subsequent distortion associated with removing all of the discs before beginning ihe mounting process. Discs fabricated from alternate layers of parylene and aluminum require plasma cleaning of the aluminum layer before parylene is deposited in order to avoid delamination of the metal and polymer layers. Plasma power is set at 1 Watt for about 5 min. to accomplish this. In summary, disc targets for long-scale-length-plasma experiments have been produced with diameters of 300-600 |im with thicknesses ranging from 1 to 6 Jim. Both single and multi-layer materials are able to be fabricated with equal ease. Planar targets are used to evaluate plasma conditions that will exist on the OMEGA Upgrade S&T «S&T Fabrication of Thin Planar Discs for Use in Long-Scale-Length Plasma Experiments STEPHEN G. NOYES University of Rochester Interaction 500 A AJ beam barrier layer Laboratory for Laser Energetics UH A LLE^I 600 jimI Experiments at LLE utilize threelarget types : . S* Circular microscope cover slips-are coated with parylene to form a desired substrate thickness Witness plate 0- Cover slips' To vacuum Parylene ' monomer system Disc preparation is accomplished Fabrication is accomplished through using specialized equipment a sequence of operations inUHf* Razor blade Rotating disc Cut is made around discs; excess materia] is removed leaving only the discs. mil Disc handling is accomplished using both freehand- Completed discs are mounted on parylene-coated and manipulator-assisted techniques spider webs using UV curing glue Freehand Manipulator m UV penllght Hand held drawn glass capillary Water vapor Is blown through tube and deDOSlted on dlcsc to TIIM PLASTIC DISC FABRICATION FOR AWE EXPERIMENT. Leandcr J. Salzer, Los Alamos National Laboratory, P.O. Box 1663 MS E549, Los Alamos, NM 87545. Small disks of polyphenylene sulfide (PPS) and Delrin have been required for experiments conducted at the HELEN laser facility at AWE. A mold was constructed which allowed the fabrication of the PPS parts to size. The Delrin parts were machined from bulk material using a novel approach developed for this experiment. Data on the surface finish and flatness of these parts are presented along with the fabrication steps. LA-CP-93-117 FORMING ELECTRODES FOR EDM SMALL HOLE DRILLING. Leander J. Salzer and Gerald Rivera, Los Alamos National Laboratory, P.O. Box 1663 MS E549, Los Alamos, NM 87545. Small diagnostic pinholes, some as small as 5urn diameter are required for experiments conducted on NOVA. A wire electode dressing attachment was constructed and attached to a Panasonic MG-EDOl Electro-Discbarge Machine for the purpose of electrode forming. Data on hole size, methods and materials used in electrode forming will be presented on this poster. LA-UR-93-133 Sputtered Polymer Films for ICF Target Applications E.Ii.Fiarea, E.J.Hfllsh Lawrence Ziivermore National Laboratory University of California, Liverinore, CA 94 550 ABSTRACT We have been Investigating the feasibility of depositing polymer materials by the sputtering technique onto ICF Targets. Sputtering polymer materials has the advantage of depositing very thin films, (I.e.. 1500A to 5000A range). Furthermore, sputtering lends Itself to co-sputterlng with a metal which also has interest in target applications. Our studies have been concentrated on Teflon, (a polymer containing fluorine), and TPX, a pure CH polymer. This sputtering process is unique for applying a thin polymer film In a short period of time. Recently we reported the sputtering of several polymer films for obtaining a usable CH polymer coating. These included Acrylic, Polyproplyene, Polystyrene, Parylene-N and Teflon, (PTFE). Of these polymers, Teflon is the most feasible since Its melting point Is high and it sputters well. Recently we have been doing experiments consisting of sputtering with TPX, (Poly-4- Methyl-Pentene). TPX Is the most desirable polymer since It Is a comparable to the polymer used for fabricating micro-spheres. Applications- One of the applications is to create a controlled perturbation In the form of a narrow strip to be deposited onto a CH micro-sphere. This experiment is an outgrowth of present Instability studies on a plane geometry. Our recent progress has been the development of a technique for sputtering a controlled defect onto a spherical surface. This technique utilizes a collimated mask and a rotating sphere in order to deposit a uniform band around the circumference of the sphere. Results to date Indicate a profiled coating of about 110 Microns in width and 2500A in thickness with the profile having a uniform shape around the circumference of the sphere. The second application is a free standing 1400A thick fluorine containing polymer that Is used for x-ray absorption measurements. The film Is to be tamped on both sides with 1000A of CH film. Because of the thickness specifications, sputtering Teflon Is the best solution for this application. Results- The coating rate is an Important parameter In depositing these coatings since the thickness must be sputtered In a time frame without deforming the substrate. Surface smoothness as well as measurements of the bulk density and composition of the sputtered PTFE and TPX Is an Important parameter to the NOVA experiments. The polymeric materials will also be analyzed by IR Spectroscopic absorption measurements that give Information on the structure, cross linkage and impurities. We will present our data on the density, composition, surface smoothness, IR Spectroscopic absorption measurements as well as the technique used to deposit a narrow strip onto a NOVA target. Acknowiedaments- I would like to thank ihc following professionals for their efforts and contributions which made this poster session feasible. T.P.Bemat. RJ.Wallace, C£-Moorc, E.F.Lindsey, & G.E.Ovenurf, * R.eferences- 1. The 39th. National AVS Symposium. Chicago. Illinois. November 9-13,1992 Surface Roughness n j croscope '•'< Hi I II 5>0_fll-ri Scan size • \;> 10,0 pm • Setpomt -.-J >.. -5.6 O Scan rate . .2.0 Hz . . Hunker of sanples 512 j . . v'i /".« r J • I '.. d, _lna9e_Stat.i.stjcs- Z ranye iRp) 71.711 HH Mean 0.O0G nn Rms CRq) 7.512 n* Mean rousihriess 5.833/ru* Max heightt fRnaK.lRnaK.l1 74.170 HH ' Surface area • Surface area diff X Z.OOO Un/diu Z 100.000 nn/.diu Teflon Sample zB7 . PolyfTetrafluorethylene.) Section Analysis Marker Spectruw .Zooh ' Center Line ' Clear Horiz di stance Uert distance Angle Spectral any Teflon SaMple «87 PolyCl DC Center line Off Surface Roughness Microscope • HSlll Sfi_flFM Scan size 10.0 mm Setpoint -5.6 U Scan rate 2.0 Hz Himber of sanples ' 512 2 ran 2.000 uM/diu 100.000 nn/diu TPX Sample ..9 Pply(4-Methyl-P^.ntene) Section Analysis Line Marker Spectrun 2OOH Center Line Clear Section Analysis ' « .5 10.U." S p e c t r ! Horiz distance Uert distance Angle Spectral axp 0.874 iW TPX Sample t>3 Polyt4-Me DC Fixed 1 ine 2oox 8: 1 Sputtering Characteristics of TPX Sputtering Characteristics of Teflon A. SPUTTERING RATE A. SPUTTERING RATE Soulltllno Characlallellc ol T( PoirC-Melhrl-Penlene) TEFLON i* tee ice PII U. COMMENTS H. COMMENTS 1. STAIILE OPERATION WITH LOIV EKOSION KATE" 1. STAIIl.K Ol'KKATION WITH IIICIl I'.HUSION HATE 2. A VIAULE SrUntHINC MATERIAL 2. A VIAIILI: SI'TRRIKKINO MATEKIAL 3. A I'UIIE cil I'OLYMEK C. I'OLYMEU STRUCTURE FORMULA C. I'OLYMKR STRUCTURE FORMULA Trflnn / > I'olfCl'clralluurucllijIrnt) •ICI-' -CK )• ft TI'X \ -I J/.< I'UI>(-I-IMCIIIJ I- t'ciilcnc/ CIL-.C'l CII, . 1'. - v £ g Density & Composition ^ ft Infrared Spectra of Sputtered Polymers B Teflon Teflon TPX •y ft Density (gm/cm3) Density (gm/cm3) Sulk ipuctirad Balk Sputc<(«4 a.it l.u O.tt O.tl V TPX Composition (at%) Composi(ion(al%) Known IPtttt»«d Mova Spact«r«4 Cr>I ««.!11.«7) 11.1H.1" C•I 11.1««.(1 » 71.010.07 1 I 1M> »M 1M jtaea •*"* l!** mm 1 V* & V Preliminary results depositing perturbations on micro-sphere ^ I Schematic for depositing narrow strip on micro-sphere fg A ' < I • . -Collimated mask vt. ••-•:•- &X- s oWlJ, • 'fa '<. .JZL_- IfcllWn t .(Mi3l ESCA analysis of Ti Schematic for collimated mask technique & w gg co-sputtered with TPX .18=- V$ 1 25 (i x 75 p Slit 1 I; • H \ 50pSpacer \\ I \ •jS 25 (J x 75 p Slit / ii a V f - ^CN Used lor high definition sputter coating <0 « I .1 % iivouc rxriT. yj! P •'IA CONSIDERATIONS IN THE ANALYSIS OF X-RAY FLUORESCENCE DATA OF AU:GD FOILS R. E. Turner, C.E. Moore, R.J. Wallace, E.L. Pierce LLNL We recently produced a film of gold and gadolinium by simultaneously sputtering the two metals onto a glass substrate. To measure the mass fraction of each of the elements, the sample was subjected to x-ray fluorescence analysis. The foil was thick enough that appreciable absorption of both the exciting and emitted radiation takes place, complicating the analysis. In general, the intensity (number of photons per second) of an emitted x-ray line from an element irradiated by this instrument can be written Kline) - Jdx / d(hu) p(hu) p I(ht))inc Y(line) * exp(-( Zp(hu) p) x) * exp(-( E p(line) p) x) where \l is the mass absorption coefficient for an element, which depends on the element and the x-ray energy; p is the density of the emitting element = f*p(average), where f is the mass fraction, p( average) is the average density; the summations are performed over all elements present, and their absorption coefficients; I(hu)inc is the incident radiation onto the sample foil, as a function of photon energy; Y(line) is the probability that the absorption of a photon will result in a detected photon at the given line energy (fluorescence yield and detector efficiency); the first exponential is the absorption of the incident radiation as it enters and goes through the film; the second exponential is the absorption of the line radiation as it goes through and exits the film; x is the depth along the incident or emitted photon path (for this machine, both paths run at a 45 degree angle to the normal). The integral over x can be done analytically, leaving an integral over frequency space. This latter integral we approximate by a sum over seven groups or bins of photons, spanning 8 to 10 keV, 10 to 12 keV, 12 to 14 keV, 14 to 16 keV, 16 to 17.5 keV, 17.5 to 18.5 keV, and 18.5 to 20 lceV. These groups adequately represent our incident spectrum, which is due to a thick target (Mo) bremsstrahlung source, filtered by 50 |im of Mo, run at 40 keV. The number of incident photons within each group is calculated from standard published data, attenuated by the Mo filter. Note that only the relative shape of the spectrum is important, as the overall absolute intensity can be factored into the constant Y. The first two groups contribute only to the Gd line at 6.06 keV, since the absorption coefficients for the other elements are very small in this range. The last two groups contain the large contribution from the Mo Ka and Kp line radiation. The integral for the emitted line intensity has three unknowns: the fluorescence efficiency/detector efficiency, Y; the mass fraction of gold, f; and the product of the average density and the foil thickness. We do the indicated integral numerically on an Excel (C) spreadsheet, using these groups, for three lines: the Au La line at 9.7 keV, the Gd La line at 6.06 keV, and the As Ka line at 10.5 keV. The arsenic is present in the glass substrate. We have samples of pure Au and pure Gd, with the thicknesses measured both with a stylus profUometer, and by the As line attenuation. We also have bare glass. From these samples the constant Y is obtained for the three elements, except for an assumption for the As which is discussed later. We then measure the Au La, the Gd La, and the As Kalines from the sample. The results are compared with the spread sheet calculations, and the variables f (mass fraction of gold) and pt (average density times thickness) are iterated until a satisfactory match is obtained. The calculation is actually over-determined, since 2 measurements are sufficient to solve for the 2 unknowns. This provides a useful check. In practice, for our foil thicknesses, the attenuation of the As line is very sensitive to p t, while the ratio of the Au to Gd L lines is most sensitive to f. This makes for a rapid convergence, so that doing the iteration on the spreadsheet by hand is reasonably fast. A comment on the calculation of Y for As, from the bare glass data. A proper calculation requires that we know the glass composition. The composition does not "cancel out" in the calculation, since the absorption coefficients depend on the photon energy, and the shape of the spectrum incident on the glass is modified by the presence of the Au and the Gd. We have modeled the glass composition over a wide range of As levels, Si, Na, K, etc. Fortunately, the results are very insensitive to the assumptions, and no appreciable error results from simply modeling the glass as a thin slab of arsenic. Likewise, absorptions involving atomic transitions in shells higher than those of interest (e.g., M shell absorptions in Au) should be disregarded since they have zero probability of leading to a lower shell (e.g., L line for Au) emission. Since the absorption coefficients are dominated by photoelectric absorption, and we do the integral over only the energies near the appropriate transitions and higher, this is essentially built into the calculations. In the measurements we have presented, all 3 data points agree well with the calculations, giving us confidence that the approximations. are reasonable, and that we have a good measure of the ratio of the two elements. Dai ry ncgu i i iai, A POLYMER COATING, WHICH IS AN ABSORBER IN THE UV, AND TRANSPARENT IN THE VISIBLE, IS NEEDED FOR FUTURE CRYOGENIC TARGETS • Poly(vinyianthracene) Is i candidate potymef, which can be made vii two routes: — From vinyt anthrscena, to maka a polyslyrtn^ika polymer; — From anthracencpharw, tornske a parytene-llka vspor deposited polymer. • The UV-Vls spectra of the potymer h« been measured, ind demonstrates the feasibility of the material. • Shells and coatings have been made from etch miteriaJ, • A new yeJJowmaterial, aWn to the orange Mrthracenophsne, has been made. Preliminary data show It may be a 'trimef* and it may well alto make a vapor deportable poly(vir»ytanthraeene). Poly(vinylanthracene) Shells by Osaka Microencapsulation Poiyatyrene + polyvinyl anthracene) While Light Photo Fluorescence Photo "YELLOW" ANTHRACENOPHANE PRODUCT Washing orange anthracenophane with warm acetone in Soxholet extractor results in yellow material. • Proton NMR of yellow Is dramatically different from orange anthrmcenophsne. Peak In CjH, region shows one kind of proton, yet shifted from position of orange anthracenophane proton. CONCLUSIONS: Pure material—(shows as minor impurity in orange anthracenophane spectrum). POLY(VINYLANTHRACENE) SHELLS BY CJH4 section is symmetric—not a dangling moHy. OSAKA MICROENCAPSULATION • Gas Chromatograph—Mass Spectrum shows Poty(vinyUnthraceM) spectrum identical to that of orange anthracenophane. At 150-300°C, decomposes to the same unit CONCLUSION* 9 Composed at same 'monomer* unit as orange anthracenophane. ROUTES TO POLY (VINYLANTHRACENE) UV-VISIBLE OF POLYMER SHOWS OPAQUE AT 350 NM AND TRANSPARENT AT VISIBLE 1J5000 80 no PC ' ! I ! janwo; i ! ' 20 tt • ! COMPARISON OF POLY(VINYLANTHRACENE) A 5 I [AOs] I! ! i WITH Al AT 350 nm \i t ! i -0.300 i I ~ ! i 240 Wswtongth 600 (UOOO I Al 1/10 p(VA) (micron) I ! (A) I r>/ J I1 ! 20 ee . [Abs] J ! \ ! V i \ | j 40 0.70 0.181 i 80 0.41 0.452 04000 i i v i i 240 Wsvttongth COO 120 0.23 0.745 160 0.135 1X>1S UV-VIS of p(vinylanthracene) 200 0.075 1J313 LOG(l/IO) 350 nm 250 nm 240 0.042 1.607 thickness 280 0.025 1.870 10 n -8.56 -1762 320 0.013 2201 thickness 360 0.008 2.450 1/10= e-' 0.5 u 246 A ANTHRACENOPHANE SYNTHESIS ANTHRACENOPHANE POLYMER VAPOR DEPOSITION JU Golden, J. Chem Soc„ 3741,1961 PV" QUARTZ TUBE IN 3-ZONE FURNACE HCI.CNjO -H20 N«j NaMcetone -42, NaCI JSL 150-200* C 300° C 2J-50»C SEM OF ANTHRACENOPHANE VAPOR DEPOSIT SE1 EHT = 20.0 KV ,UD= 17. mm" nfl'G= X 1.00-K PHQTQ= 2G.CjjT. I : 1 • RNTHRflC.EfJOPHRIlE COAT 4-30.-93. . PROPOSED STRUCTURE OF YELLOW ANTHRACENOPHANE TRIMER" COMPARISON OF PROTON NMR SHIFTS (PPM) C-CHJ-CHJ bond ingla is 120 degree*—dost to 109.(2 for «p>. Lassring stni n thin in orange anttmcenoptiafM. Pmcydopheiw (Piryttne) Anttmcenophine Aranutle -CHj- Aromatic -CHj- Wmer 630 3.04 6.88/7.72 4.17 Trfmer 162 193 M2/7.13 3M US 2M GC-MS OF ANTHRACENOPHANE GC-MS OF YELLOW ANTHRACENOPHANE 1M' « M B' ID' «' UJJl illjllll NO 110 W W W :tuli .7 T.ii 7 I, , im t* no no i»o no no LA-CP-93-141 Electroformed Neutron Penumbral Aperatures Purpose and goals i The intent of the neutron penumbra] aperature is to provide high resolution Norman Elliott and Sherman Armstrong images (better than 10 micrometers point to point) of imploding ICF targets in the Nova laser system. This task must be achieved with relatively few neutrons, approximately ltf'-lO" total fiuence. The design of the aperanne is called "inversely varying radius of curvature" w. To accomplish the precision manufacture of this complex geometry we are using computer controlled electroforming to make a copper mandrel having the desiredL c crosn s section. Los Alamos National Laboratory Thismanmdrelld s then electroplated with gold and[th tie copper mandrel leached Materials Science and Technology Division to leave the final shape in aiKoldpar gold part A similar mmethoe d nas been used to produce PZNEX aperatures in the past Improvements in the new technique , i and the increase in overall 8* AnnualTtajet Fabrication SpediHrt** Meeting length by roughly two and one-half tunes. Tne aperatures produced to date Natal Boot Graduate School show a manrimtim deviation from the desired shape of 5(tm and a marrmtTm July &S, Monterey, CA deviation from straightness of 2pm jjljjgB* a D. Rets, Design of » Neutron PeaumbraWperature Microscope with lOum Resolution, Rev. Sd. Instrmn. 61 (10), October 1990 pJlM-6 Neutron Penumbral Aperature Details of mandrel fabrication Copper wire 0.381mm in diameter is strung in a "rack assembly". This assembly allows forelectrica l contact, the rotation of the part in the baft and maintains straightness and external references during the plating operations. The wire is cleaned and plated with copper to a diameter of 0.5mm. Inspection for straightness and size are performed. The wire is returned to the copper plating bath to produce the mandrel shape. With knowledge of the plating bath growth rate (see below) it is possible by computer controlled extraction stages and power supplies to achieve any desired shape that is cylmdrically symmetric and that grows continuously larger. Dividing the growth rate by the desired rate of change in the diameter gives the extraction rate at any point Extraction rates every 10pm are precomputed using a spreadsheet and the controlling computer 10 20 30 40 50 60 amply extracts die part fromdi e plating bath based on these values. length (mm.) sired cross section of aperature (cylindrical symmetry). Note axes are drawn to the same scafe. If the absdasa scale matched the ordinate it jM end approximately 10 feetto the right of the origin. Calculated plating rate of copper bath nmim tint 1 ooalemb is run tbrouch a piste Ian tn sres 1 coulomb -1 A/sea - &24 x 10" electrons/cm'/sec. Ac copper uleoce ii to esch copper ctam pUtnd id^ilni 2 ckctfQM 634 * ltf* / 2 - 3.12 r 10" atoms/cmVsec. to nlfiilttr the number of roolcs/sec. 3.12 x 10" / 6.023 xl(f-S.l8x 10* (moles/an'/sec)/(A/cm'> the Moedc weight of copper li 61546g 5.18 x 10* * 63.546-329x10" (g/anVscc.)/(A/atf) fee density ofcopper is tS6g/au 3.29 x 10V &S6 - 3.67 x 10* (an/secO/CA/cm') To mjTTmiT* the controlling computers? accuracy in determining Ihb b&e plDiss rateo o the rsdks of wire as S» dimeter frows st twice tfci rste extraction rate, we chose to leave the total currant constant His 3.67 x 10* • 2 - 735 x lO^an/Bec-yCA/cm*) density changes asthe surface area remaining intfae bath changes. To achieve gooaplating guaEty it is necessary to Keep die current denss? The tneuured plating rate U - 75 X 10^(cm/8ec)/(A/cm^ within an operating window and as constant as possible. Extra length his difference (296) is assumed to be due to the actual plating density .vs. of wire is used to achieve this goal The above plot shows the changes leoretical density. in current density for various starting lengths of wire in the bath. 1.0 a> 0.010 aCO 0.8 g e desired £ I— 09 actual % 0.000 at 0.6 E Gold plating Mandrel leaching Once the copper mandrel is fabricated and checked for dimensional The gold parts are removed fromth e rack assembly and placed tolerance and straightness, it is gold plated. A moveable current in 'j. heated SO volume per cent nitric acid solution with a shield is positioned to minimize the length of wire plated. The wire commercial surfactant (Fluorad FC-95,3M Chemical Products below die shield and in the shield r»pH hole is using Div.) to remove die copper mandrel Initially die parts were RTV. The assembly is placed in the gold bath (Sel-Ret BDT-510) cycled between vacuum and atmosphere to speed leaching. and rotated during a plating run of250 hours. A moderate current Bccause of die high aspect ratio the process still took density of 3A/ft? is used to achieve a dense uniform coating. Slight approximately 350 hours. An improved assembly allowed the leveling of the mandrel occurs over the period of the plating part to be cycled between vacuum and approximately three resulting in a difference of 0.18mm in outside diameter (starting atmospheres. This reduced the time to roughly 48 hours. This difference is 038mm). "Chicken feeders" supply constant additions last process also allowed the part to be placed in a heated of water to the bath to maintain approximately level bath height ultrasonic bath. Short bursts of agiation were periodically during the long run. applied to aid in the removal of any small undissovled particles resulting from the leaching process. Concerns addressed Summary It Is possible that copper diffuses into gold (they form a complete solid solution). This may lead to problems in It has been shown that parts of complex geometry and accurately replicated the mandrel shape. Measured diffusion extreme precision can be fabricated using computer rates indicate that at the gold baft operating temperature controlled electroforming. Hie relative simplicity of (50*C) this process is extremely slow, A short section was this method allows rapid adjustment to accomodate a removed fromth e end of a gold plated part and wide range of differing shapes. The only requirements metallogiaphically prepared and examined in the canning are that the part be cylindncally symmetric (it is electron microscope, l ine scans performed over the gold-copper couple indicated that the signal variation was die partCToroicontimiousSy (etrMngfcfnotan consistence with Monte Carlo calculations of electron beam accurately controllable process). spreads in the two materials Still remaining to be checked is whether die gold part remains as straight as the original mandrel after all machining operations are complete. LITHIUM THERMAL TARGETS SHOT ON PBFAII Patricia S. Sawyer, KTECH Corporator Jamts It Aubert and Paul M. Baca; Saitdia National Laboratories; W. Frere McNamara, L&M Technologies (Albuqueatjue, Mexico) _ AB STRACT • Recent lithium ion ba&fp. e^gg^sM^-aii ns&uiied intricate targets to measure target physics issues. Because of the stopping peiwa*: between lithium, ions and protons, these targets significantly increased challenges for material preparation aud handling compared to previous proton shots. The greatest challenges included complex shaped gold hohlranniij, CH foams of densities ranging from 3 to 6 mg/cm3 and vacuum seals covering large areas with a thickness under lum. Details regarding assembly and characterization of lithium thermal targets will be described in this poster. Porter Session of the Ninth Target Fabricate Specialists' Meeting, July 5-8,1993/ Naval Post Graduate School, Monterey, California. Poster 14 Session I Hot Box Design for a Barrier Layer Coating Tower LLOYD C. BROWN, DAVID O. HUSBAND, and WESLEY A. BAUGH (619) 455-3087 General Atomics Sza Diego, California. 92138-5608 A new Barrier Layer Tower (BLT) was designed and constructed The BLT is used to apply a gas impermeable layer to composite plastic shells. 'The basic coating process is unchanged from that of earlier •workers ^mt the tower employs a Mhot boot" design to improve "wall ttxaSoiwaiy dt the process tube and simplify maintenance. The probk-^.with the c^iycaitjpnal design are discussed and contrasted with the solutions'expressed h>' tie nii'J Hot Box Orop Towars 155 Plan View c! Hot Box Drop Towers I G E \ T8R The temperature of the BLT is controlled in ten 2 it-tall sections. The tower wall is indirectly heated using air as the heat transfer medium. A fan circulates the air within each zone to provide a uniform wall temperature. Insulation panels are easily removed permitting access for maintenance. Measurements of the wall temperature were made to verify that the desired wall uniformity was achieved. This is a report of work sponsored by the U.S. Department of Energy under Contract No. DE-AC03-91SF18601. CH coated films were made by plasma polymerization The Effect of Process Conditions On Plasma Polymer Surface Finish Lorry A. Will S. Letts, E. Fta;on, G. Devlne, C. Moore, Ninth Target Fabrication M. Saculla, C. Collins Specialists' Meeting Target Science & Technology I Lawfcnc* Llvtimon Li Hioonil latot uory July 5 -8,1993 IHKtlMW The Effect of Process Conditions On Target Fabrication Specialist Meeting • Monterey* July 5-9.1993 Plasma Polymer Surface Finish [g THE EFFECT OF PROCESS CONDITIONS ON PLASMA POLYMER SURFACE FINISH L Witt. S. Letts. E. Feaion, S. Buckley. E. Lindsay. M. Saculla. G. Coltins, Lawrence Ltvermore National Laboratory. P.O. Box 806. Ltvermore. CA 94550 Objective: The ellect ol process conditions on plasma polymer surface finish was studied. We lound that 'We wanted control over rough and smooth surface finish Tor Implosion Increased uans-2-bulena How rate increased surface roughness. Smooth surfaces were typically dynamics 5 nm RMS while Ihe roughest surfaces were 100 nm BMS. Surface finish was cnaractenzed suing primarily atomic force microscope with other optical and mechan..:*! techniques complementing Ihe AFM measurements. Flow: The objective ol this Investigation was to determine II lh« process conditions lor plasma • In earlier work, we showed that Hydrogen and Trans -2-Butene flows polymerization could be adjusted to produce a surface having a toughness useful in laser experiments. The parameters we adjusted lor surface finish control were: transZbulene ltow controlled surface finish rate, hydrogen llow rate, chamber pressure, discharge power, and substrate temperature. These • Residence Time and Concentration parameters are wel controlled and can be varied over a wide experimental range. For the puipose of this investigation we kepi an Ihe system variables constant cn each coaler although they ate not necessarily constant from coaler to coaler. Thickncss: AFM (cans were analyzed by calculating the power spectral dtnsity as a function ol frequency lor • Surface roughness Increases with coating thickness the rough surface. We found this, to be a uselut technique !or comparing the surface finish In -RMS ~ t" experiments in which thickness, ga> llow rate, and substrate temperature were varied. We have 1 lond that plasma polymerization coatings are fractal The surface linish improves at high hydrogen flow.taw trsns-2-butene llow, or high substrate temperature. Temperature: • Increasing substrate temperature produces smoother coatings • Increased surface mobility Surface finish of plasma polymer coatings [g Trans-2-butene RMS RMS RMS flow (seem) roughness roughness roughness (nm) (nm) (nm) 0.28 89.5 30.4 4.0 0.17 14.7 0.9 0.5 0.11 0.5 0.3 0.8 11.6 23.1 35.6 Hydrogen flow (seem) 10-05-0992-3059 1IEF Reducing the (low of T2B results in shorter correlation AFM Equatorial Scan Data BSP Coatcr lengths and reduced RMS roughness m 1E-11 o o Power Spectrum • from Equatorial Scans MCWll HI >414t AFM Equatorial Scan Data HRC Coater ^ Roughness Increases with coating thickness (deposition lime) T2B 0.38 teem too H, 11.6 seem 72 mTorr 12 walls *—i.vi" I 10 t «a in tcs 10 100 1000 Power Spectrum - from Coaling Tim* (min) Equatorial Scans 111 III »> »>• ll> Ml Ityiu weitt nt.m.no Heating the substrate results in smoother surface morphology Substrate 24° Substrate 40° Substrale 65° RMS 42.2 nm RMS 18.7 nm RMS 7.3 nm l/lSi 22.0 |/|s| 6.90 l/ls, 0.96 ACSDonvviPrvsanttlo* Increasing the substrate temperature greatly reduces RMS roughness and slightly reduces deposition rate ... Microshell Generation From a Mechanically Vibrated Jet George Overturf and Steve Buckley Lawrence Uvermore National Laboratory m We have produced high speed videos of the droplets formed by a mechanically vibrated jet to better understand why this generator and the particular operating conditions we have been using produce microshells. It appears we have the unique conditions where an appropriate number of droplets coalesce to obtain both the drop size and spacing necessary to produce the correct sized shells. Droplet breakup models are used to explain how we might better generate microshells. Determination of dropslze, frequency and inter droplet spacing l|i A mora precise droplet diameter can be obtained from Weber's fomxia D- 1.89 dj tW/'FF-MJ where n la Ihe viscosity, p is the density e.nd a Is Ihe surface tension. Using this model, a 100jim Jet of methylene chloride wfll yield a 193um diameter droplet. The frequency ol the Instability (u) Is obtained by dMdlng the flowrata(U ) by the volume per drop (VJ. ^ \) = — Kr Initial Interdroplet spadng (X J Is given by cfivMng the initial udal velocity (i J by the frequency V Comparison of input frequencies Results from our high speed cinematography 19 The following table contains meosured values taken from our highspeed cinematography. Using the formulas from the previous frame, we have both confirmed Raylelgh's observations as well as predicting droplet spacing and the natural breakup frequency. II Film Drop straam stream 1x1(1 droplM * == •ST sequence dia dla(mm) length velocity ipadno X/0, == (mm) (mm) (mm) (mft) (mm) drops* N natural 0.S0 an cjorr 0.49 2.29 0.57 3887 4.60 * natural (2) 0.20 0.10 uo 0.49 8.20 0.53 4125 5.33 ? 440Hz OM 0.11 •M • S.00 rso 3.11 707 2S.29 N = 440Hz (2) (Ma 0.12 AM 5.00 t» 4.94 445 28.58 4.5kHz 0.20 0.10 4.7S 0.40 2.20 0.53 4125 5.33 EE 4.5kHz (2) 0.10 0.10 4J0 0.49 2.20 0.53 4125 5.33 t 1.2kHz 040 0.20 4J0 0.92 1.10 1.07 1031 5.33 llmunJ vakM* M = * At 440Kz the drop size does not follow Raylelgh predictions and the X/D ratio ( vf- EE Is nonsensical. This Is because the droplets are coalescing. Since diameter has * a D" relationship to volume. In order to double the diameter, you would need k to Increase the volume eight times. The high speed cinematography shows 0 € that groups of droplets are coalesced together which yield the Infer droplet i< 1mm 1mm separation shown In the table. M _L o -L H natural 440Hz 4.45kHz m § Why the 440Hz, 100mm nozzle generator works JS a This set of conditions cause oscillations in the jet length. The jet appears to Q shorten with each successive drop that splits off until after the shortest drop when it returns to the maximum length. The drop released at the maximum I length moves at the jet velocity while the drop released at the shortest point is already decelerating towards terminal velocity. As a result, these two a o' drops collide and coalesce. Probably all of the drops for a given "stroke" of a the jet ultimately collide yielding a large drop separated by a distance equal a to the number of drops coalesced. This separation is crucial for preventing a inter drop collisions further down the column. The terminal velocity for a 8 400jim droplet is about 1.5 m s'\ When it blows into a microshell it •sar decelerates significantly and at this point shells can collide. sr The drawback of this technique is that it creates a distribution of shell sizes because of inconsistencies in the number of droplets which coalesce and the amount of material lost in collisions as satellites. These satellites end up as debris in the collection dish or worse yet, stuck to the shells. "S" shaped droplet dispersion pattern Photo of electrostatic deflector Photo just below Photo at 2ft lower showing the apparatus with droplets falling deflector plates drops haven't coalesced in an "s" shaped pattern. Conclusion We are currently working on the electrostatic deflection technique. We believe it will give us small size distributions without ail of the unwanted debris. It should also give a higher yield of shells per volume of polymer solution since no drops are wasted. Another method of interest to us is Chuck Hendrick's "drop on demand" generator which should have excellent precision in drop size and requires no electrostatics to provide drop separation. We would like to acknowledge the following individuals who have preceded us in this course of investigation and thank them for their fine documentation; Chuck Hendricks, Jack Campbell, John Grens, Eben Lilley and John Wilder. TRITIATION OF POLYMER TARGET MATERIALS BY ISOTOPIC EXCHANGE R. E. Ellefson, J. T. Gill, H. B. Melke, and M. H. Sowders EG&G Mound Applied Technologies Miamisburg, OH 45343 H-G. Kim and M. Wittman University of Rochester Laboratory for Laser Energetics Rochester, NY 14623 Polystyrene microshells with D/T substituted for H are desired as a surrogate for cryogenic D/T inertial confinement targets. D«-polystyrene targets are prepared1 and selected for desired dimensions and uniformity of wall thickness. Some of the deuterium is replaced by tritium in a Wilzbach isotopic exchange reaction where beta energy from the tritium catalyzes the exchange and tritium preferentially replaces a lighter isotope on the solid. The exchange reaction rate is enhanced1 when the polystyrene is exposed to UV (254 nm line of Hg) light. Twenty-seven Dt -polystyrene shells [250 ii dia.; 4 ft shell thickness] were loaded into a 0.3 mm i.d. X 0.7 mm o.d. quartz capillary 120 mm long. The capillary was placed in a 1.8 cc quartz volume with 22 Atm-T2and UV irradiated by a 20 W Hg lamp for 92 hours. This produced 0.30 mCi/shell (400 Ci/g) tritiation of the shells measured by burning the shells in air and measuring the DTO in HjO by liquid scintillation detection. A net increase of 0.053 mole percent of DT in the T2 gas was measured. An excess of 0.032 mole percent of CT4 over the CT, in a blank test run (no shells) was also measured. Discoloration (brownish color) and insoluability in toluene was also observed for the shells. Similar discoloration and embrittlement was seen in a Mound study on beta-induced tritiation of high-density polyethylene3 and in Kel-F polymer valve seats. Assuming that the CT „ and some DT species come from decomposition of -CeD, phenyl groups lost from the solid to the gas by radiation damage, the remaining DT attributed to T exchange with D on the solid predicts 0.33 mCi T uptake in good agreement with 0.30 mCi measured. The mass balance of these measurements predicts approximately a C(D5T, polystyrene shell. 1. M. Takagi, et al., JVST-A 2, 2145(1991) 2. M. Takagi, et al., JVST-A IQ, 239(1992) 3. J.T. Gill, JVST-A 3, 1209(1985). 1 2 TRITIATION OF POLYMER TARGET MATERIALS (D/T)e-POLYSTYRENE SHELLS ARE A USEFUL BY ISOTOPIC EXCHANGE SURROGATE FOR CRYOGENIC D/T ICF TARGETS • Background - Wilzbach Isotopic Exchange Reactions R. E. Ellefson, J.T. QUI, KB. Melke and M.H. Sowders Normal Beta Driven Exchange EG&G Mound Applied Technologies Enhanced Exchange - Excitation of Receptor Mlamlsburg, OH 46343-3000 and • Tritation of Da-Polystyrene Target Shells H-G. Kim and M. Wittman UV-Enhanced Tritiation Apparatus University of Rochester Laboratory for Laser Energetics Measurement of Tritium in Shells Rochester, NY 14623 Indirect Measurement of CDT Stoichlometry Gas Analysis Mass Balance • Observations and Summary Ninth Target Fabrication Specialists Meeting July 6-9,1893 Naval Post Graduate School, Monterey, CA ^ TRITIUM ISOTOPIC EXCHANGE RATE DEPENDS ON T2 CONCENTRATION AND ACTIVE RECEPTOR High-quality, polymer shells are fabricated using an encapsulation technique demonstrated by • Beta-Induced Surface Reaction: ZnS-Aerogel Light Osaka University T2 • SiOH(Surface) HT • SiOT R - 0.02 Ci/g-Atm-Hr p • Bulk Tritiation of High-Density Polyethylene W/O emulsion R • 0.002 CI/g-Atm-Hr After 150 Days: Discoloration, Cracking • UV-Enhanced Tritiation uv g T2 • D8-Polyatyrene —^ (D/TL-Polystyrene • DT • W/O/W emulsion 254 nm UV Excites Phenyl Ring Promoting Exchange © Polyvinyl alcohol Osaka: R(No UV) - 0.0006 CI/g-Atm-Hr © In HjO ML R(UV) - 0.12 CI/g-Atm-Hr »Polystyrene This Work: R(UV) • 0.20 Ci/g-Atm-Hr solullon 6 APPARATUS FOR UV-ENHANCED TRITIATION COMPOSITION CHANGES IN TRITIUM EXCHANGE OF D - POLYSTYRENE SHELLS 8 GAS AFTER 92 HR OF UV ON De-POLYSTYRENE Componant (Mol-%) 1 Nat DeltDelia DT - 0.083 mot-mol-%* ! bVll. bVBIiVlT".oi»"«ol-V' 0.4" +—4.-..+ —* Da I la DT Blank* .£>»» mol-V* r* 0.3 0.2 Polyatyrona-D Simple Date Blank Analyala Data Hat Delta CT4 • 0.03* mol-% 0.1 Delto—a CTo 4 Blino —k o •- 0.033 mol-% O .... i1 i i i i1 i i :—i• • •••• • •I G-1 G-2 3-1 8-2 S-3 3-4 0-3 Q-4 B-! B-2 B-3 B-4 Q-5 (3-8 Samplo ID-Number or Batora + 01 Atlar Euh. • CT4 Balote » CT4 Mter Eich. N2 (BOXUNE) MEASURED TRITIUM IN FIVE SELECTED SHELLS 1, 7, 14, 21 AND 27 WERE SHELLS SHOWS UNIFORM LOADING DESTRUCTIVELY ANALYZED FOR TRITIUM Tritium In Shell (mCl) 0.4 • Shells Were Burned In Air Slowly To Form 0.35 • DTO And Minimize Any Loss As DT Gas * 0.3 * r * * Released DTO Was Captured In 50 ml H20. * 0.26 Two Rinses Of Reaction Flask Were Done. Avaraga Tritium par Shell • 0.30 »/- 0.04 mCl (2 Sigma) 0.2 - * Dilutions Of The Three Water Fractions For Liquid Scintillation Counting Were 25,000:1, 0.16 600: 1 and 50:1, Respectively. 0.1 • Tritium Recovered In Each Water Fraction 0.05 Was 99.6 %, 0.4 % and 0.04 %, Respectively. 0 I I • ••it i.i i J—i i i i i i i i i i i i i i i i 1 2 3 4 6 6 7 8 9 1011 12131416 1817IB 102021222324262627 Shell Position Number MEASUREMENTS AND COMPUTATIONS 10 MASS BALANCE OF C, D, AND T FOR A SHELL Fill Gas: Volume -1.8 cc; P-320 psia (21.8 Atm) 1E-6 (g) Gas Quantity - 39.2 Atm-cc; 102 CI T2 70 Starting Maaa UV/T2 Irradiation Produces Initial Shell: Dla. - 250 urn? Wall - 4 um Loaa aa CT4 BO C D CD T Mass (D8-Polystyrene) • 7.4 E-7 g 8 8 0.87 0.33 Mass (D) • 11 E-7 g C Remaining Mass (C) • 8.3 E-7 g SO D/T • 1.7(Atom Ratio) Gas Analysis': Change In CT4 » 0.032 Mol-% 40 C Released To Gas • 2.5 E-7 g -H--H-H- Change In DT • 0.053 Mol-% 30 D Released To Gas • 0.70 E-7 g 20 Tritium Uptake: 0.30 mCl/Shell « 0.31 E-7 g Starting Maaa Lose aa DT Predicted 'iMeaaured Remaining Mass On Target: Stolch. 10 7 D_ „ T From DT'T Uplike Mass (C) - 3.8 E-7 g 1.00 * Remaining {Exc(l() :o3 £mC I Mass (D) • 0.36 E-7 g 0.57 0 EE2L Mass (T) • 0.31 E-7 g 0.33 Carbon Deuterium tritium Total • 4.47 E-7 g (60%) 1 RESULTS AND" DISCUSSION 12 • With 20 W UV Irradiation, Circulation ol Qlovabox SUMMARY Atmosphere Wat Sufffolent To Maintain Tarsal Tamparature Leee than 42 C Over the 02 Hours. • UV Irradiation Cauaed Dlsooloratlon of Sheila And Mad* Tham Inaolubla In Toluene. Shells Ware Burnad In Air And Tha DTO Wa» Efficiently Captured In 60 oo Of H20. J Significant Trlflaflon of Polystyrene Targets Can Be • D2 Loss From Shalta Into T2 Wat Maaaurad to DT Increase. Rapidly Achieved By UV Enhanced laotoplc Exchange. A 60% Loaa of 0 from DB-Polyetyrane Ie Calculated J Direct Measurement ol Tritium la Done By Burning Targets • A Blank Run (No Shells) Gave C and 0 contributions In Air And Measure DTO By Liquid Scintillation Counting. from Quartz-Nylon-SS Apparatus To Qlve Nat CAD. • Maaaurad T Addition Of 0.30 mCl/Shelb D/T • 17. •/D/T Ratio Can Be Inferred For A D8-Polystryrene Target UV Enhanoed Trltlatlon Rata was 4.4 CI/g-Hr e 22 atm T2. From Measurement Of 0 And C Loss By PVT/MS Gas Analysis. Osaka Rata wai 3 CI/g-Hr for 20 Atm T2 and 4 fj Walls. /The Trltlated Target Survived As A Shell Bu! Was • Carbon Loaa Of 40% From Shells Into T2 Overgaa Waa Discolored From Extensive Loss Ol D5-Phenyl And D From Estimated From Gain In CT4. Large Lots of C Is UV Damage And .Tritium Betas. Conalbtant With Loss o< Phenyl Groupa From Polystyrene. • Assuming D In DT cams from Deatruotlon ol CeDsgroupi, Exoasa DT la Attributed to T Exchange. T Irom DT Exoasa Predicts 0.33 mCl; 0.30 mCl Measured. : f ^ "ATHENA" A LABORATORY PULSE POWER PROGRAM TO ATHENA DEVELOP AN INTENSE SOFT X-RAY SOURCE Pulse Power Experiments Inductive Store Implosion 15-SOMA Load Foil Explosive Generator or 200 - 500 ns Capacitor Bank I Soft ' X-RBV8 •1-10MJ 10 -100 MJ 3-6ps L Plasma Flow Switch Loa Atasoa Lata Atoroa® PROCYON PEGASUS II CIRCUIT Stang* Muckx and R 0pMtag8*Ach + PkmtoMtt BANK -0.5m£l LBANK LfUSE-12.5nH link IX Fta Cofrpnulon and [IIIMII Load ——/AW nmn Ocncrator r= Crop a 1728 pi +v 45 kV L Luid ~18nH( ' STRAP = 5 ^H '"fid" -V: 45 kV r= CBOT « 1728 (if DrtMlorA (q*ah« 8.08 Afamoa Los Alamos ATHENA PROGRAM Pulse Pojver Facility "Loads" by Los Alamos MST-7 Targat Fabrication Stall • Cylindrical Liners - Shock Phenomena Experiments Pegasus n (30%) • Cylindrical Implosion Load Foils - Radlatlon,Phenortiena Experiments Pegasus D (30%) • Plpima Flow Switch Foils and Films - Pulse Sharpening Experiments Pegasus II (30%) Procyon (100%) Loo Ataraxse STEPS TO PEGASUS TARGET FOIL PRODUCTION • Attach PVA/CH Film Target to Target Fixture HoO Here BtoflS to "Glue" (2h • Use HoO to Soften PVA and Attach to Rings • Shrink to Eliminate PVA/CH Film Wrinkles (propanol and heat) Lea ^Hamso® Al/AIX0Y Vapor Deposition Geometry GRADED FOIL PLASMA FLOW SWITCH CONCEPT Mylar Barrier Membrane 0.5 iim or 1.0 nm Thick 10 • 20 mg Mass Aluminum Flow Switch Foil Graded Thickness 20»150 mg Mass Gradient: 1/R2 PegasusH 1/R Procyon Net - I.e. Barrier Membrane and Flow Switch LefcAtomw© GRADED FOIL SWITCH THE PLASMA FLOW SWITCH im2 IS CONCEPTUALLY SIMPLE 40 rng ALUMINUM COMPENSATED FOR 10 mg BARRIER FILM - ihr Conduction Time - J^f LoadSfot (halght, h) Opening Time'^p-J^ Flow 8 witch PU»ma Calculatad- (|MS6, U) Profllt Could Barral (length, d) Outer Support Ring - BopJAw -if- 49 SO W 120 RADIUS (mm) (Los ABosmos 1 2 Doped Mandrel Production and Characterization at LLNL • Why are wt Inters Jted In doped mandrels? - Preliminary* | - Capsule performance diagnostics Robert Cook, George Overturf, Steve Buckley, and Randall McEachern • Current capabilities - mandrels: doped with CI, I, Fe, Cr LLNL • polymers: the same, plus Br, TI7 • Mandrel quality and polymer chemistry - two case studies • Cl-doped mandrels Presented by: Presented at: - Cr-doped mandrels Robert Cook Ninth Target Fabrication Target Science & Technology Specialists Meeting iVllMnlMMn ISlMMIiMnlai July 7,1883 Mandrels are currently made at LLNL and GA by solution drop tower techniques. tig Solvont .Droplet evaporation rPi Generator Skin formation S 3.5 m warm Drop Tower Shell Inflation cz 1 m o cold Final I i ooonoi product o i M 5 Mix of the capsule inner wall with the fuel during an A significant component of the Hydrodynamically implosion degrades capsule yield. ig Equivalent Physics (HEP) campaign is to understand mlfg • During the ablation of the capsula wall and concurrent compreaslon ol • Doping ol tha Inner capaula wall with hlgh-Z alemente can provide a the fuel, aurfaca perturbations grow with growth factors dependent on mode apectroacoplc diagnostic ol mix. number. • As the wall mixes with the tuel, the dopant Is Ion bed to H- and He-Ilka Ions whose amis slon spectroscopy Is relatively simple to Interpret. • Because the relative populations of Ion slates depend on the temperature end (tensity of tha fuel/plastic mix raglon, and the degree of mix atfecta the temperature of the mix region, Ar la frequently added to tha fuel aa an Internal standard. Qualitatively one looks at the relative o amounts of Ar and wall dopant emlaalon. • This leads to a mixing of the Inner capsule wall with the fuel, resulting - In a very smooth target, the Intenalty of Ihe dopanfe emission In lower fuel densities and temperatures, and thua lower yield. will be weak relative to Ar, due to little mix. • In a more bumpy target, the Intensity of the dopant'a emission win be much stronger, due to Increased mix. • LASNEX attempts to make quantitative aanaa ol tha measurements. Wt'hmif The choice of mandrel dopant depends on the details of the Implosion experiment. 3u C f • Historically, the program has used a Cl-doped mandrel as the o 3 spectroscopic diagnostic. o IH 10£ a a • New target designs, especially those which raault In higher fuel I temperaturea or those that use ablatora which are optically thick with a> o t^ 4 E 5 s respect to H- and He-like emission from CI, require hlgher-Z dopants. >. s ] o H sr f f if H • To meet this need, we have developedboth Cr and Fe doped polymers a. 14 I* that can be used for mlcroshell formation. Wa may soon be able to add f? r% s T1 to this list. f-^if I* H -7 5«5 II 3 I| ® .a c> • FT 3 W m 11 7Q5. M C € u c . p WO V • a <™ OXI 10 AFM equatorial scans of Individual targets give detailed information on surface structure. jg • A ta;get Is totaled under an AFM head to give a 2 x equatorial trace of the vertlcle displacement of the surface, which we will call h(B). • This trace can be Fourier transformed to express it In modes. h(d) = ZAke*° • The contribution ot each of the modes Is represented In • power spectrum where the power as a function of the mode, k. Is given by A,' (In units of nm"). • Talk by Randall McEachern and poster by Craig Moore will provide more details. 11 Our new equatorial AFM trace scanning capabilities revealed previously unknown surface features. yj • Before tlM development of the "surface mapper", analysis was limited to SEM or relatively small AFM patch scans. ' • Thlr focusad our Interest on short wavelength features. • The first equatorial scans of completed composite capsules with Chdoped mandrels revealed that there were surface modulations with wavelengths of to to 100's of microns that were previously unknown. • The growth of these modes during the Implosion le especially strong. • Further Investigation showed that these surface modulations originated with the Ct-doped mandiats. 13 M It Is likely that phase separation behavior Is responsible for the surface roughness observed in shells produced from blended mandrels. |3 • Initial concerns centered on the low quality of the commercial poly(/xhlorostyrene), H a*420K, M^flU^zS.2, originally usad for blending. - Fully chlorinated polymer (M W«9»K. UJU^l.t) synthesized at ULNL was u sod for blending with no Improvement In surfscs roughness. • The EDX capoblllty on the SEM was used to look for atomic composition variations In mlcroshell walla lis a I unction ol position. • Hie C/CI rstlo wae measured on both blended and copolymer shells. No significant differences between shells or spatial variations on a shall were seen, Indicating that If phase separation Is taking place, the compositional variations are small (lass than 5%) or the spatial length scale Is much smaller than theroughneae length acale. Smooth 1.0 atom % Cl-doped shells have now been prepared from a styrene • p-chloromethylstyrene copolymer prepared at LLNL ig • Synthesis: • • Analysis: M„*96K UJUam 1.6 to 1.B (monodlsperse Is 1.0, our PS Is 1.05) Atom % CI • 1.0% • A copolymerlzatlon of styrena and jxhlorostyrana has also recently baan accomplished. Cr{CO)6 with monodiaperae PS. Doping l«ve< is controlled kinetically. 1000-3 4CM,-CH>; • CLTCOW •FCH.-CHJ; . J CO • We have previoualy noted that the aurface of freahly made, bright yellow bulk polymer turns brown on extended exposure to light. Thia la due to a photocatalyzed cleavage of the Cr-CO linkage followed by oxidation of the zero valent Cr . hr •WHi-aif; Top CR* * SCO S CO CO 0.001 " ""I 10 100 1000 • The same process occurs In thln-walled mandrels mode number exposed to light Note that the Cr is not lost from the shell. mtmammm We discovered that the surface roughness of our 0.2 atom % Cr-doped mandrels Increased with age. g • Equatorial acana of a 5-montfw>(d 0.2 atom % Cr-doped mandrel stored in ambient light 800- 0 45 90 I3S 180 ZZS 270 31S 360 dagreas • Equatorial scans of • freshly made 0£ atom % Cr-doped mandrel: 800- p 1 r <5 90 13S 180 22S 270 315 360 degrees 22 ~ It Is likely that local chain relaxation is responsible for surface roughening. M • Loss of three CO's per Cr represents a significant change in the local polymer environment, whether or not the Cr Is aubsequently oxidized and/or migrates. • This will be followed by local chain relaxation to relieve the local stress. • How these telaxatloni should msnUestthemieWa* on a macroscopic scale Is not obvious, but the clear result Is an Increase In the low and mid mode amplitude!. • The Increase In the amplitudes of the high frequency modes may be due lo the formation of Cr 20, particulates on the shell surface. W e have no Independent verification of this. • See Steve Buckley'e poster for more Information on the Cr-doped polymer and mandrels. 24 Summary Acknowledgements • We (iav« prepared and characterized smooth CI and Cr-doped mandrels for use In the HEP campaign. • Craig Moore and Ed Llndsey tor characterization help. - A new Cl-doped copolymer synthesized at LLNL has eliminated roughness seen In blended Cl-doped mandrels. • Dr. Jimmy Mays and Dr. Gary Gray, University of - Cr-doped mandrels roughen with exposure to light due to a Alabama • Blrmln gtiam, and Dr. Robert Sanner, LLNL, for work pholocatalyzed decomposition ol the dopant group. on Tl-dcped polymer synthesis. • A soluble Tl-doped polymer suitable for mandrel formation ha* recently been prepared. • Polymers and mandrels doped with I and Fe have also been prepared. BOSS Motivations (or developing a process for making, spherical Preparation ol Hollow Shells Using a shells on a removeable jdepolymerlzable) mandrel 33 Depolymerizlng Mandrel - Feasibility • Allowa building a chall alerting at tha Inside surface • May be possible lo torture the Inside surface Can make large (2mm) shells - difficult by drop tower 8.A. Letts, M.D. Saculla, 8.fc Buckley, E. Fear on, C.E. Moon, EF. Lindsay « Can incorporate a wide rangeo l diagnostic elements Into shall: Stephen Letts Presented to: - Plasma polymerization (CI, Br, I, SI, S), possibly (Tl, Sn, Ge) Target Science A - Sputtered IBms {Tl) Technology Ninth Target Fabrication Specialist Heeling HIMHIHIIM Monterey, CA Mm—lUtot July 6-1,1993 A possible method for shell production uses a thermally After pyrolysls only ihB plasma polymer coaling rehialns stable coattng over a depolytnerizable substrate 0 .19 CH, CH, (—CHj—C—)« Haalr CH, « C ' WTC I Cg) polymer shell CHCosI Heal Heated at 260*C (or 48 hours polymer shall with malal Isyet Final welghl: MM Wafl thlcknasa: 13 pm Olcmeler: 490 1 3 |im MWI NX CH and CHBr plasma polymers are more thermally Problems and limitations of the removeable mandrel stable than poly (alpha-methylatyrene) g process 100.0 Thermal stability of the outer layers (heal to 280*C) -1—f——r*—rd L-4-J 1 1 1 1 sex Bunting • High rate ol gas generation sail Surface finish of polymer bead 700 ; wo - Heat in water 11 - - Solvent vapor treatment M0 \j Sphericity I <0.0 - Heal In water 30JI ') My (itlu-caediyisiyrsne) \ - - Polishing, grinding, etc. M0 I) CHBr Ptaraa Potyawr \ (0.0- Hasting tal«: 20*C/mln 0.0 1 1 1 1 1 1 1 \l 1 1 too 100.0 ISOJ mu mu xu MI 4OOJ -ISM MI KU SOU p) I Poly(alpha-methyalstyrene) Is available In bead form. The surface Is roughened Melting PflMS beads in hot water improves sphericity and sirfacs finish by fractures and polymer debris .19 * Surfactant 011 / Hater Tween 60 RB 14.9 P06,(20) Sorbitan Honostearate Ar Without Surfactant Beads aggregate at T > 82° C Top light, locus on pole Top light, locus el equilor Stir to Suspend Deeds - 500pm dlemeter Heat 78-%° C 1 Heat treating PuMS beads Improves Ihe surface finish Heat treating PuMS beads Improves surface finish and sphericity jg UnlrMled Healed al 7S'C for 10 MInutea Untreated Heatad al 84*0 for 70 mlmilea The surface of PaMS beads has many small particles Bead uniformity was Improved by heating In a which melt with heat treatment column . p (PaMS) a 1.075 g/cc Untreated Heated al 84'C (or 70 Mlnutea Column length 1 m K>j MSec pW^C] Cool Heat V -10cm/s Heal t T»140*C C AFM scan on heat-treated PaMS bead shows some A PAMS bead was lowered Into a letluxing solvent surface roughness to study the effects ol vapor treatment Insert lnSatu«-ited Vapor 1-5 Seconds Solvents Ha thyIana Chloride Toluene Hoat 1 ' A vapor trestment contactor was added to an existing drop tower Exposure of a PaMS bead to, methylene chloride vapor to knprovo the surfsesfinish o f PAMS beads ^ smoothed out much of the surface roughness (g s Bead Injector Untreated 3 Second Vapor Exposure Level of Reflux ^Hot Solvent -Shutter Hoated Colurcn 5.0 a Length 8 Zones, each at lie* C I , .'Collector Troy Surface finish of PaMS bead? is improved by solvent AFM scan on solvent vapor-treated PaMS beads shows vapor exposure In a drop tower IS excellent surface finish ' . Untreated Methylene Chloride Vapor Exposure Large spherical beads of PaMS were 3 mm shell mad6 by depolymerizable fabricated by melting ' mandrel technique Ethylene ' ool 1B8*C Mylar "120°C Heat Cool NRF 15 mln 1WC Wash H20 Coalescence ol beads by On remelllno, surface melting - one void-fret tension produces a . . .rM^met owsfcoatetl poly Ot-melhyl styrena) baad hamtapheta sphere • Ihlcktwt • 100 Iim Conclusions - preparation of shells using Rotary profllometor ecan ol PAII3 bead (malted and depolymarizabla mandrel overccated) ahowe improvement In sphericity. / • Shells can b« made (up lo 2mm dla.) • PaMS can ba completely removed (radiography, mate) J»aM3 eheDs can ba made Ni a drop lower - baa mass to remove • Controlled pyrotysls allows aMS to diffuse through outar layers wtthout bunting • Surface finish can ba Improved - Heating in wot er - Solvent vapor i PRODUCTION OF POLYMER SHELLS OVERVIEW BY CONTROLLED-MASS MICROENCAPSULATION 1. Introduction to Microencapsulation 2. Design o! the Triple Orifice 3. Overall System Configuration Donald S. Nelson, Eben M. Lilley, Lisa Cheung, David S. Soane 4. Operating Variables 5. Shell Production Video SOANE TECHNOLOGIES. INC. 6. Results 3916 TRUST WAY HAYWARD, CA 94545 Wot* dona lor the US Department ol Energy, under Contract DE-AC03-91SF1860t. INTRODUCTION TO MICROENCAPSULATION MULTIPLE EMULSIONS FOR SHELL PRODUCTION emulsions are used in paints (latex) and adhesives •styrene, butadiene, aciyllcs, vinyl chloride, etc. Shake and Toss Controlled-Mass microencapsulation uses a water / oil / water emulsion to produce polymer shells Emulsions are stabilized by PHASE 2 surfactants or other species which migrate to the interface, aqueoua polymer surfactant organic vww> TOVTO5 \/WWV particulate adsorbed ions aqueoui MICROENCAPSULATION BY ADVANTAGES OF THE CONTROLLED-MASS TECHNIQUE THE TRIPLE-ORIFICE SYSTEM Independent control of inner aqueous phase and polymer solution flows. • wall thickness Interior Fluid Stripping • inner fluid sets diameter Fluid Triple-Orifice • exterior sets wall thickness Production of uniformly sized shells. ** Orifice Control of size by (low rates. Body Polymer Segregation ol Interior & External Aqueous Phases Solution End uiew of the Triple Orifice Side View During Encapsulation DESIGN OF THE TRIPLE ORIFICE OVERALL SYSTEM CONFIGURATION ¥¥ Sieve Orifice Size V 0.010" Water 0.024" Polymer f Solution 0.070" Stripping Fluid Cross Sectional View Front View Pump SHELL DENSITY THROUGH THE SOLIDIFICATION PROCESS SUSPENSION AND CONCENTRICITY MEK. 1,2-dichloroelhane, PS Rotation improves uniformity p i&j Shells are suspended by the upward How OPERATING VARIABLES PRODUCT SHELLS FROM THE TRIPLE-ORIFICE DEVICE Process Variable Effect Interior Fluid Flow Diameter, Wall Thickness Polymer Solution Flow Wall Thickness Stripping Fluid Diameter, Wall Thickness i ""H .w Upward Flow Suspension of Shells • n-'n"'* ' Temperature Extraction Rate Hr-^lif Agitation Sphericity, Survivability -.-•.. r. \ r". 7 A" :.h '-"I." Material Variable Effect Solvent Composition Stability, Clarity (vacuoles), Sphericily Polymer Molecular Weight Mechanical Strength, Clarity Polymer Concentration Wall Thickness I P"1. rr* I PRODUCT SHELLS FROM THE PRODUCT SHELLS FROM THE TRIPLE-ORIFICE DEVICE TRIPLE-ORIFICE DEVICE I mm Outline MODELING OF MICROENCAPSULATION 1. Introduction Donald S. Nelson, Lisi Cheung, Eben M. Lilley, David S. Soane 2. Objectives of the Model 3. Conservation and Constitutive Equations SOANE TECHNOLOGIES, INC. 3916 TRUST WAY 4. Numerical Solution Scheme HAYWARD, CA 94545 5. Model Results Work done (01 the US Department ol Energy, under Contract DE-AC03-91SF18601. Objectives of the Model Solidification of Microencapsulated Shells Internal • Predict shell wall composition as a function of position and Fluid Polymer time, w(r,t). Solution • Predict the presence or absence of vacuoles based on processing conditions and dimensions of spheres. Solvent w(r,t) Initial Formed Drop Shell Hardening via Final Shell Mass Transfer • Determine the time required to solidify microspheres and the final Solvent removal from the shell wall by diffusion results in a hardened shell. of these spheres. Conservation and Constitutive Equations Solvent Removal by Mass Transfer Mass Transfer Equations Solvent Removal dw \ d 0 ^ at the Interface P(vi> +V ) L a r dr r dr a dr where w _a = pZD | o Solvent transfer R adr through the shell in R wall by diffusion in in dr out Mass Transfer Equations (cont) Constitutive Equations & Correlations Initial Condition: Mass Transfer Coefficient: krjj = Mass transfer coeff. 1 = 0 w = w D= diffusion coeff. of solvent a aO hp = density difference between drop Boundary Conditions: and surrounding fluid p= surrounding fluid density v = kinematic viscosity dw g = gravitational constant •=*in No Mass Transfer at the Inner Interface Ditlusion Coefficient - Fuiita-DoolilUe Equation: n k w t w ulk r = R a~ m( %' - % ) External MassTransferContrcl Vj = vol fractionofsolvent D Ig = ' D = diffusivity of solvent ° D0 (A + fivj) 9w A,B= parameters r=R na=-pDa-tf Internal Diffusion Control A = 0.168-8.21 •106(r-II4)2 fl = 0.03 Numerical Solution Scheme Final Equation Set Galerkin Finite Element--ln radial direction wa = £ wu = weight fraction of solvent a al node j | yZxpV&dr* = {^(VrJv^tpVV fp-linear basis functions Non-Uniform Grid Spacing U + x * dr* Finite Difference Approximation for Time Derivative J x I , , w• = "ir+Ar^i• —r t = tune dr |r*=l a At Non-Dimensionalize r where J * r-R.in tn out m , - x—R .—R. "out'",, out m Modeling Results Modeling Results(cont) Solvent Weight Fractions at Different Times Solvent Weight Fractions at Different Times t=0 t=T t=1OT 1=45T • • • 0 14 0 14 0-14 0.14 R (cm) R (cm) R (em) R (cm) MX 3 »e< IVB< 1.2. Ctchloroelhane 1.2DicMoioalhane • 1.2 Dichloroe thane 12 Dichloroethane Benzene Benzene * Benzene Benzene Modeling Results(cont) Outer Radius vs. Tims Mass ol Solvent as a Function of Tin OOMO-i •a Wo OmC 0 100 100 300 400 S00 100 time (sac) time (sac) f! m •Conclusion) Plastlc-Layer-Overcoated, Low-Density Foam Shells Plastic-layer-overcoated foam shells are fabricated Are Fabricated Using the Microencapsulation Technique using the microencapsulation technique — UH -JT Followed by Interfacial Condensation Polymerization UUB'^ • A foam density of 50 mg/cc has been achieved. • Plastic-overcoated foam shells with dimensions Hyo-gun Kim for OMEGA Upgrade experiments can be fabricated. University ol Rochester • A variety of reagents and polymers will be investigated Laboratory for Laser Energetics to make small-cell-size and low-density foams. The 9th Target Fabrication Specialists Meeting 5-9 July 1993 Monterey, CA Tit JT [Foam-shell fabrication] Foam shells overcoated with a plastic layer Foam shells are fabricated using the are fabricated by the following steps microencapsulation technique ^ - LUB-UP W • Foam shells are fabricated using the microencapsulation technique. 1. The W-i, 0, and W2 phases are prepared as follows: • Foam shells are soaked with isophthaloyl chloride-containing W1 phase: 5 g of H2O p-chlorotoluene. 0.05 wt% of TWEEN 40 (poiyoxymethylene sorbitan monopalmitate) • They are dispersed in an aqueous solution of hydroxy ethyl cellulose (HEC). 0 phase: 0.4 g of TMPT (trimethylol trimethacryiate) 9.6 g of solvent (1:1 mixture of diethyl phthalate • The interfacial condensation reaction of isophthaloyl chloride and dlbuty'l-n-phthalate) and HEC forms cross-linked HEC polymer on the surface of the foam shells. 0.04 g of AIBN 0.1% of SPAN 40 (sorbitan monopalmitate) * O phase degassed W2 phase: 2.5 -10% PVA solution in H2O mi] Foam-shell fabrication j Fonm-sholl fabrication! Foam shells are fabricated using the Foam shells are fabricated using the microencapsulation technique microencapsulation technique UP UP LLE W LIS 3. The shells are then cleaned: 2. The foam shells are fabricated by mixing these solutions: a. A beaker containing the W1/O/W2 emulsion is poured a. Wi phase and 0 phase are mixed (40°C) and then poured into into a large volume of water (1 t); 500 ml of the PVA solution (95°C). b. After the products settle to the bottom, decant the top and pour It through an 80-m filter. Pour more water through it; b. The reaction proceeds for 2 h during which the TMPT is polymerized into a cross-linked network in a matrix of solvent. c. Repeat this tour to five times; d. Collect the shells in toluene (100 mi); e. Stir well and remove the H2O. Toluene H2o nuj |Foam-shell fabrication! Foam shells in EtOH Foam shells are fabricated using the microencapsulation technique US-4*uuw. f. The toluene Is then replaced with 1,2 dichloroethane, and the good shells float. g. The good shells are collected and kept in EtOH. h. The shells are dried using a CO2 critical-point process. 3% TMPT 3% TMPT 10% PVA 5% PVA n 121 Fracture cross section of foam shells :>am shell after C0 critical point drying 2 un g Inner surface of foam shell Outer surface of foam shell 3% TMPT 2.5% PVA run Plastic-layer overcoating in foam shells The plastic layer is overcoated on foam shells Plastic-layer overcoating on foam shells is by an interfacial condensation reaction on the performed using the microencapsulation outer surface of the foam shells technqiue and interfacial polycondensation • ——— jfe Water phase with water-soluble reagent Oil phase with oil-soluble reagent Foam shell Interfacial poiycondensation reaction COCI OC,H« OH + Cross-linked polymer laver 0 Foam shell o 1 COCI OH OH CI = 0 Freeze drying -o-? Over-coated foam shell An interfaciai condensation reaction forms Reagent (a) should be soaked into the foam shells the plastic overcoating y" a — rn — LLB CtTe^F a. Foam shell in EtOH: EtOH is replaced with p-chlorotoluene. a. Foam shells containing isophthanloyl chloride in p-chlorotoluene (In PVA solution) are poured into an HEC solution. b. 4 ml of p-chlorotoluene-containing foam shells are mixed b. An HEC solution containing NajCOs is mixed with the above with 4 ml of 2-ni mol/cc isophthaloyl chloride in p-chlorotoluene. system to start the interfaciai condensation reaction. Let the isophthaloyl chloride permeate into the foam shells. c. The reaction is terminated by adding 5 cc of NaOH solution c. Decant diluent as much as passible; (10 m mol/cc). d. Mix with PVA solution and shake; d. After 1 h, the mixture Is neutralized with a dilute solution of HCI. e. Decant PVA solution and pour in fresh PVA solution. Plastic-layer-overcoated foam shell The plastic-layer-overcoateri foam shells ua are dried by CO2 critical-point process -Ufi-jflfLtlWe a. The product is washed with water. b. The H2O is replaced with dioxane. c. The shells are dried using a CO2 critical-point process. SEM of plastic-overcoated foam shell Plastic-layer-overcoated foam shell TLTSA TI13S [Conclusion | Plastic-layer-overcoated foam shells are fabricated using the microencapsulation technique - LLL;afWc • A foam density of 50 mg/cc has been achieved. • Plastlc-overcoated foam shells with dimensions for OMEGA Upgrade experiments can be fabricated. • A variety of reagents and polymers will be investigated to make small-cell-size and low-density foams. T113T INERTIA!. GENERAL ATOMICS CONFINEMENT FUSION WE FIRST PRODUCED SMOOTH COATINGS ON FLAT SUBSTRATES RELATING DEFECTS IN PLASMA-DEPOSITED COATINGS TO IRREGULARITIES ON SPHERICAL SUBSTRATES J. S. ANKNEY Presented it Target Fabrication Specialists' Meetlni Monterey, California JULY M, 1993 CENEIIAI. ATOMICS Work done for the US Department of Energy, under Coatraci DE-AC03-9ISFIS60I. GENERAL ATOMICS GENERAL ATOMICS OPTICAL IMAGES SOMETIMES SHOWED DOMES POLYSTYRENE SHELLS GAVE DIFFERENT RESULTS COVERING THE SHELL C.3 |im CH on 34 pm CH on polystyrene shell polystyrene shell August 18,199Z September 22,1992 cENcam. aroMics CCNCHM ATOMICS AN OMNI-DIRECTIONAL COATING MODEL PREDICTS DOME SIZE SUBMICRON FEATURES ARE IMPORTANT llcinu; IJIiimclor ns n Fiincllon Doiiic Diameter a> a Function ol Seed Diameter (or ol Seed Diameter lor Various Diameter Shells Various Coaling Thicknesses willi a 40 |im Thick Coaling on a 500 |im Shell. • OOBTCOJIBI •> 00 • MO Jim 0.4 M 01 0.4 0.S OB SecdtManelffftim) SMdOta»Itr(jini) ' CimiMUATOMfCf CENEBOL ATOMICS WE COUNTED FEATURES ON SHELLS SPHERICAL SEEDS OF KNOWN SIZE WERE PLACED ON SHELLS Polystyrene spheres on PVA-coated polystyrene shells 0.300 ± 0.003 |im 0.895 ±0.008 pm Size Categories (|im) Mil 1 CEIVCR/U mOMICM A MODIFICATION OF THE HEMISPHERICAL SEED EQUATION G!VES DOME SIZES aroeocs COATINGS ON SEEDED SHELLS RESEMBLED With omni-direcllonal coating, a spherical seed EARLY RESULTS Is equivalent to a hemispherical seed once I = s. Substitute R + storR 2 s lor s l-slorl In the hemispherical seed equation. CSHEBAL ATOMICS cenebm mamcm DOME DIAMETERS WERE SMALLER THAN EXPECTED A MEASURED DOME HEIGHT WAS SMALLER THAN EXPECTED K«;cd lielfjht = 0.83511 m Munsiircd dome height = 0.5 |im Substrate cuivature concctlon = 11.03 |im Smaller domes (0.3 |im seeds) Larger domes (0.195 |tm seeds) CIIIIPCICII dome liel(|lil = 0.5 |tm Expected dome diameter: 6.7 |im Eipected doms diameter: 12.2 |im Average measured dome diameter. 4.6 )tm (69%) Average measured dome diameter: 13 |int (68%) Largest measured dome diameter: 5.2 |tm (78%) Largest measured dome diameter: 9.4 |im (77%) CENERM ATOMICS cewEiMiAnMncf MANY SMALL DOMES APPEARED WHEN PVA-COATED SHELLS WERE USED PLASMA "CLEANING" AFFECTED THE PVA SURFACE L-SEl Dl!- 20.0 W l!D- 23 'n IT,;- X l.C-3 K ' 20.Dp I—— 1 ' Crri2N32 ; rvyT'i^ SHELT" L' "Ii '5 .- -.A MpmCHon PV WPS shells Peccmber 14,1992 PVA-coated PS shells plasma cleaned at 16.5 W (or 4 hours eEHBuimMucs OUR EFFORTS PRODUCED SMOOTH COATINGS ON COMPOSITE SHELLS GENERAL ATOMICS L- HI EM- ZU.O i.V u> :G ••• Z.CHpH- : — WE INSTITUTED MEASURES TO PREVENT rll;iU:il35? SI LLL III fir!?' X 10.0 t: COATING DEFECTS PVA Drop Tower GDP Coating lab Cleaned Inside ol tower Cleaned Inside of coating chamber Improved shell washing Washed and dried tube and pan Loaded capillaries In clean room In clean hood |ust before use Improved PVA filtering apparatus PS coated bouncer pan Kept loaded shells covered Characterization Stopped plasma cleaning shells 44 pmCHonPSfPVA 43 pm CH on PS/PVA Handled shells in clean room January 25,1993 March 9,1993 Acid washed storage grids TFSM93 VG's 2 Predictable, high quality coatings from different Understanding Plasma Polymer Deposition coaler platforma Is • desirable goal. Across Dlllarant Coatar Platforms Tht nnly hula plnat potymtfballon CMItr; "HBA", tied produced C9«tlng< Inferior le lh* alandafd production Irilrra ("HRC") emn oiler considerable tmpkkH iltait Equivalent poffermanca n ablilnad only aflat lully characterising and matching lha operational param«l«ta ol HRA Is HRC. . Tin ma)w considerations far coaler perforeianca In deposition rala and tenure are subelrale poehtonlng and gas IIow Mas, napactlvely. MumuMw.mmtsgm 4 Tha helical resonator plasma polymerization HRA and HRC prepare plaama polymer coatings coatar haa seen long usa at LLNL. at tha sama rale with different surfaoa texture. .B Pobmr SIScen Claw TMa rtpuwnli tht b«t «ffert ol tmpkleal sd|ustminL Ural Whaprlnclplnt la. netded ta te ga bock to mmmmmm iKmimnimiinmimim wsmwwx'UJiiiMmmmmwmm TFSM 93 VG's Each helical resonator has unlqus resonant Input RF power levels used on the frequencies and Impedance characteristics. two machines are different. .u |H»son»l«rj| s 10000 HRA HRC HRA HRC 1000 TraiNmhltrpo«fr(W) 7 1} Jiclul Timpralurt (*C) IS «- E Eflaclhrt Powir (W) S.4 S 3 100 MV, Etfichncy (%) 77 TS 10 IJ I I' HBC USA RF v 4U» 44.2 XT 20 30 40 50 v SMS Frequency (MHz) lit 11 12 HRA coatsr performance Is conslstant with Readjusting "easy" system parameters Improved lower RF power and higher precursor How rates. .U surface texture but slowed the deposition rale. HBA HBC H, Rn Rat* (•eem) St 1 12.71 HHC HRA TJB Flow Rata (teem) o.2s I \ at« Pmaure(|i) ii« * JO Tht Mitum haa iaiprentf an HRA, km Iha RFpo«tr(W) 7 v n dipoaklen nls haa StcnaMS iuMirilan|L t* lh« dlfltrtnc* rvlaftrf to rtmonmlof Of pimtfofml TFSM 93 VG's 17 The deposition rat* la vary sensitive to Equivalent coating performance has been demonstrated across sepsratt coster platforms. aubstrate positioning. .U 0.7 100 • Rat* i" -»0 _ Raughntaa la alfactttf principally by gfts flew ralta. •3 0.3 wl*ciiw* I- Oapsalllsn rata la atrengty ellKlari hy aubalialt SOJ 40 4 posklonlng, n MH U olhtr ayeUm paramatlrs. OJ * • 20 a 3m»B dllltrincia In halkal raaenalor eparallng paremalire 0.1 hn ralallvtly Hltt* Impact an tuHaei feature. a- 0 -I -4 -I 0 Ralalv* Height (mm) Sua! changaa In potlllon relative la Iht plums applicator can rciull In elgnllcent rat* changta. 19 Acknowledgments... QeiyDtirina Anaalmo DuaAaa S. Walttr Fargueon' GlanJanwaon Larry Witt iiiiHiwm«»n M.P. Saculla and S.A. Letts University of California Lawrence Livermore National Laboratory P.O. Box 808, Livermore, CA 94550 ABSTRACT Precision Nova targets will require a fuel container surface finish of 100 A or better. Several techniques to meet this requirement have been explored, including fine tuning of the process parameters on the plasma polymer coaters and temperature control of the plasma environment. Each has had varying levels of success The process described in this presentation involves elevating the temperature of the coating substrate to improve the surface finish. One of the plasma polymer coaters was deliberately detuned to produce a rough coating at room temperature. Succeeding runs were made at elevated temperatures maintained for the length of the run. Results atures above approximately 80 * C, the surface finish * Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory tinder Contract W-7405-ENG-48. Unclassified Oral Michael D. Saculla Lawrence Livermore National Lab P.O. Box 808, L-474 Livermore, CA 94550 (510)422-5891 Charged Liquid Cluster Beam Deposition and Possible Application to ICF Target Research by Kyekyoon Kim and Choon K. Ryu Materials Research Laboratory Fusion Technology and Charged Particle Research Laboratory University of Illinois at Urbana-Champaign Presented at The Ninth Target Fabrication Specialists Meeting Monterey, California July 6-8, 1993 Work supported by the Materials Research Laboratory (under NSF DMR 89-20538) and the Physical Electronics Affiliates Program of the University of Illinois. OBJECTIVE PRESENTATION OUTLINE To explore the unique capabilities of the • introduction to flow-limited fleld-lnjectlon Charged Liquid Cluster Beam (CLCB) technique electrostatic spraying and CLCB generation for fabrication of thin films and nanopartlcles of controlled chemical composition and atolchlometry, and for micropattern generation. • CLCB apparatus and experiment • Results to date (Including thin films, nanoparticles, and micropattern generation) end discussion • Concluding Remarks ELECTROSTATIC SPRAYING When the surface of a liquid Is charged to the point that the resulting electrical tension forces locally exceed the surface tension force, that portion of the charged surface will be ejected from the surface producing charged drops. This process continues until the surface tension force becomes the dominant one. Although the details of what actually happens depends on the geometry of the charged surface, as the surface charge density increases, the size of the charged drops being ejected from the liquid surface decreases. In our work, since we are Interested In achieving the highest possible surface charge density, so that the smallest charged drops (i.e., nanodrops) may be produced, we make the volume of the liquid to be charged as small as possible and the amou^ rl charge Injected Into the volume as large as •:. •: '!e (by using both the Induction and fleld-Sr- -'. • j charging), the net result being the spray c,. j charged liquid cluster beam (CLCB). Schematic of CLCB Thin Film Deposition System Mulll-let-mode field Injection electrostatic spraying of Multl-Jet-mode field Injection electrostatic spraying of ethylalcohol with Increasing needle electrode voltage ethylalcohol with Increasing needle electrode voltage WHAT IS CLCB TECHNIQUE? • It Is a flow-limited field Injection ESS plus spray pyrolysls: In a way It Is a hybrid between conventional ESS and spray pyrolysls-, however, there are fundamentel differences. CLCB Is also capable of doing things neither of them can. • It Is different from the ordinary Induction ESS: It employs a flow-limited ESS, end charge Injection Is facilitated by tisld emission or field ionization. • It Is different from ordinary spray pyrolysls: the CLCB precursor spray Is 100% charged and the size of the particles In the spray is much smaller than In OSP, namely, In the nanometer range. CLCB Is, therefore, Inherently suitable for fabricating much thinner films than OSP can, and renders itself as an ideal and powerful method for generating nanoparllcles of controlled size, stolchlometry, and chemical composition. Multl-jet-mode field Injection electrostatic spraying of ethylalcohol with Increasing needle electrode voltage > ADVANTAGES OF THE CLCB PRELIMINARY RESULTS TECHNIQUE • It Is capable ot fabricating very thin (lima and * THIN FILMS: nanoparticles. • ZnO • It allows one to control both the stolchlometry • YBCO and chemical composition of the nanophase material being processed through proper 4 NANOPARTICLES: choice o( llquld-mlx precursors • Since the aurtice-to-volume ratios of the • BaTIO] clusters In the CLCB beam are very large (due to • ZnO their small sizes), heating and pyrolysls ol the • SIOj source material can be dona veiy efficiently. • Er-doped SiOj • Iron Oxide • Since the liquid clusters are highly charged, their trajectories can be controlled using electromagnetic lenses for both particle size * MICROPATTERNING: aelectlon and/or direct writing. Precision mlcropattern generation should, therefore, be • Thin film deposition using a combination of possible with the CLCB technique. CLCB and a mask with see-through patterns. • Since two separate CLCBs with opposite • Controlled size reduction of mlcropattems charges can be produced with the technique, It Is by focusing CLCB with electrically biased possible to thoroughly mix two different source mssk. materials during the nanophase material processing. • Fabrication of nanoatructures by using nanoparticles composed of materials • By employing a conducting mask with see- Immune to specific patterning processes: through micropatterns ana by varying the e.g., use of SI02 spheres In conjunction with voltage applied to It, cne can further reduce the flIEe size of the micropatterns In a controlled manner. SEM Micrograph of ZnO Thin Film on Fused Silica SEM Micrograph of ZnO Thin Film on Silicon Substrate Temperature: 340°C Substrate Temperature: Substrate Temperature: 440°C The refractive Indices vs. substrate temperature plot of ZnO thin films U 1 11 11 1111111111 1 • IT] 11 I. 1.1 S ' i '•» •1 <•• -J 1.7 •J ...1. . • I. •. I •.. I • • • I. •. T • • •• TEM Micrograph and Mlcrodlttractogram ol Barium Titanait (MM »•»««>«<« Nanopanlcles Oepotlttd on Holey Cvbon Film T.(*ei SEM Micrograph of Silicon Oxide Nanospheres SEM Micrograph of Er-doped SiOj Nanospheres SEM Mlerognph ol Iron Oild* Nanopirllclci on Silicon Substrate • + m # # " Ullk --'-I I — I I— "••k I l— — 100 /iin 1 0 0 j»m Suborn* • iMttu Thin Film DtpotHJon ind PilWn Gmantlon System Into! Thin Film DsposWon and Pstltm QtntraUon Systsm I SEM micrograph of silica nanosphere/ GaAs quantum dots fabricated by CLCB technique and reactive Ion etching Schematic of Modified CLCB System for _ Vacuum Application > CONCLUDING REMARKS • We have developed a new method (or generating CLCB sprays of organometallic precursors which are particularly suitable for fabricating very thin films and nanopartlcles of controlled stofchlometry and chemical composition. • Since the clusters In the CLCB spray are highly charged, we were able to deposit and vary tne size of patterns on a substrate by employing a conducting mask with see-through patterns and by varying the voltage applied to It. • The results obtained to date, albeit very preliminary, suggest a number of Interesting potential applications of the CLCB technique, and we are currently in the process of explori these possibilities. • As far as the assessment of full cspsblllties and limitations of the CLCB technique is concerned, there is a large number of processing . parameters that need to be inveatlgated and optimized. In this aense, wa feel that work has Just begun for the dsvelopment of CLCB technique. Introduction Recent Progress In the U.S. • ICF program strategy Inertlal Confinement Fusion Program • Driver development Initiatives • Omega Upgrade - Nike presented to - prototype Beamlet Ninth Tergel Fabrication Specialists Meeting • Beamllne proposal • Nations! Ignition Facility by • ICF end IFE synergisms Or. Kevin W. Bleg Ottlce ol Inertlel Confinement Fusion • Inertlal Confinement Fusion Advisory Committee reviews U.S. Department of Energy • Five-Yeer Program Plan revisions July 7,1993 • Conclusion DOE Inertial Fusion Program The Inertial Confinement Fusion Advisory Committee (ICFAC) advises DOE on technical and management aspects of the ICF program V, • Advises the ASDP on program plan and strategies, recommended tWlljw IjtHm FidRf J changes, pace and scope of I he ICF program, specific technical v*n Issues, and new fecMtles end upgrades. to-i-m MSMJtMJ I 19113" • December 16-18,1992 review of time-dependent hohlraum - asymmetry for Indirect-drive ICF. td>M, myiccaliUrMi • March 8-10 review of the light Ion program. • August 25-27 review ot KrF laser program. Will review technical progress and recommend KrF program strategy and prioritization relative to other ICF program octlvltles. TfUFieMIr • December review ol target physics program will evaluate progress tern towards Nova Technical Contract objectives end sssess feasibility ol proceeding with NIF design. I —i— ino »I0 >035 tmgttphtim WKWcp«ww •nd PBFA-II is increasingly being utilized for Steady progress has been made toward target science completion of the indirect-drive target physics program In FY94/95 • Lithium divergence reduced to <20 mrad by controlling ion beam enhancement. • Lithium focal Intensity Increased to 23 THlcm* at 9 MV, giving a • ICF Ignition requirements have been confirmed by specific power deposition of >10 Status ol Driver Requirements ICF driver requirements Hfflylff^ Iw Ignition; (tan > t MJ energy (on target) 4] kJ (j»3«. I ne BiMtetength) on Nova SO kJ (protons), 25 U (IllhJum) on PBFA « • For Ignition: (1-7 HJ 2-4 ns| predicted lot K1FJ - > 1 MJ of delivered energy > 100 TWfcmZ 100-2090 TW/cmZ on Hon • > 100 TWcm2 focal intensity S TW/cmJ (protons), 3 TW/crnl (lithium) on PBFA II 5-13 ni ih»p - Inexpensive «<$200/J) < S200/J (on target) S4000/J 19 3m) on Hove llOOO/J (protons) on PBFA II • efficient (>5%) (S300-40C/J 19 3a) predicted lor HIF) - several hertz repetition rates » S% alllcltncy (on large!) 0.1% 19 V>) on Nova 0.5% (protons) on PBFA I • long-lifetime, high reliability (O.S-1% [9 3w) predicted lor HIF| sever el hem repetition rate f stiMUday on Nov* • adequate standoff from capsule explosion (several meters) 1 shot/day on PBFA S long lifetime, high reliability 1200 shotsryear on Nova («• sholsiyter) severel meters standoll ] m. on Nova IS cm. on PBFA N (< m. predicted lor NIF) The 30 kJ, 60-beam Omega Upgrade laser will The OMEGA Upgrade configuration meets all investigate the effects of hydrodynamic instability and drive symmetry on ignition scaling design criteria within the existing building space with direct drive • lllumlnallon uniformity • Individual beam-smoothing techniques • Improved mullibeam power balance • laser bandwidth pulse shaping The NIKE KrF laser-target facility will be completed in 1994 • ISI optical uniformity matches design goal • Oscillator beam Is uniform, but reproducibility must be Improved • Reliable 20 cm e-beam ampllller performance demonstrated • 5 kJ (60 cm) amplifier pulsed power adequate • Laser beama can be remotely end simultaneously aligned to e few mlcroredlans NIKE goal is 2 * 10 M W/cm 2 over 600 pm focal spot with < 2% ablation pressure nonunllormlty Near term demonstration ol advanced solid stale There are two key goals tor the Beamlet laser multipass architecture Is proceeding as part (i of ICF base technology program |g • Demonstrate that the technology advances necessary lor Ihe NIF at lull aperture • high lluence operation • multipass geometry al large aperture • "compact array" ampllller . • square beams • active switch • advanced, liber-coupled Iront end - highly ellfclent Irequency conversion • Routinely produce an output ol greater than 5 kJ at 0.35 mm In a 3 ns square pulse (beam 30 x 30 cm*) Performance mile Mom ol > 5 kJ in 3 ns at 0J5 |im on schedule for FY94 ICF Program is considering the LLNL-proposed beamllne for the west end of Bldg. 391 A National Ignition Facility (NIF), to achieve ignition and modest gain, Is an expanded concept 10B target chamber • Based on advanced glass laser technology • Facility flexibility and upgradsablflty • Multltaboratory effort in design, construction, and operations • National users facility • University, industrial, elc. participation • Multiple usege (defense, energy, elc.) switchyard Nova laser bay Project scope, schedule, and cost • 80 -140 kJ (@ 3u) laser would utilize present Nova target essets • Full NIF engineering prototype, II preceded by manufacturing Environmental and siting requirements readiness program • Allows nearly continuous operation ol Nova experimental capability during NIF construction • Useful es staging facility alter NIF construction • Maintai ns continuity In laser technology development The National Ignition Facility will address Department of Energy needs In several areas Primary benefits: The urgent need to proceed with the conceptual > Laboratory demonstration of Ignition will allow the NIF to reach design of the NIF has been Jointly endorsed by all lull potential tor delense and civilian energy applications three DOE Weapon Laboratory Directors • Retain capability for Investigating many weepon physics snd effects Issues and lor validating numerical simulation codes In a |olnl teller to Secretary Welkins, dated January 6,1993: • Provide sn effective means to help maintain nuclear weapons competence and capabilities under a tost moratorium or ban "In light ol the unsettled clluation In underaround testing and the expected value of the NIF to the defense Secondary benellta: community as a national aboveground capability, II Is Important that Ihe cost snd performance be established • Define technical requirements for future defense snd energy facilities, such aa the High-Yield Mlcrofuslon Capability and Ihe through Ihe CDR as soon as possible." Engineering Test Facility • Technology spin-offs snd commercialization possibilities "We therefore support and concur with all Ihe ICFAC (e.g, high power lasers, optical materials, photonics, recommendations and wo urge a posttlvo KD0 decision mlcrofabrlcatlon) lor Ihe NIF without delay." • Unique capability In high energy density physics of Importance to numerous scientific disciplines The Department of Energy Is preparing for a The National Ignition Facility Project organization will assure a credible and appropriate conceptual design glass laser Inertlal confinement fusion Ignition facility National Ignition Facility number ol beams 12 -18 beaimllnes (200 • 300 baamlets) energy 1-2 MJ@ 0.35 nm peak power 500 TW Intensity 500-2000 TW/cm2 pulse length <20ns beam-lo-beam power balance 10%rms pulse shape dynamic range > 50:1 (continuous) > 10:1 (plckel lence) The National Ignition Facility preliminary schedule allows Ignition experiments early in the next decade Synergisms between ICF and IFE are being developed Nuclaar MSI ban MalUm T • Target physics and technology K | M | 97 | N | (9 I 00 1 " 1 «i 1 ot | • Demonstration of hot spot Ignition and propagating thermonuclear bum Is key lo future eppllcatlons. High gain and • National Ignition FecfWy |Daslgn| Canamctm Piujiil Itl yield are then a matter ol Imploding more DT fuel mess. - Advanced targets may produce enhanced gains beyond present • ESAAB A A AAA A ignition designs. Kly Decisions KDO KOI Uvtae RM KOI K04 Ml Max MM dm Construction Oparaaoftt - Define target fabrication requlremenia and lolerances lor low 1«M d SMX MMTP^VISM Start cost, mass-produced pellet manufacture. a sit* M"« • Driver development n: mlrsH A 8ftewteflen(ESAA8 decision) Evaluation • KrF end diode-pumped solid state lesers, light snd heavy Ions • Oplics manufacturing and technology development tor NIF. • NEPA | CA A «MSI Proposed solid slate laser for IFE would have similar optical Documentation w architecture to NIF design. | EB A flccorrfotOtcMon • Reactor technologies • Safely A A • First wall and driver Interface material damage. Documanlailon man. rM • Target Injection end tracking S«(*tT Analysis Salvly ana*fi(> Docwmt OocufW* • Target and blanket material voporlzatlon/recondensstlon and chambcr clearing. ICF 5-Year Program Plan Is being revised The U.S. ICF Program continues to be a technically successful and dynamic, broad-based • ICF program strategy Integrates all program elements Into a effort cohesive national elloit with national goals • Delineates relationship of ICF to AGEX and UGT and the role of • Major technical progress hes been achieved In both tergel ICF within the Defense Programs mission with a test moratorium or physics and technology and driver technologies "no-tlrat test" policy • Program Is focussing toward a "successful Ignition • Deecrlbea the role ol the ICF program and (aclllllea lor weapon demonstration" physics, weapon effects slmulstlon, maintenance of nuclear weapons capabilities, "duel-use" technologies, snd Inertlal fusion • National Ignition Facility Is the next major step energy development • ICF program Is adjusting to post-cold war environment. • "technical contracts" ss tactical action plans which support and Increasing utilization ol ICF facilities for defense and energy Implement the atrateglc program direction applications • Possibility of Increased Industrial, university, end International participation In ICF fCFAC wilt review and advise on technical Issues ICF declassification hss been delsyed due to nuclesr nonproliferallon concerns Ionized Source Beam Deposition as a Novel Technique for Coating ICF Targets and Target Assemblies by K. Kim, D.G. Park, M.C. Yoo Materials Research Laboratory Fusion Technology and Charged Particle Research Laboratory University of Illinois at Urbana-Champaign and R.J. Wallace Lawrence Livermore National Laboratory Presented at The Ninth Target Fabrication Specialists Meeting Monterey, California July 6-8, 1993 Work supported by Lawrence Livermore National Laboratory, and the Materials Research Laboratory (under NSF DMR 89-20538) and the Physical Electronics Affiliates Program of the University of Illinois. PRESENTATION OUTLINE OBJECTIVE • Description of ionized Source Beam Deposition (ISBD) To deposit uniformly thick, highly - Fundamentals adhesive, high-density, smooth films on - Apparatus ICF targets and target assemblies at low - Potential benefits temperatures using ionized/accelerated source beam. • ISBD Research at U of I - Growth of Ag on SI02/Si: Demonstration of surface morphology control and improved adhesion - Growth of Ag on Al: Demonstration of improved step coverage - Growth of single crystal GaAs on Si: Demonstration of epitaxial thin film growth at low temperatures • Concluding remarks SPECIFIC FEATURES OF ISBD IONIZED SOURCE BEAM DEPOSITION/EPITAXY (ISBD/ISBE) Nozzle to focus and direct the source beam toward the substrate Electron beam to Impact-ionize the A thin film growth technique In which beams of focused source beam source materials are separately Ionized (partially), accelerated, and delivered to the substrate for film Electric field to accelerate the ionized deposition. source particles toward the substrate to be coated POTENTIAL PAYOFF RADIATIVE HEATHQ PLATE SUBSTRATE HEATER Lower substrate temperature Higher deposition rate ELECTRICAL CONTACT BETWEEN SUBSTRATE 0 • S kV ANO ACCELERATION SUBSTRATE Control on growth dynamics and VO.TAOE PLATE surface morphology Growth ol high-quality films in the presence ol large lattice mismetch 0 . S kV Enhanced Incorporation of high vapor pressure KM2EK materials Relaxed requirement on background pressure due to built-in surface cleaning CRUCSLE Heater, GROWTH OFAg Thermocouple ON PLANAR S102/Si USING ISBD "V.Cootng To demonstrate the ability of ISBD to control surface morphology and improve adhesion cm | Heater Experimental Conditions • Crucible Temp: 1560*0 • • Source: 99.999% Ag powder • Base Pressure : Low 10 -s Torr • Deposition Pressure : 7.5x10 -*Torr • Source-to-lonlzer 2.5 cm Distance : • Source-to-Substrate 10 cm Distance : • Adlabatic Nozzle : 7.5-mm-long cylinders, 1.0 mm In Diameter • Substrate Temp. : 110'C • Ion. Fllement Current : 2.5 A • Acceleration Bias : 0-1000 V • Deposition Time : 30 mln 1.0 Plan-view SEM micrographs of Ag films grown on SI02/SI substrate as a function of acceleration voltage. (a) Neutral source beam (b) Ionization only (2.5 A) (c) 1 kV- accelerated (d) 1.5 kV- accelerated J2 c «> BBflftf CIS •gi'l 11* iH 1» J ill !H ug I I 55 M sii« I *sO Q ffi lilt up S « N e ei a s CuO 2£ e2 o— Sebastian Push-pull Adhesion Test Set-up Si Substrate jr Ag Coating Al Mount Stub Adhesive Bond Base Plate 1.0 jim Load Plan-view SEM micrographs of Ag films grown on AI/SI02/SI substrata as a function of acceleration voltage. Neutral source beam (b) Ionization only (2.5 A) S 1 KV- accelerated (d) 1.5 kV- accelerated Adhesion strength as a function of acceleration voltage o—w« M (Ae wi * t SJOJ) e Urn InM ( t| M Al 4 VO I D c I • 1 : i c i 1 o : 1 T :110*C <> 1 Dep. Tl me: 30 mln; lonlzatl on: 2.5A ; •a • To demonstrate improved step coverage Neutral Beam ISBD '1 ~ i I D. H • ! 1 E »•« -e TSBIT •o •Mouti ll Bo m » « < 10 10 >0 40 SO Olilinc* (ram Top Surtoeo (mm) « I Bakelile Al Al > Bakelite Ag Ag 2 0f>n> Inherent Difficulties in the Epitaxial GROWTH OF GaAs ON Si Growth of GaAs on 51 USING ISBD -4.1% lattice mismatch between SI and GaAs • To demonstrate growth of high- - Polar GaAs growth on nonpolar Si quality single-crystal thin films on -60% mismatch In the thermal expansion lattice-mismatched substrate at low coefficients substrate temperatures * To demonstrate increased growth - These result In : rate . three dimensional nucleation . defects : antiphase domains, stacking faults, misfit dislocations . reduced device lifetime Growth of Single Crystal GaAs on Si POSSIBLE SOLUTIONS TO IMPENDING PROBLEMS • Ionized source beam epitaxy - Dual source : Ga, As • Low-temperature growth to minimize thermal stress . Ionized source beam : As . As crucible temperature: 296 - 300 *C • Use of energetic source beam to . Ga crucible temperature: 920 - 970 *C facilitate 2-D growth . As-beam acceleration voltage: 0 -1.0 kV - Growth temperature : 160 - 280 "C • No post-growth thermal treatment <=> Low-temperature ISBE growth of GaAs on Si Characterization of films - RHEED(/n-s/ft/), SEM, XRD, XTEM M400) Table The growth rates of the epitaxial GaAs films C«U grown on Si(100) at two Ga crucible temperatures, 920*C and 950*C at the As IMM'OO) CM Ho crucible temperature of 300*C and a substrate temperature of 280*C. The thicknesses were measured at the border of the deposited and screened areas using an a-step. M«00> C>JU<400) C"t> I . Ga-Source Growth Rate Temperature (lim/hr) CO Neutral Asa lonizeti As Accelerated As 920 <0.19 0.19 0.20b JU 950 <0.32 0.35 0.38C 40.0 (0.0 •Tha true growth rain wM) neutral aourc* beams sue much lower 2 0 (dagrea) man values In Ms table sine* tha need* ol ma a-siep was loo bfcml to accurately trace SMvalays ot Ihe nugh Mm lurfacat. "Acceleration voltage: 1 J) kV ^Acceleration voltage: OS kV Figure X-r»y duractiofl dan md RMCEO panttra of G*Ai Umt grown on ttact (100) Si al a gromli wnpanmn of 1i0"C by using (a) lonurt and aecrioaiad Ai-Mam «an Vaoc • 0£ kV and («) ntuini Ai-Mam. SUMMARY AND CONCLUSION Data on Ag coating on SIO2/SI demonstrated that ISBD improves film adhesion, flatness, and density. Data on Ag coating on A! structure demonstrated that improved step coverage is possible with ISBD. Data on GaAs on Si demonstated that film growth rate can be enhanced by ISBD and that high-quality singly- crystal films can be grown at low temperatures even when there is large lattice mismatch between the substrate and the growing film. It is, therefore, concluded that where there is a need to deposit a smooth, high-stickina. dense film on an ICF target/target assembly, ISBD is certainly a viable coating method to be employed. AFM Profilometry for Target Capsule Outline J9 Characterization =S=3 T T I I gismia • What Is Atomic Force Microscopy? • Drawbacks with conventional approach, and our solution Randall McEachern • Apparatus • Data LLNL • Analysis • Conclusions Presented by: Presented at: Robert Ibmar Ninth Target Fabrication Target Science & Technology Specialists' Meeting iwrimi Unni HHMtoMlUMnlwr July 7,1993 What is Atomic Force Microscopy? What are the limitations of conventional AFM data? M 300 A "typical* mode gain curve with a Gaussian fit. For a 0.5-mm-diam capsule, mode 25 corresponds to a wavelength of 63 pm. • Beam from diode laser redacts oil cantilever, generating a signal proportional to cantilever deflection. 20 40 60 Mods number • Tip is pressed gently onto surface, deflecting the cantilever. • Due to the curvature of the capsules, the scan size is Dmited to -60 pm by the vertical dynamic range of the AFM. Mode numbers lower than 25-30 are • Feedback circuit maintains constant deflection (i.e., tip force) by adjusting the unmeasurable. lip (or sample) height while the lip moves across the surface. • Piezo non-linearities create significant distortion in the scanned image, reducing • The output of the feedback circuit is proportional to height- raslering the lip over the accuracy ot the lowest measurable modes. a patch on the sample generates 2-D Image. BUT...Ior modes at the peak of the gain curve, the combined rms amplitude must be less than -10 nrn to avoid unacceptable mixing. Resolution: up4o 2 nm lateral, 0.1 nm vertical => modes must be measured to -1 nm Dynamic range: 4 to 5 microns The vertical sensitivity of the AFM must be combined with the ability to measure long-waveienglh modes A new technique Sample is rotated under the stationary AFM tip, giving a line scan around the equator of the capsule. Advantages: • All modes above one can be measured. • Because the lip does not move laterally, the data are largely tree ol piezo non-linearities. • Apparently non-destructive: capsules can be characterized before being shot. Disadvantages: • Requires a high-precision bearing for rotating the sample, and very stable translation stages. • Fully characterizing a capsule requires many traces with different sample orientations, which is very time consuming. Analysis of AFM trace data J!3 Each trace consists ol 3600 points (height vs. angle) 1) Data are interpolated to yield 4096 values. 2) The power spectrum is computed. 3) Power spectra from several traces on the same capsule are averaged together. • Currently, traces are collected for three orthogonal orientations of a capsule. 3 to 9 parallel traces over a 40 |im band are typically taken at each position. If the data are to ba used to predict capsule performance... t) The averaged 1-D power spectrum Is converted to a 2-0 mode spectrum 2) The 2-D values are used as Input to a LASNEX simulation Simulating the experiment What are the measurement statistics? m JS 1) Take a 1-D power spectrum that could reasonably reflect an average of many Computer simulations Indicate thai for modes 10 and over, multiple traces from a capsule. measurements of the power in a single mode follow a simple exponential distribution. 2) Convert the 1-D spectrum into a 2-D mode spectrum. The general distribution P(iaVg) for the value of a mode I obtained by averaging n power spectra is: 3) Using the 2-D amplitudes and a Gaussian random number generator, assign values to the coefficients of the Yj" 's for 1 < 7 < SO. P('avg) = (n-1)! 4) By evaluating the resulting sum of spherical harmonics at points lying on a great circle of the sphere, a simulated equatorial trace is generated. mean = - standard deviation = a •Jna Many such traces (randomly oriented) are computed, their power spectra are obtained, and the variation of each measured mode is examined. The function P for n=1 to 4, a=1 (i.e., mean = 1) Conclusions • Conventional AFM images provide quantitative height information on length scales up to a few tens of microns-insufficient for predicting capsule performance. • AFM profilometry provides the ability to measure surface features on practically any length scale, while maintaining the same height resolution. • The accuracy ol measuring a particular mode improves as the square roof of the number of traces. PRODUCTION OF RANDOMLY ROUGH INTERFACE. j ROOGH PLASTIC DISC FITTED TO HllMH.ll END. OF MICROMACHINEO The Measurement of Randomly Rough Surfaces CYLINDER *n Fmr'nnpgts hYffmfff^' ^^fiffiWinlPf MIcrowcopy U.v.UGHT POLYMERISATION 4 C. J.HonAel& d T. J.Goldaack IMERSION A SERIES OF BATHS DESONED TO DISOLVETHE PLASTIC DISC AND TO EXCHANGE THE SOLVENT. WW . wwS 2nd CYLINDER FITTED ON AND FOAM ,wwWW«' FILLED. POLYMERISED AND SOLVENT ,WWH' EXCHANGED IN PREPERATION FOR ..WW" CRITICAL POINT DRYING. m G= =0 Figure 3 Figure 1. CONFOCAL LASER SCANNING MICROSCOPE RICHTMYER- MESHKOV MIX EXPERIMENT PROPOSED TARGET DESIGN _ 400|an . *\S\NSNNNSN\\N\V G p • CRYST1C RESIN CYLINDERS 1 50 mg/cc CI LOADED FOAM • 200 mg/cc S LOADED FOAM • PARALYNE'C' ABLATOR RANDOMLY ROUGH INTERFACE IAJIII ULKJCUUV60 1/U-tL.i^ LENS 5X iax aax sax loax KA. 0.15 030 OJSO CWS OSXi REB 25 1.3 0.76 0.45 042 (um) FOCUS I00X LENS 20X ZOOM 2QX LENS JOOX ZOOM DOTH 7.0 13 0.63 022 020 (um) 1 65um rms 3.74um rms MAX. FIELD 2400 1200 000 120 OF VIEW xxx (um| 1420 710 3S5 142 71 2 Ox ZOOM SEMI- ANCZ2 9 18 U0 56 64 OF INCIDENT CONE C) COMPARISON OF 100X OBJECTIVE AND 2QX OBJECTIVE INTENSIT f MAPS Figure 7 Graph ol In lrmsl Surfacn Rirunhflfffll V 7nnm Magnification EFFECT OF SHAPE OF OPTICAL PROBE ON A SLOPING SURFACE SX Objacilva LOW NUMERICAL APERTURE LENS 10X Ob|*etlva 20X Objective SOX Ob)«cllv • Column J • UMHIl I00X Objective • Cfltunm 4 • Cakamt « CcAjmn I Zoom Magnification FICr 11 I'lgurc 10 Comparing the "jigsaw" image with a 20x obj 55x zoom image Comparison of line-outs from Fig. 9 shows a good shows the improvement in image quality obtained by using "jig correlation between the two sets of data, indicating saw" images rather than low-magnification objectives. the high fidelity of the "jigsaw" technique rms = 5.53pm Image 2 (jigsaw): 53x obj, 49x zoom rms=4.17|im F/fcl Comparing the "jigsaw" image with a 50x obj 20x zoom image shows that small contiguous areas can be successfully "jigsawed" together to reproduce a larger area. rms = 4.07pm Image 2 (Jigsaw): 50x ob|, 49x zoom rms = 4.17pm Height (jim) > 1 ro n o "•in 2 — c 3 g-g-o S 3 o V t» "« o (C2J3 2.Q£-. ^o 2 ~ - D) v<- 3 CD OP O 3 ^ C § |jf » w (D O 05 (Q 3 CO M -n fnnriirtcn-i We have shewn that the Laser scanning Microscope can be used to adequately characterise rough surfaces of the order of 5 |ixn ima surface roughness, provided that 1. The high numerical aperture lenses are ustd to linage the steep mlcrofeaiures in such surfaces. 2. Areas larger than that normally Imaged with the high NA. can still be measured using the 'Jigsaw* technique described above. 3. the use of the high NA. lenses In conjunctiva with the 'Jigsaw* technique provides better data than the lower N.A., larger field of view lenses. However, many challenges still await us in the characterisation and production of polymer foams for a Rlchtmyer- Meshkov mix experiment I I Miniature Bouncer for Microsphere Coatings R.D. Bohvmw Ninth Target Fabrication RJ. Wallaca Specialists' Meeting EJ.Halah Iffl Lawianea Livamioro July 5 -8,1993 113 National Labenloiy Rick's poster 1 2 THE CHALLENGE Various types ofoouncer pans have been used for depositing uniform coatings onto ji-spheres. The 'initial piezoelectric type t sed a hollow cylindrical ciystaj as the This Poster will report on the development of a new low mass bouncer design uti- driving source. The speaker coil type was later developed for heavy spheres (e.g. lizing a thin piezoelectric crystal disc.The disk is mounted directly onto the bottom solid balls). Both drivers are inefficient and require costly power amplifiers. Fui^ of the pan where Ihe p-spheree are ratting. The crystal b oriented to give the pan an ther, they are bulky and not suitable for some applications A common bouncer de- up-and-down motion. Because of it's small size, we have been able to install the sign problem is controlling the motion of the spheres, particularly at Ihe initial bouncer pan inside LLNL's Parylene coating chambec The miniature bouncer con- coating phase when they tend to stickto the pan or to each other. In general due to struction and some of coaling results wiU be presented. their large masses, and poor coupling, past bouncer designs have had significant dampening that results in a lack of motion controL WfrVTnrgrcfnrcW^WiWWW&^n cxmAiTVYBfiMws 3 Results: Conclusions: Proven Reliability Steps sre currently beinj taken to lest tie Mini Bouncer Has baan usad in Parytono coaler in other coring systems. Inthenearfotorelvter Picxo Discs will be invcstipied for large bouncer pan taagc. Produces pinhole fraa AL coalings on Shells Other applications for Piexo Discs sre being looked into, nch ss a Drop on Demand Drop- let Generator. Allows precise placement in coating systems Good reward! tool lor coating development Now Mini Bouncor Schematic Present Crystal Bouncer Schematic Function Generator AnpHier White Nom 1-100 Welti Matching Network Al Bua PUt* Advantages Highly efticMnt Low power r»qu»em»nl» Small In tin Low coot No need lor matching network Operrfae on ting la Irequency > RANGE EXTENSION OF INTERFERENCE WALL THICKNESS MEASUREMENTS Donald H. Beighley and David A. Steinman RANGE EXTENSION OF INTERFERENCE General Atomics > San Diego, California WALL THICKNESS MEASUREMENTS We have developed a method that quadruples the wall thickness measurement range of the Jenavert interference microscope. Using this method, we can measure walls ~60(im thick on ICF capsules -500 |im in diameter, with reflectance interferometry. We double the thickness measurement range by positioning the > sample mirror approximately 1 cm below the focal plane at'the Presented by: microscope. In this configuration, the microscope effectively operates in the transmission mode and capsule fringe count is halved. Don Beighley We further double Ihe range by placing the capsule adjacent to the joint between two touching coverslips having different Dave Steinman thicknesses. We then interferomelrically measure the fringe > shift difference between the coverslip "step" and the capsule. We add this fringe shift to the fringe shift resulting from the General Atomics, SanDiego, CA "step" to determine the capsule's fringe shift and wall thickness. The effectiveness of this technique for measuring thick-walled, composite shells will be discussed. Work prepared under Department of Energy Contract No. DE-AC03-91SF18601 One day, our measurements of a batch of shells indicated they were far too thin. » We had accidentally inverted the mirror and doubled the wall thickness range! i i Going to the single-pass mode halves the The wail thickness measurement range shell's fringe count (phase shift) was limited by the Phase Shifter. Double-pass Image of ehell The Phase Shifter adjusts the optical path length of the reference beam. Phase Shifter full open Reference Beam Single-pass Image (half the phase shift) The Phase Shifter could only match the optical patlr length through thln-walled shells. Wall s 15 urn We conceived of the idea of We used coverslips to make a "Range Extender" our Range Extender. We needed an optically flat, transparent slab -30 fxm thick. The Phase Shifter couldn't (So microscope could measure it.) match the optical path length through thick-walled shells. \_ o Wall >15 fim It was much more practical to make a step out of coversllps. . Adding the Range Extender matches the optical path length. 30 |im step Range Extender \ -190 jun thick - 160 nm thick # 1i/2 coverslip MS > Measurement range quadrupled to - 60 urn wall thickness > • > > » WJS& IM/tCJI Interferometry Is Being Evaluated for MwJOm> Examining Surface Finish of Capsules. Both global and local surface quality must be quantified: SURFACE CHARACTERIZATION BY INTERFEROMETRY • Sphericity - low order spherical harmonic l-modes Jon Larsen give overall shape Cascade Applied Sciences • Roughness - high (spatial) frequency structure Don Bittner measures dents, digs, and scratches W.J. Schafer Associates Interferometry has potential to examine nearly 4n of surface "rapidly." Hardware/software combination can make evaluation process almost automatic. Work dole for the US Dcpirtmeol of Energy, under CooMcc DE-AC03-91SF1I60I Ulf/CJL Full-Sphere Measurements Have iMilCM A WYKO 6000 Interferometer Was Been Made on cm-Size Objects.* MMJOmS- Used to Measure mm-Size Spheres. reference surface These measurements are based on subaperture optical testing techniques; large areas can be probed in relatively f/1.5 spherical lens short amounts of time. Fizeau pellicle interferometer Full-sphere analysis was limited to P^(cos9) < 6. target sphere Can this technique be extended to higher i-modes on sub- millimeter-size spheres? or The f/1.5 lens samples only 2.6% of 4n . 'Day, R. D. and Lawrence, G. N., Precision Engineering, 11,3 (1989). The Optical Path Difference (OPD) WJS& Is Found by Electronic Phase-Shift. WJS& Raw OPD Data Contains Alignment Errors. The relative phase of the reference and test beams is read out from the detector for eachrc/2 shift . Then at each detector point (x,y) A326452 B090452 A(x,y) = l1 + l2Cos 4>(x,y)+7 4 , 7t B(x,y) = l1 + l2Cos 4. C(x,y) = I1 + l2Cos (j,(x,y) + 5f 4. and the phase-shift is determined by 1 C(x,y) - B(x,y) Hx,y)= Tan* 1500 nm OD 552 nm OD A(x,y) - B(x,y) Stainless Steel Ball Opaque Plastic Ball Subtraction and division cancels fixed pattern noise and gain variations across the detector. IM/ICA Alignment Is Corrected by Removing M Corrected OPD Data Is Ready for Analysis. yyjQ.:- Low-Order Expansion Terms. WJSli- The surface may be represented as a series of spherical harmonics W,(e,4>)= I Ia,mY,m(e,4.) *=0 m=-* where 1 i Y,m(6,(l))=P? (Cose)e ^ 2 2 Minimize a = -J z {ws(e, to get coefficients a/m. D[0,cj)] is the OPD data. Then the lowest-order terms are subtracted: Y00 is piston Y10 is piston and focus YV1 and^Y1f1 are tip and tilt 8 WJSZ- Lineouts Show Detail of Reproducibility. difference of A326453 A326452 and A326453 Row 145 Column 145 ANT NW»M' o = 0.0004 |jm Each "Image" May be Processed 11 WJS& How Good Is the Data? m WJSA- to Yield a Spectrum of "Modes." System noise: Measurements on "difference of A326452 and "Modes" are obtained from Fourier transform of a lineout. These are NOT P^'s of the sphere. A326453" suggest an RMS noise level of 4x10"4 urn (or -2%). A326452 - Row 145 Amplitude measurements: Vertical resolution accuracy is ~ 0.002 nm which agrees well with the manufacturer's spec of A/300. Transverse measurements: Lateral reproducibility is ~± .1 pixel; this corresponds to ~ ± 0.05%. We are looking at other (statistical) techniques to refine these estimates. WJS.1- For an f/1.5 Optic, We Estimate 12 I/I//CjI Interferometry Can Be Developed for Ij, 13 MVIodes > 10 Can Be Seen. wvjj.:- capsule Surface Characterization. ^ The lowest ^-mode corresponds to one "cycle" For mm-size opaque spheres, we have demonstrated across the image; a great circle in an image spans about 1/10 of the circumference. individual patch measurements and data analysis yield sufficiently accurate values for surface characteristics. The highest £-mode that can be seen is estimated from requiring a "feature" to be at least 4 pixels • individual features are easily tracked from image to wide; 4 pixels correspond to ~ 1/585 of the image circumference. More work needs to be done on "overcoated" polystyrene spheres. The proper way to get £-modes is to fit a series of P^ (cose) to great circle data. 14 WJS.1 Significant Questions Remain. 1. How do we put together these OPD plots, "patches", to gather the information we want on the whole capsule? - To determine the low-order l-modes (for example, £<10 for the f/1.5 lens), the patches must be indexed properly. Offsets in patch alignment could generate artificial features. 2. Can interferometric techniques be extended to transparent capsules? - This technique demonstrates the use of interferometry on opaque surfaces. We have not attempted to analyze data containing information from more than one surface as would be the case for a transparent capsule. A New Plasma Polymerization Coater for ICF Targets. G. Devine, R. Brusasco, R. Cook, A. Duenas, G. Jameson, S. Letts and L. Witt Lawrence Livermore National Laboratory Introduction We are faced with ever demanding polymer coating requirements for use in Inertial Confinement Fusion (ICF) experiments. We have created a new plasma polymerization coating system with the capability of producing a wide variety of different types of coatings. Topics covered are design, construction, and use of just such a coating instalment and its possible use to increase our understanding of plasma polymer coating fundamentals. At the outset we recognized that much of the existing gas flow and pressure components in use would prove suitable for our task. Paramount to this consideration is the implementation of a computer control and data acquisition system which would allow us to study the deposition process over long >150 hour times and safeguard the coated mandrels against a catastrophic loss. In addition a comprehensive evaluation over the >150 hour coating process. This computer system is essential if we are going to be able to do postmortems on previous coating runs. (Photo. 1) Design features The design of the resonator system is covered in (Fig. 1) and Photo 2. The data acquisition path for the existing 37 data lines is covered in (Fig.2) Mass flow control of the very low flows used in plasma polymerization are accomplished using Conductance Flow Elements and pressure measuring manometers in conjunction with process control valves and their associated control electronics. These devices were left unchanged with the exception of a command closure feature to be used on emergency shutdown. Stainless steel construction of the various gas handling systems is used throughout the coater. Elastomeric seals were eliminated whenever possible. A Residual Gas Analyzer (RGA) was placed on the exhaust gas stream directly after the reaction chamber. The RGA allows one to check for system integrity before the deposition operation is started where identification of impurity species is possible. Operation of the LabView control program is via touch screen (see Fig.4, Photo 3) Included is an alarm set module (Fig. 4) which monitors*parameter limits. An uninterruptible power supply supports the computer, monitor, valving solenoids, and chamber vacuum measuring device. Operator control system Manual verses computer driven valve sequencing is available to the operator from the touch screen. (Fig.4) The manual mode is designed for various maintenance and short run debug operations. The computer control mode is designed to give the operator a basic hands off prompting for operation and sequencing of the valves. Data acquisition and control Use of the computer data acquisition allows the operator to monitor all system parameters to determine the source, time of occurrence, and effect of a transient, in analyzing the fluctuating room temperature effects one can see it directly influences the net R.F. power delivered to the plasma and subsequently the fractionation rate of the polymer species, (see figures 5 and 6) Eleven percent decreases in net R.F. power have been recorded from room temperature excursions. (Fig. 7) The normal data gathering function records data every twenty minutes when all the parameters are below their transient thresholds. If a transient limit is exceeded data is collected every two minutes. If an alarm threshold is exceeded the system automatically shuts down and protects the microshelis until the alarms are reset. As with all vacuum systems, adsorbed water is a sizeable component of the residual gas species. This effect is an important consideration when desiring a "steady state" condition which is essential when doing short. (< 7 hour) development evaluations. (Fig. 8) In the eighteen months of operation the system has proven itself to be a reliable system in production which has aided us in our fundamental understanding of the plasma polymer coating process. m WMWJ/WUU^fUMIWmstltSUi^ Active *ouch screen display r £ji File Edit Operate Controls t:(utcti»ns Windows Tools HDI l^MnWlpMMllaMG* : : 5mtaJ>»Uy qss* 0.077 1 Fareline cold trap Photo 1. Helical resonator coater "A" c.w. computer acquisition and control, RGA and flow & pressure modules, resonator and hood, R.F. power modules Photo 2. Helical resonator with ball transfer system in backround tk Photo 3. System touchscreen, computer acquisition, and control, R.G.A. and flow & pressure modules Photo 4. Gas manafold layout in flammable gas cabinet Poster TS 93 7 .m Warms are set on various parameters le. flow, pressure, power, partial pressure ana emission. I*., Poster TS 93 10 11 12 13 H m r* •—• S L ^— — • Laboratory thermal gradients affect net R.F. power Water desorpUon vs Masses 2,18,41,56 GENERATING ROUGH SURFACES Polvmcr mist ciiambcr ON CAl'SULES UY I'OLYMEK MIST DEPOSITION' .LS Stntn R. B«tWj, A, UtU tU HwatM t. tyt I'ahrrM* W CMmi*» Ltwrrm UtniNfrNilwutU^Mfrt fjO, S«* UtiffMTf CiWHitfl 1*ltt jjm-.- momu.. •ami utytul JAVrUCAMliCL n Btm^nt \ rvMr» \ \ Tar liydroUynamlc *faMify experiments trc waif (0 be able to modify the lurfaer h flrti.lt of tew targets. An ultrasonic spray u«J to gtwrate droplets of potymcr I / solo)Ion that wetted (Itcnubsf rate and dried 10 furm bumps, cuss nit norm fhimp wc wai jtudicd for a range of <«pcr»m/niaJ parameters irduiiin; tofaifon concentration, time of cypmvrt and temperature. 7/rr hump »;/<• was mwi easily tuntrolled by rJunjin^ the p Hump size was controlled with polymer concentration .13 Spraying lime was used to control bump size .13 ; < mo? J00. 0-5 \ - V-i,. 0 -3 ) 5, oAOOi c ). J*o , / 'o • ^ • •>?., ) •) . -yJ < i > > y i«. J 1 .O v.y • • • • \ * I s > : > J ' V >>> , v. -y > J 3.0 (i o .0,0/0 i. 9 r •• •• P.&&4&3 L. Added spraying resulted in dissolution and coalescence of bumps Qa Droplet profile is lense shaped .LS [33 "V- a • "•""•ryi '.V j 1 L m e: r Bump length and width were measured with the AFM .13 Bumps were sprayed on a slalk mounted shell [J) 1JJ • • 1.00 • 0,75 OJC • 0 m o Sill 0.23 a 0 • SI #2 0.0 9 X * « a 19 . 12 14 U MlDTIMuml nr.ioRi; AFTI-lt ( " • ' Conclusions [JJ An iiltraMinic nniile can be used to generate a mi>t of puijmer solution fur depositing bumps. Dump site is a function of polymer concentration, \apor saturation, lime of etpoiurc. substrate heating, and coaling chamber conditions: ( baffle, substrate placement). Iluinpt were jprajed onto targets »ith sizes IypicaJlyOJuin hi;h and lOum wide. f :V .13 Chromium-Doped Polystyrene for A reeenl requirement for ICF largel eaptutr* ii I© incorporate dopant Cr atoms iat.k4 inner Capsule-Implosion Diagnostics larpei nail. Tlie Cr allows for a sptctroieofilc dia-nouic of the initio* of the fuel at: rapiute maierul durin- ihe implosion. PrcwM te J Cr is placed near the fuel lo study implosion characteristics .13 .13 The rc;iction ofpolvstvrcnc uiili chromium licxacarbonjl result in t; in the loss of three c:ii'b(iii.imiiio\i(lc iimlcculc; mill (lie courtliiKitioii oT the rciuniiiing Cr(CO)3 (•h-an„ I On.... (aii-cii),, co / +3CO fa Cr-CO \o I L s*- 111 spcctra comparing polystyrene PS/Cr(CO), reaction apparatus .13 with Cr-dopcd polystyrene L3 /j rv n ;fr !«l ! ti»CTTO"< VtlMl « ' l ft (flirt* ••« tlx r» en M7I H.1 m 12H CI W I EDS (Energy Dispersive Spectrometry) Weight loss determined Ijy degree of scans confirm the presence of chromium Cr substitution on polymer chain _ Li! in the polymer .13 pit HurtiUTiitiO *' ii£aFfi non 0.It ATOM c CUI-flU m.k K(|ii;ilori:il traces slum* Cr-dnpcd r mandrels lieeoine roo^li when Calihrniion curve for Cr» Msndrcli lltftd I* d»ri MaMlrrttti*«*4M l»sM • Krf.'i&MwC • UOfT. tOh—<« V Conclusions Wc can produce chromium-doped poltnicr up lo oncalomrc Mandrels li.ne been produced frum lliis pohmer ' and arc suitable for use in implosion experiments • Chromium stability is affccted lit lijlit L Ball Extractor System for Helical Resonator Coaters Anselmo Duenas, Gary Devine, Glen Jameson and Ray Brusasco We have installed a ball extractor system on our helical resonator coater. This system enables us to extract a single coated microshell without breaking vacuum and thus exposing the shells to an unclean environment. This capability will also enable us to monitor coating rate and surface quality during long coating runs. The system consists of three major assemblies, a vacuum system, a video observation system, and an optical trigger assembly. Ball Extractor System for Helical Resonator Coaters* Ball Extractor-Standby/Remove Mode * o Ooubl* acting •ir cylinder ^ •V-closed Ball Extractor - Probe to. Resonator Optical Trigger Switch Assy. Vacuum pump 0 4CFM Qty. A ca. r& A To Ball Extractor System -I •V-dosed Houst air OlOpjl •Valve Slide Assy. ( Note position ) Ball Catcher Ball Extractor-Extraction Mode IS Doubta acting Ball Extractor Probe •lr cylinder ^ 'V-open Optical Trigger Switch Assy. Vacuum pump Qty. 4 ea. 0 4 CFM t A •V-closed Housa air O 10 p«l Anselmo Duenas Gary Devine, Glen Jameson and Ray •Valve Slide Assy. Brusasco (Note position) Target Science & Technology Urfyinr/otCiBorm LED Switch Sensors Optical Trigger Switch Assy. Gncral Description This devicc transmits tight from a GaAs infrared emitting diode to a Helical resonator coating system "A" silicon phototransistor. Both semiconductor elements face each other with ball extractor system in place across a 0.1 inch can. The milmit transmitter shuts off when an chioct (in I'riMluclioii »f Mfcrncncnp.iiiliiinl I'ulyiiirr Shells wlilt I In- Trijilc-Oriflcc Coiilrollcil Maw tyslcm Lisa Cheung, Men Llllcy, Dun Nclsuit mitl Ihivltl Xutme Soanc Technologies, Inc, 39! 6 Trust Way, I lay ward, CA 94545 | lar two iii*| Die c Tt>c system consists of a uiple orifice droplet generator installed on » 4 foot hifh conical column. The droplet generator is made of three concentric orifices. The innermost orifice supplies the interior water which shapes Ihe shell. The neit orifice delivers • solution of polymer thai bccomcs iht shell wall The outer orifice carries wiler thai maintains the pcsiiion of the drop during formation and also strips the newly formed sphere off ihe tencreiot. To improve shell concenutoty and tpherUUy, waur jcu ate used to ajitaie the shells. By felting the flow rates of all fluids, shells of different sizes can be produced L* a controlled manner. An upward flow of PVA solution in the column is used for particle suspension. Tlie PVA solution is recirculated through (he use of an external healed reservoir and a centrifugal pump. Hie temperature is ramped slowly from 40 *C to ?S*C to facilitate solvent re mow*! As the solvent is extracted from the polystyrene solution into the water phase, ihc .- shells becomes lighter and are carried over the top of the column and E.' collected on a sieve for harvesting. r M tn addition to the development or the controlled mux microencapsulation process, a Fortran computer model is being implemented to predict MicrophotographofaTypical Microencapsulated] composition of shell will as function of time and position. This model guides the production of shells by analyzing effects of different parameters Polymer Shell by Constant Mass System on the quality of shells. Encapiuiauon rroces* Triple - Orifice Droplet Generator in~operation. Liquid Jet Stirrers, and Product Encapsulated droplet being lorr DESIGN OF THE TRIPLE ORIFICE lip ol triple orifice Orifice Size Non-concentric encapsulated droplol 0.010" Water o Encapsulated droplet centered I 0.024" Polymer spinning induced by rolalion Solution 0.070" Stripping Triple-Orifice Droplet Generator Fluid Cross Sectional View Front View Solvent ditfuses Into PVA soluti leaving behind a hollow polystyrene sphere work done lor the US Deoartmenl ol Energy, under Contract DE-AC03-9iSF1860l. o Liquid Jet Stirrer System Overall View of System Shells Curing in Tapered Column (14 cm. IVtri Dish) Typical Production Dish Microphotograph of a Typical Microencapsulated Polymer Shell by Constant. Muss System Sul*cot Weight FriKliims nl DtlTcrcol Tunc* Ul) tst n icmj • • t.2 Oicruofoomant 1.7 D i H R (em) • HtX * t ? DcmcMtnani 1.2 Ocnwocirw* • Oo^Jt^ liwutt* Outtr Rgd/ut v«. Tfme Of So/vt/ii Magnification =J00X time |sec) Shells size =1-3 mm Titanium Doping of Polystyrene DuPont TYZOR TE and titanocene dlchlorlde were selected as complexed Ti groups for their ability to George Overturf, Robert Cook, and Robert Sanner react with carboxyiic acids to yield ester linkages. [|3 IS Gary Grey and Jimmy Mays Department of Chemistry, University of Alabama, Birmingham / CaH, In support of the Hydrodynamic Equivalant Physics campaign, considerable effort has gone into creating a soluble titanium-doped polymer for use as a spectroscopic mix -CI diagnostic. This poster describes the various synthetic Ti- *CI pathways pursued and the properties of the resulting materials. Reasons for the difficulties in creating a soluble titanium polymer will be expored. TYZOR TE Titanocene dichloride Early efforts centered around macromolecular We took advantage of our previous work on the modification. 113 halogenation ot PS to provide a precursor. jllj We began by trying to esterify TYZOR TE with the carboxyiic acid Tho halogenated sites provide the necessary precursor for the following moiety of a methyimethacrylate/methacrylic acid copolymer. synthetic pathway; Unfortunately, the resulting polymer proved to be insoluble. What we polymer-(C HJpJ + BuLJ pdyn^KC^JfLT +Bui really wanted was a way to carboxylate the monodisperse 100K MW t polystyrene (PS) used for mandrol production so that we could execute polymer-(C,HJ:' LT + CO,—— potymer-{C1HJ-COOLT the following reactions. poiymer-(C^J-COOir — poiymer-{C.H4}-COOH+Lr / X anfyd 1HF , . Drawbacks to this pathway Hj-^CH-CHj-Jk »• —CH-CHj-^CH-CHj^- + /PiCH Need for anhydrous conditions. Tfus ban expensive way tomato polystyrene: $ 6 polymer-(CtH4):" LT + H,0— poiymer-(C,H4) p-H -t- UOH C-0 Wurtz coupling causes crossllnMng: I -Lil ? polymer-(C,HJ:"U+polymer-{C,HJp-l " polymer^CJHJ^C^IJ-polymer Excess CO, is necessary to prevent crosslinking: polymer-(CtHJ:' LT + polyrner-(CtHl)-COO:" LP— polynjer-(ClH4)tCO + U,0 It Cannot use methanol to precipitate polymer because of Fischer esterficatlon: k"* Xg H poiymer-(C,H,)-COOH+CH,OH —- polymer-(C,HJ-COOCHJ + H.0 Most of our emphasis was placed on attaching a titanate to a carboxylated polymer is Small molecule reactions were used to test the feasibility of various titanates and pathways O Benzoic add and titanocene di chloride: Carboxylated polystryrene can CftTiCl, + CH,<^H,COOH CpJia(CH,C^4COO) + CftTiCCHjCWXlO), be made by copolymerization. [jig ResuKK Ratio of CpJlCI(p-toluate) to CpJI(p-toiuate), was 65:35 as determined We succeeded in making a selectively carboxylated polystyrene by copolymerizing 4-carboxystyrene with O Reaction with the sodium salt of p-tolulc acid: Cp,TiCl, + NaCCHjQH^COO) •m—p> Cp1TiCl(CHJCtH More small molecule synthesis. Iffl O Blsfacetyiacetonat9)t]tanIum{IV) dilsopradde was synthesized and reacted with tofuic add: THF (acac),Ti(0-<-C,H,), + CH,C,H4COOH -X-> (acac)tTi(CHiC,HtCOO), -CH4 „ , , )!ll Mil Ull j,,, , 1HI 1MI 1111 1211 llll IH Ml „„ Results: A change in color indicates some sort of reaction but the NMR showed the clean substitution did not occur. The NMR indicates that the IR spectrum of copolymer superimposed on that of acetylacetonate is still bonded to the titanium but there is no evidence for the polystyrene with cartJoxylic add peaks Identified. addition of the toluate. The isopropoxide doesnt seem to be bonded to titanium in the product. UAB has pursued a similar routs by making poly(methacryfic acid-co-styrene). O p-toluic acid was added to Triethanolaminetitanium(IV) isopropoxide: CHA , (TEAyntO-f-C.H,) + CH,C,H4COOH -X-> (TEA) n(CH1C,H4COO) Results: Formed polymeric Ti,0, compound. C bis(benzoato)bis(Cp)titanium was synthesized and reacted with benzoic add: CH.C1 CpJIPh.+C.H.COOH —> Cp,TiPh(C,H4COO) Results: Product yields correct NMR results but decomposes upon exposure to light Reaction of carboxylated copolymers with titanocene dichloride yields an insoluble polymer. LH3 Why macromoiecular modification did not work [^j In multistep synthesis, contaminants and side-products build vtyJTHF up in solution from step to step causing crosslinking and loss of reactive sites. For organic chemists a 60-80% conversion to product is considered good. However, it takes only two O O ^ (6 o crosslinks per polymer chain to render the polymer insoluble. c-o C-O I OH Macromolecular modification does not allow us to easily interrupt the process to remove previous reactants and by-products. Furthermore, because the polymer backbone bul also CpjTKC^CsH^COO^ binds the reactive sites together with the polymer bound side reaction products, there is no way to separate the desired It appears that by this route a significant amount of acid product from these by-products. Analysis of this mixture of residues remain unreacted which crosslink to the second products is often difficult to interpret owing to the number of chlorine. A second possibility is that the reaction product is functionalities present. unstable and decomposition products may react to cause crosslinking. UAB has found a stable titanated monomer which has been copolymerized with styrene. Conclusion M[S ABN.50C We believe we've found a way to produce a titanated 0^0 toluene, 2 days copolymer by using a stable titanated monomer which is s subsequently copolymerized with styrene to the desired 0"Ti(0(Pr)a OTi(0 This works because unlike macromolecular modification, there are no unreacted groups to cause crosslinking. We wish to thank Peter Jernakoff of DuPont for his valuable contributions Production of Large Polystyrene Shells by the Osaka Method ILEESE SCHNEIR and BARRY W. MCQUILLAN (6)9) 455-3768 General Atomics San Diego, California 92138-5608 As the lasers used to shoot ICF targets are upgraded and their energy levels increased, it is necessary to produce larger targets to meet the potential of these lasers. Presently microencapsulated shells are produced in the size range of 200 to 1000 /Jm in diameter. Shells in this range have been consistently produced using both single and dual solvent systems of fluorobenzene or a mixture of benzene and 1,2 dichlorobenzene to dissolve the high purity polystyrene. Techniques axe being developed to produce larger polystyrene shells using the Osaka method of microencapsulation. This work seeks to develop high quality poly- styrene shells on the order of 2 to 4 mm. Shells have been produced in the size range 1 to 3 mm. Although producing larger shells (1 to 3 mm) utilizes the same Osaka techniques as those for making smaller shells, variations in the solvent solutions, polymer concentrations, and processing conditions have been necessary. To allow the survival of the larger shells, a. modified solvent system from the production of smziller target quality shells has been implemented. Presently the shells produced are generally clear and fall into the size range of 1 to 3 mm diameter. The wall thicknesses of some of these shells are larger than desired but now that the desired size range has been obtained, work is being done to reduce the wall thicknesses. Characterization techniques to analyze these larger shells have been limited because the size of the shells but efforts are being made to adapt to these new size requirements so that accurate measurements can be made. A presentation of the work done to date will be provided. 2.7 mm o.d. shell made by microencapsulation imrmiHH iMkkiiiaiiMMMHil WHY CONSIDER CONTINUING WITH MICROENCAPSULATION TECHNIQUES? Target quality shells ranging from 300 to 800 |im in diameter have been produced. Microencapsulated shells are very uniform in wall thickness. Shells produced by microencapsulation have very good concentricity. Recently high yields of shells larger than 1mm have been produced. Typical polymershells produced by microencapsulation (300-800 urn) SINGLE POLYSTYRENE SHELL FRINGE PATTERN OF THE SAME SHELL • Produced using Microencapsulation • Fringes look relatively concentric • Solvent system: Benzene + 1,2 Dichloroethane + Ethyiethylketone • Wall Thickness 13.55 jim • 1.0mm In I|ih|H iln I[II i( 50 Ou ZSOyi 500 pm I I I I | I I I I I I I I I I I I FRINGE PATTERN OF THE SAME SHELL • Fringes look relatively concentric • Wall Thickness 13.55 jim 4+ 500 iim f-1'' -f -.-vV^V'V NINTH TARGET FABRICATION SPECIALISTS MEETING Microencapsulation Is A Technique 1 July 6-8,1993 WJS*- For Producing Polymer Spheres. wm An Experimental Design Approach to Microencapsulation • Form a water/organic emulsion. Diana Schroen-Carey W.J. Schafer Associates Livermore, CA 94550 (510) 447-0555 • Disperse in water bath. Form hollow sphere by Work dont (or the US Dcpuuneii of Enctjy. under Coomci DE-AC03-91SFI8601 immiscibility and surface tension. The Recent Experiment 3 Focused on the Solvent System. WJSA- Experimental Design Was Required. WJS3- • Solvent system defines the immiscibility and surface • Systematic analysis of independent variables (factors) tension differences. and dependent variables (responses). • Screening experiments emphasized the importance of • Uses a matrix to evaluate effects and interactions in a the solvent system. minimum of trials. - Large spheres could only be produced with MEK • Results are evaluated using statistical hypothesis based solvent systems. testing and confidence levels. - Vacuoles were controlled by the solvent system. • A multiple step process. • The goal is to produce vacuole free spheres greater - Screening than 1 mm in diameter. - Optimization - Hypothesis Testing Solubility Parameters Were 4 A Mixture Design Simplifies 5 Chosen As the Independent Variables. WSA the Experiment and the Analysis. WSfr • Models based on individual solvents are too limiting. • Solubility parameters u • Solubility parameters give a mathematical basis for for mixtures are ^ i« <,< soiuua:-., -ut.^ calculated from comparing solvents. volume percents of • Total solubility parameter related to physical the components. t properties: energy of vaporization, boil.ng point, 2 surface tension. • Dividing by 8t , solubility ratios sum • Four component system. to 1 and create a - 1R analysis of 0-H stretch H-bonding component, 5h. mixture design. - Dipole moment -> polar component, 8 p • Reduces variables - Polar vs. nonpolar comparison dispersion 2 2 2 2 to 2: 8d /8t , Sp /S[ , component, 8d 2 2 2 2 1 - (8d /8t +8p /8t ). - Total solubility parameter = 8^ = 5 2 + 8 2 + 8 2 d p h • 3 axis system can be visualized. 6 The Empirical Model is Factorial. WJSJi- • Only first order effects and interactions. • Factorial model shows good correlation, no one point has large influence on model. • Predictions are verified. • Large spheres and vacuole free spheres require different conditions: Maximum Diameter Minimum Vacuoles 2 2 2 2 8d /8t = 0.497 8d /8t = 0.496 2 2 2 8p2/8, = 0.286 8p /8t = 0.241 2 2 8h2/8t = 0.218 5h /8t2 = 0.264 • Averaging does not work, too much of the responses are lost. 7 A More Complex Interpretation is Required. WJS3- • Sphere formation is caused by solubility and surface tension differences. • Assume one interface dominates the diameter, the other dominates vacuole formation. • Adjust the internal and exterior water solutions to obtain the proper differences. - Surfactants - Alcohols - Viscosity Agents • Starting from vacuole free spheres, I am increasing the diameter. - Spheres from a sieve cut 250-350 microns are vacuole free. 8 The Solvent Optimization Experiment Was Successful. WJSJi- • Solubility parameters were strong predictors for solvent choice. • A mixture design efficiently covered the experimental area. • The factorial model has been verified. • To obtain the goal, a dual mixture design must follow. - External water - Internal water Six Responses v.s. Solubility Parameter Ratios • Diameter, wall, and stability have similar responses. • Below 0, the blue line, no product will be produced. Vacuoles, non- uniformity, and aspect ratio have similar responses. Responses are flipped. LOCK OF SEM Analysis of Target Contamination Caused by Reaction Tube Etching E.F. Lindsey and S.A. Letts, LLNL A.D. Denton W.J. Schafer Associates Target contamination during plasma polymer deposition creates unacceptable surface finishes of the ablator layer on ICF targets. Plasma polymer is deposited on target surfaces, the bouncer pan, and the walls of the reaction tube simultaneously. The plasma polymer deposited on the reaction tube is ctched into fine particulates by the plasma after glow. The particles adhere to the target and create sites for non-uniform coating growth, ultimately forming surface irregularites. This poster session illustrates plasma polymer etching of the reaction tube walls, particules are generated and the poor target quality surface results.. SEM examination of plasma polymer reaction tube walls and coated surfaces revealed different correlations. The reaction tube surface condition parallels the quality of the coated surface. Increased plasma power dissipation levels leads to reaction tube coating etching, particle generation, and surface contamination occures. SEM Analysis of Target Contamination Caused by Reaction Tube Etching Reaction Tube Exit Etched Polymer on Rough surfaces caused Rough Coating Surface RXN Tube Wall 17.5 watts by contamination during coating Reaction Tube Exit Non-etchd Polymer on Smooth Coaling Surface Smooth surfaces created RXN Tube wall 12.5 watts by contaminate free coating run Poster 13 Session II A LABVIEW DRIVEN, ATOMIC FORCE MICROSCOPE BASED ROTARY PROFILOMETER* C.E. Moore. R.L. McEachern University of California Lawrence Livermore National Laboratory P.O. Box 808, Livennore, CA 94550 ABSTRACT A practical method for characterizing the sphericity of fusion targets has been elusive in past years. Recent advances in commercial atomic force microscopy have resulted in a Stand Alone AIM (SAAFM) that is easily integrated into a sphere mapping instrument The instrument consists of a rotary air-bearing stage with a vacuum chuck and shaft encoder, SAAFM, rotary encoder interface, a Macintosh Dei computer with LabView-based software, and National Instruments data acquisition hardware.. A spherical samp.' J mounted on the vacuum chuck rotates while the AFM tip is in contact with the sample surface. The AFM hardware maintains constant tip deflection by adjusting the length of a piezoelectric element. Changes in height of the sample surface are thus converted to voltage changes, which are digitized by the acquisition hardware/software on the Mac n. The shaft encoder triggers a data acquisition every 0.1°, which allows measurement of spatial frequencies as high as 1800 cycles/revolution. * Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-ENG-48. Unclassified Poster Craig Moore Lawrence Livermore National Lab P.O. Box 808, L-474 Livermore, CA 94550 (510)422-5892 Poster 14 Session II Layering Targets by Microgravity P.B. PARKS and R.L. FAGALY (619) 455-3209 General Atomics San Diego, California. 92138-5608 We show that it is possible to produce thick (> 10 jxm) symmetric liquid layers in hollow targets and in foam targets that axe overfilled with D2 or DT. A sufficiently small gravitational field will permit uniform liquid fuel layers. One method to reduce the effective gravitational field environment is freefall. Another method [l] to counterbalance the gravitational force is to use an applied magnetic field combined with a gradient field to induce a magnetic dipole force (Fm) on the liquid fuel layer. We examine the interaction of surface tension, viscous dissipation, London-van der Waal forces, and the net vertical force [JFm — Fz (in the case of magnetic field assisted microgravity) or F& (the drag force in the case of freefall)] to calculate the dynamics of a liquid fuel layer. [1] A. Honig, private communication. Poster 15 Session II Simplified Fringe Analysis for Wall Thickness Measurements FLB. STEPHENS (619) 455-3863 General Atomics San Diego, California 92138-5608 and M. WITT MAN Univ. of Rochester Laboratory for Laser Energetics Rochester, New York 14853 We have developed an analytic expression to describe the shape of interference fringes produced by a hollow transparent sphere illuminated by monochromatic light. Using this expression, one can calculate the wall thickness of a sphere from a mea- surement of the shape or separation of the fringes relative to the sphere size. It is feasible to calculate the wall thickness to within a few percent*, the limit being the ability to accurately locate the center of the interference fringes. This is a report of work sponsored by the U.S. Department of Energy under Jontract No. DE-AC03-91SF18601. Poster 16 Session II Rapid Shell Evaluation by Rotating Image Interference Fringe Analysis R.B. STEPHENS and M.L. HOPPE (619) 455-3863 General Atomics San Diego, California 92138-5608 We have built a motorized rotating vacuum chuck which can pick a shell off a microscope stage and smoothly rotate it at 1 to 10 rpm. We observe the fringe motion during rotation to find (1) the absolute nonconcentricity (PI defect) and (2) localized wall perturbations (higher order defects). Rotation of the shell allows a more complete examination than allowed by either one view or two orthogonal views; defects which would ordinarily be missed are revealed when they are swept through the fringes. In addition, the speed is such that one's eyes can understand the shell in terms of its three-dimensional structure, rather than just the projected image revealed by static pictures. Estimates of local defect thickness can be made by the magnitude of the fringe fluctuation. Absolute nonconcentricity measurement can be made by stopping the rotation when the direction of the PI vector is in the plane of view, at the point of maximum fringe offset, and then measuring the offset. This can be combined with o.d. and fringe shift measurements to completely characterize the shell in one step. This is a report of work sponsored by the U.S. Department of Energy under Contract No. DE-AC03-91SF18601. GENERAL ATOMICS IMEIIVIIIL WE HAVE FOUND NEW WAYS TO MEASURE ICF CAPSULES CONFINEMENT USING INDEX MATCHING FLUIDS FUSION We use Index matching fluids to measure: IGF TARGET • Composite capsules CHARACTERIZATION USING INDEX — GDP coating thickness & quality MATCHING FLUIDS — 4 n GDP coating uniformity by — Index ot retraction ol GDP coating D.A. STEINUAN • Microencapsulated capsules Presented at Target Fabrication Specialists' Meeting — Foam density Monterey, California — Wall thickness before drying " JULY M, 1993 Work prepared under Department of Energy GENERAL ATOMICS Contract No. DE-AC03-91SF18601 GENERAL ATOMICS cmnbral atomic* A SIMPLE FIXTURE IS THE KEY GDP COATING QUALITY AND THICKNESS ARE MEASURED Coverslips Microsphere Coated Shell in 1.548 Index Matching Fluid 1 Crack in Coating X" Slide or Mirror Index Matching Fluid Optically Rat tit i a ( Hll[llll(llll|llll(llll( 1 -•$» CmtlMtUU. ATOMICS CENBUU ATOMICS STRIATIONS IN THE COATING ARE READILY SEEN WE ROTATE THE CAPSULE TO MEASURE 4 tc GDP UNIFORMITY Striations Caused by interruption [in GDP Coating Run CMNMKAL ATOMICS GENERAi ATOMICS WE USE HIGH-MAG INTERFEROMETRY TO MEASURE THE INDEX OF REFRACTION OF GDP COATINGS THE TECHNIQUE IS VERY SENSITIVE Straight Fringes Through Coating Shell in 1.560 (Shift = 3 fringes) Index ol Refraction Is Index of Refraction Matched Resolved to ±0.001 Index Is Measured at Interferometer Wavelength •*!» CENEBAL ATOMICS > CENEBJU. ATOMICS FOAM DENSITY CAN BE DETERMINED A MATCH CAN BE DETERMINED FROM TWO MEASUREMENTS WITH INDEX MATCHING FLUIDS .u.u u u .1 M fring1 e shift xX Chord length through shell wall = — i f s nwaD - "IMF ^ ..i&fffi1-*1 * i ' * (ijiimuI FMnikdh 1S/0 || K-.7j MOITdly rM«WtwitMlli>M((MLinr. a For a given shell: IMF1 and IMF2 give FS1 and FS2 . . FSIxX FS2 x X For same chord: "wall nIMF1 nwU nIMF2 • 300(1. j_L •I. I..I (FS2xnIUFl) - (FS1xnWF2) Therefore:1 n^ = J^CSHEBAtJtTOMICS ^»CEMERA1 ATOMICS WE USE OUR FIXTURE TO MEASURE DENSITY IS CALCULATED FROM OPTICAL DATA WATER-FILLED MICROENCAPSULATED SHELLS We measured: • CH Index of refraction • Foam wall thickness • Shell fringe shift In air Full density wall thickness Pfoam = PCH x Foam wall thickness Calculated foam density was 41 mg/cc CENEJMU ATOMICS COMPUTERIZATION OF CHARACTERIZATION DEVELOPMENT GOALS R.B. Stephens General Atomics • Minimize « Maximize — Operator tattgua & variabfflty — Fto&Ky — Transcription mim _ Accuracy — Co):idevetopmomti™ — hfcfmaSon retained at — ThoughpU Target Specialist's Meeting Monterey, CA 5 July, 1993 Work Done (or the US Department of Energy, under Contract DE-AC03-91SF18601 GSNSRAL ATOMICS CEMEIUU ATOMICS TASKED TO CHARACTERIZE ICF CAPSULES COMPONENTS FOR COST EFFECTIVE COMPUTERIZATION OF CHARACTERIZATION • Outside diameter & smoothness • VERSATILE MICROSCOPE for complete measurement set • MICROSCOPE LINKED TO COMPUTER makes efficient workstation e Total wall thickness & uniformity • MOSTLY COMMERCIAL COMPONENTS for robust performance • USER FRIENDLY IMAGES for rapid error-free data collection • Coating thickness & uniformity • AUTOMATIC PARAMETER CALCULATION for rapid error-tree data analysis • COMPUTER ARCHIVE for complete data storage > CENEUi ATOMICS GENERAL ATOMICS ALL DIMENSIONAL CHARACTERIZATION POSSIBLE WITH 'LOOSE' SYSTEM TO CONNECT MICROSCOPE WITH COMPUTER SINGLE MICROSCOPE • IMAGE with Microscope Camera • COLLECT DATA w/ "Cut & Paste" • "Transmission" mode for clear view ol edge • TRANSFER wI Frame Grabber • ANALYZE w/ Spread sheet - O.D.to-1% • MEASURE w/ Calibrated Screen e ARCHIVE w/ Computer memory - Diameterto « 1 mm • CALIBRATE w/ Computer Model • Sheared Image while light Interference for wall thickness - \NallWckne3sto<0.1nmlorshelljupto-1 mmOO - Range extender allows wall Bilckness taMpm • Rotation to find worst asymmetry - Finds absolute nonconcattriclty - NCtO-2% - Rotationreveals hig h ortothfctaiessflucluatlon modes • index match to find shell n Y CENERAL ATOMICS CEMSttM Arawes MOSTLY COMMERCIAL COMPONENTS FOR ROBUST PERFORMANCE USER FRIENDLY FOR RAPID ERROR-FREE DATA COLLECTION • Commercial Software lor data collection, transfer, and analysis — National Institute of Haalth 'Image' a '»» l«l WWl IMKI will IHtW ''"»• BMW (D t — McroscA'Euar • Easily viewed & optimized • Custom components for special purpose Screen — mctortzed phase sMflkncb on mfcrescope wrti digital readout • Measure directly on — motorizedrotating vacuu m pickup on rrtciwtBriputoW calibrated screen — Phasateeing progra mto detennlnetalbralloncoetfctenStelrtettewvwtnage j • Cut & Paste Into premade form • Procedures easily modified •j* cENemu AraMics • CENSTTM ATOMICS \UTOMATIC PARAMETER CALCULATION FOR RAPID ERROR-FREE DATA ANALYSIS \ Bilt>W«mi«llwi R«>.ln<« WHITM. B»lr«l(H/«|: TM Mlw»»«»»«IW01: J Hulnl I.D.C: na 7T> Air: tb NA NA NA ' 13 NA NA NA NA NA 14 NA MA NA NA NA ts NA UA NA NA MA 16 NA MA MA MA MA 17 NA MA MA NA NA GENERAL ATOMICS CBHSIMi AIUM1LX COMPUTER ARCHIVE STORES ALL INFORMATION ADDED NOTATION RETAINS SIGNIFICANCE OF PICTURES (100MByte per month) White Light Interference Image of PVA coated shell • Calculation formulas stored with data for future verification • Pictures with notations and commentary — Horoscope — SEM • Short movies — Rotating shel foroveran M) view GENERAL ATOMICS Y CENSIUU ATOMICS SEM IMAGES CAN ALSO BE ANNOTATED AND STORED COMPLETE SYSTEM ACHIEVES OUR GOALS High magnification SEM image of SIC • Minimize • Maximize — Operatorfeflgus & variabfflty — Ftattfy — Transcription emxi — Accuracy — Cost 1 dflvBtopront Una — inioflnaoonretaraj — Throughput > CENEKAL ATOMICS uiEiMinr. PVA CHARACTERIZATION IS NEEDED TO ENSURE HIGH QUALITY TARGETS cunriiiEni(-i« rusion • PVA uniformity and surface finish strongly affects final capsuie parameters — p V A Is the tast uniform layer, tumps in PVA are not smoothed by GDP • Equipment — Microscope; computer; shell manipulator PVA LAYER CHARACTERIZATION • Procedure — Nondestructive method for screening and overall wall analysis — Destructive method for accurate determination ol PVA layer thickness M.LHOPPE and uniformity • Results Presented at Target Fabrication Specialists' Meeting — Discussion ol observed characteristics of GA's PVA coaled Monterey, California polystyrene mandrels JULY 6-4,1933 •I* GENERAL ATOMICS CENEft/U. ATOMICS 4$+CENEBAT ATOMICS EQUIPMENT CONSISTS OF THREE BASIC COMPONENTS TWO METHODS ENSURE HIGH QUALITY COMPOSITE SHELLS • Interference microscope • Shell manlpulator/rotator • Video Imaging/analysis system • Non-destructive evaluation — Determine average thickness ol the PVA layer — Determine total wall non-uniformity (rf tha sheD wail — "Weed-out" shells with localized wall detects • Destructive evaluation — Especially useful when you only have a few shells or the PS mandrel Is of unknown thickness — Accurately determine thickness of the PVA layer on individual sheds — Accurately determine unlfoimlty of the PVA layer on Individual shells CEMElUt ATOMICS CENEIUU ATOMICS NON-DESTRUCTIVE EVALUATION GIVES TOTAL WALL PARAMETERS AND AVERAGE PVA THICKNESS REMOVE PVA FOR INDIVIDUAL LAYER PARAMETERS • Setup equipment and sample — Arrange shells on a grldded glass slide After measuring total wall parameters remove — Setup microscope, shell rotator and computer PVA layer with water > • Mount PVA coated shell on rotator Measure bare mandrel parameters — Measure shell parameters — Discard shells with delectlve coalings ——> — Accurate determination of PS thickness and uniformity • Calculate average coating thickness — Calculate precise thickness ot PVA utilizing — Subtract batch average PS wall fringes from average total wall; PS mandrel; and PVA Index of total wall fringes; index of refraction of PVA then refraction measurements allows the determination ol average PVA thickness GENERAL ATOMICS > GENERAL AT3MICS BEST ESTIMATE OF PVA REFRACTIVE INDEX IS 1.520 PVA LAYER CAN OFFSET MANDREL P1 Wlth/PVA Wlthout/PVA' Wlthout/PVA Worst Orientation Same Orientation Worst Orientation PVA In 1.510 PVA In 1.520 Vacdry50'C35hr Vacdry50'C35hr ABBE MARK IIREFRACTOMETER = 1.517 CENER/U ATOMICS CENETTNI. ATOMICS PVA LAYER CAN ADD TO MANDREL PI PVA DOES NOT IMPROVE OVERALL WALL UNIFORMITY Wlth/PVA WittiOUl/PVA Results of Destructively Analyzed PVA Coated Shells Avg. PSWil:U|im — -4W-PS (^m) Avg. PVA Wilt IS |im NX AWall = 3.4 m AWall = Unm 4 S ShtHHumbci Shell Is In the same orientation Delta Walls Wall (max) -Wall(mln) CENEPAL ATOMICS CENEBAL ATOMICS PVA TENDS TO HAVE LOCALIZED DEFECTS GREAT LOOKING PVA COATED SHELLS DO EXIST ••$» GENERAL ATOMICS CONCLUSIONS PVA HAS HIGH VARIABILITY IN UNIFORMITY • PVA index ol retraction determined by two methods — Index of PVA has been determined to be 1.520 • PVA can add to or subtract from mandrel Awal) — PI ol PVA Is aligned with PI ol mandrel — PI ol PVA Is opposed to P1 ol mandrel • PVA generally lowers overall wall uniformity — Random orientation of less unllorm PVA coating with respect tomandet • PVA can have 'easy to miss" localized defects — Use of shell rotator and Interference microscope can minimize this possibility It necessary -S|» GENERAL ATOMICS AWALL REQUIREMENT DETERMINES YIELD AND SELECTION PROCEDURE -> PVA Limits Final Capsule Uniformity <- ShtUNumbw Delta Walls Wall (max) -Wall(mln) A DESTRUCTIVE TECHNIQUE FOR MEASURING THE FILL OF A FUEL CONTAINER* • M.D. Saculla and S.A. Letts University of California Lawrence Livermore National Laboratory P.O. Box 808, Livermore, CA 94550 ABSTRACT Measurements involving the amount of fuel and diagnostic gas inside a capsule are difficult to conduct. Early techniques involved breaking a sample capsule in an oil and measuring the dimensions of the bubble produced to determine the amount of fuel present. This technique was not accurate due to the difficulty of making the measurement and the fact that many times the broken capsule produce more than one bubble. A few years ago, an instrument was constructed that observes the freezing of the D2 fuel inside a capsule during a cryogenic cycling. Noting when the freezing occurred produced a dewpoint temperature which relates the amount of fuel present. While this technique is accurate in determining the amount of D2 present, it does not give measure to mixed D2/H2 fuels or diagnostic gasses. Two techniques will be presented in this presentation. D2 is measured by breaking the capsule in a known small volume, measuring the rise in pressure and using Boyle's ideal gas law to calculate fill D2/H2 fills and diagnostic gasses are measured by breaking the sphere inside a volume, then slowly bleeding the gas into a mass- spectrometer. Calibrations are made to the mass-spectrometer by measuring sample gasses at various known pressures in a separate chamber. * Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-ENG-48. Unclassified Oral Michael D. Saculla Lawrence Livermore National Lab P.O. Box 808, L-474 Livermore, CA 94550 (510)422-5891 HIGH RESOLUTION OPTICAL MEASUREMENTS OF BETA-LAYERING IN CYLINDRICAL GEOMETRIES J. K. Hoffer, Los Alamos National Laboratory John D. Simpson and Jane B. Gibson, General Atomics Evan R. Mapoles, Lawrence Livermore National Laboratory ABSTRACT Optical measurements made with a high resolution CCD video camera show that the solid DT layer formed by the "beta-layering" process in an isothermal cylindrical bore of 2000 |im diameter may meet the strict criteria for layer thickness uniformity required by implosion considerations (~1% of the average layer thickness). Measurements have been previously reported on an experiment in which a 73 |im thick solid layer was formed. Although the solid DT layer on the bore equilibrated with the expected rate constant of -30 minutes, the layers on the optical windows were not optically smooth after more than 16 hours, leading to slight optical aberrations in the final image. We present new measurements taken in the same geometry where much longer time for final equilibration was allowed. LA-CP-93-146 High Resolution Optical Measurements TimfcraUlon M 1Uwn DT L«yw SwteM Rntah of ..,.1.1 . 1 Beta-Layering • 1 .! ; ? in •+i! ! ll i i r i : 1 • ' : i i .. I" i i Cylindrical Geometries ! < i I- i jt- M i» ]; \ • f • -1 • i* -ll-l".- i.. •i i'.T Junes K. Hoficx, IAHL •IT r John D. Simpson and Jane B. Cfbttm, CA I i t jllj i - i ' ! Evan K. Mapoles, LLNl tjl! • i • •i •:V i: 1 l i 6 T 1- . | .. , 2 i . i i a i. 1 . 1 1 r -!•! i i mi- i! .Li ... 1 wUh looof belptrom Larry R, Foreman, LANL FFT of 125am IXT I jiyier & Empty Cell Cell with 12Sum DT Solid Layer ...... ^ .ij^d't . t ^ .• • - '• r.j map i M « VT\ Sam Layer Cell Inner Bore DT Surface Ocftct Mode Number :o -3 i NEW POLYMER TARGET-SHELL PROPERTIES AND CHARACTERIZATIONS* * A. Honig, X. Wei, Q. Fan, N. Alexander and N. Palmer Physics Dept., Syracuse Univ., Syracuse, NY 13244 ABSTRACT * A method for characterizing ICF target shells is presented, based on measurement of the gas released from a single shell into a small volume. It utilizes cryogenic permeation systems developed in connection with our work on ICF targets containing nuclear spin- polarized D. Permeation rates for polystyrene and parylene-coated-polystyrene shells are measured at temperatures from 350K down to 180K. Burst or implosion pressure can be ^ determined over a full temperature range down to 20K. Shell temperature is calculated from its gas leakage rate, calibrated by permeation measurements over the temperature range. Lag of shell temperature compared with sample-chamber temperature during warming of the latter is attributed to the weakness of the thermal link provided by both radiative heat transfer and free molecular conduction with small accommodation ® coefficients for helium and deuterium gas at the structure to which the shell is conductively linked, or at the surface of a conductively isolated shell. Quantification of this lag can provide a measure of atomic scale roughness of the shell outer surface. Also presented are reversible pre-rupture leakage phenomena for polystyrene and parylene- coated-polystyrene shells. Fig. 1. Apparatus for permeation and burst pressure characterization of single polymer shells. High pressure gas is delivered to sample chamber either from gas cylinders or from cryocondenser. Shell inside sample chamber is filled to pressure p0(Ts), with Ts usually at room temperature, by incremental permeations. Temperature, Tc, of sample chamber, is then lowered by immersion in bath (77K coefficient for the material, Kp(Ts), and the shell geometry. P' (= P - bt) is the background corrected pressure. Permeation constants are obtained in a constant Ts mode. Variable Ts experiments, consisting of slowly warming a shell initially at 77K by means of the weak thermal link to the sample chamber walls which £ * Work supported by DOE through LLNL Contract f/B 15736 are at held at high temperature, give shell burst and NLUF Grant #DE-PS03-91SF18892. pressures. A conceptually similar apparatus Target shells provided by R. Q. Gram and H. Kim of LLE, exists for experiments down to 4K. University of Rochester Fig. 2. PERMEATION OF SPHERICAL ia CL 3.0 1 " T 1 SHELL OF RADIUS r. W = wall thickness; Ts = shell temperature. Initial shell pressure = p0(Ts). a, 2.5 e a O O o o 0 o ° Shell is inside sample chamber whose initial O) L. 2.0 pressure is P = 0. (P « p for more than 10 time 3 cnin constants since shell volume v« sample 01 1.5 u chamber + Baratron volume, V). R is gas cu Gas T(K) T( S) 1.0 constant. Kp is permeation coefficient, with c / He 296 109 o u a- a He 273 200 - activation temperature a. 10 _ i <0 1 1 1 CO 1 1 1 7 !• Pt(Ts)=p0{Ts)e (Shellpressure) nJ 2.0 - b l CL 2. P =P-bt (Background corrected) 1.5 <11 x u 3. P =P/(\-e ). 3 in in Gas T(K) r(s) a) t- He 296 109 _ Wr PL, 0.5 -i¥ ° 4. X = He 273 200 3 KPRTS 0.0 f r I I 200 400 600 800 1 > Time ( sec. ) 5. Kp(T) = Kp(293)e Fig. 4. Outgassing of shell E, to determine its permeation time-constant, a) P vs t; b) P' vs t. rf T^TM- T(293) r^^ 6. 1(T) = —=—e Parylene-coated-polystyrene shell, r=265nm, Wp0|y = 5jxm, Wpary=2|im, lies in a screened aluminum cage. 5.0 (B ° He 273 57.6 1- (0 I 1 1 1 CP I 1 1 1 <0 2.5 Q. cu b 2.0 I a. QJ 1.5 - U / 3 Gas T(K) r(«) W w 1.0 a) o He 295 35.9 i_ 0.5 Q. ° He 273 57.6 " 0.0 T i 1 1 1 0.01 50 100 150 200 250 1000 2000 3000 4000 Time ( sec. ) Time ( sec. ) Fig. 3. Outgassing measurement of shell C, for determination of its permeation time-constant, a) P vs t; b) P' vs t. Polystyrene shell, r = 266 nm, W = 6 |im, Fig. 5. Semi-logarithmic plot of (Pf'-P'WPf'-Pj') vs is loose in a screened aluminum cage. Similar results time, vhose slopes yield the time-constants for 2 are obtained with a shell epoxied to a copper stalk. gases at several temperatures for shell E. 2 3.0 333K 250K 200K 1CQK 10 Ou ID L. 3 Uiv> O 0.0 0.003 0.004 0.005 0.006 10 15 20 1/T Time (min.) Fig. 8. P' vs t for shell E filled to four different pressures. Sample-chamber temperature profile is the same as described in caption of Fig. 7. Initial delay in pressure rise is during radiation-induced warm-up Fig. 6. Semi-logarithmic plot of permeability constant, period. As temperature rises, outgassing commcnccs. Kp, vs reciprocal temperature. The slopes give a, the Faster relative out-gassing for higher fill-pressures activation temperature, for the shells and gases used. shows pressure dependence of gas heat conduction. Fig. 9. RADIATIVE AND GAS MOLECULAR a. 0 4 - CONDUCTION WARMING OF a£ 0.3 - CONDUCTIVELY ISOLATED SHELL. "i w 0.2 - (D £ 0.1 - 4 Qs{RAD) = esGAs{Tc :-T*), Qs(GAS) = asA0As^(Tc - TS)P. A 100 {- as is the accommodation coefficient and n. S (0 0 AQ is the free molecular conductivity: 3.4 x 10"4 w/cm2.°C.Pa for deuterium, 00 0 5 10 15 20 25 30 2.3 x 10"4 w/cm2.°C.Pa for helium. Time (min.) Fig. 7. P' and sample-chamber time profiles for shell E When shell is conductively linked to a filled to 1 atm helium, a) P' vs t; b) sample-chamber conductively isolated (from sample chamber) temperature vs t. At t = 0, liquid N2 bath is removed support-structure, such as a stalk, or cage, from sample-chamber, and at t = 4.0 min, sample subscripts s apply to support-structure rather chamber is immersed in water at T = 70°C. than shell. a) Si 01 (0 3 a. cton a) t-H 01 IX w. G O ut Fig. 10. P vs t for polystyrene shell #4, cpoxied on Time (min.) copper stalk, r = 288 nm, W = 10 jim. Shell is filled to Fig. 12. a) P vs t; b) Deduced temperature of shell E 6 atm with helium and with deuterium gas. Sample- vs t, from Eq. 3 of Fig. 11. Temperature "plateau" in chamber temperature profile is described in caption of time interval near 8 min is believed due to start of Fig. 7. Shell filled with D outgasses earlier than one 2 cooling of shell via incipient gas conduction to cage, filled with helium because of higher background countering direct radiative warming of shell from outgassing rate of D and larger accommodation 2 walls of sample chamber. coefficient on copper stalk of D2. in Fig. 11. SHELL TEMPERATURE MEASURE- a MENT FROM SHELL OUTGASSING RATE QJ L. 1. Rate of outgassing depends on x(T ) and 3 s inw OJ u pressure difference, Pj~ P{. CL c o L. dF Prpi v a CQ P'jrp; Time (min.) 3. T = Fig. 13. P vs t for a series of shell E (paiylene coated Av dt - i) polystyrene) fillings at higher pressures. Numbers alongside curves identify the order in which measurements were taken. Sample-chamber V and V are defined in Fig. 2. From the temperature profile is described in caption of Fig. 7 instantaneous x values, T is inferred from the s for all measurements in the series. Reversible damage permeability determinations of Fig. o and Eq. 4 (pre-nipture) is incurred in run #3, at a shell pressure of Fig. 2. of 18 atm, calculated from the Ts of the shell at the break point, and the gas leakage up to that point. It is noteworthy that the shell behaves entirely normally when refilled later to only 12 atm (fill #5). 4. I Fig. 15. SUMMARY 1.-Simple single shell Kp measurements. If shell (0 is uniform and of known material, gives wall Ou thickness. V L, 2.-Temperature measurement of conductively to3 in isolated shell, or shell thermally-linked to a V u conductively isolated ?talk. a. a o u 3.-Simple burst pressure measurements as <3 function of shell temperature. u (0 CD 4.-New "pre-rupture" shell phenomena. 5 10 15 20 5.-Emissivity and accommodation coefficient measurements of shell or supporting stalk. Time ( min. ) 6.-Use of measured accommodation coefficient at shell surface as a determinant of surface Fig. 14. P vs t for a series of helium gas fillings at higher pressures, for stalk-mounted polystyrene shell roughness on an atomic scale. #3, r = 262 um, W = 9 nm. Numbers alongside curves identify the order in which measurements were taken. 7.-Possibility of spatially profiling shell's surface Samplc-chambcr temperature profile is described in roughness, thereby "tuning" the accommodation caption of Fig. 7 for all measurements in the series coefficient for a selected thermal gradient along except for #1, where at t = 4.0 min, the sample- the shell when there is uniform internal heat chamber temperature was raised to 40°C instead of generation in the shell and rarefied (molecular the usual 70°C. The resultant slower radiative conduction heat transfer regime) isothermal warming in # 1 produced a normal outgassing, despite the high fill pressure. The faster warming rale in #2 helium gas is the coolant. resulted in "pre-rupture", similar to that in the previous figure, at a calculated pressure of 28 atm, with Ts at 235K. It is seen that the damage is not total, since the shell retains gas in subsequent cycles (#3 to #5). One notes that due to the gas law and the outgassing of a shell under these temperature-rise conditions, the internal shell pressure, p, rises from its starting value at 77K of 335T0 over a considerable range, reaches a maximum, and then falls. If during this process the pressure exceeds p(burst), given by 2WJ(TS)/ r , where J(TS) is the temperature- dependent tensile strength, the shell explodes. Following an initial fill to 48 atmospheres, we did explode shell C at a pressure of 29 atmospheres, with 6 2 Ts at 220K. This gives a J(220K) of 61 X 10 N/m , to be compared with the room temperature value, 48 X 106 N/m2. This is consistent with the increase of J in other polymers with decreasing temperature. This method is convenient for measuring polymer tensile strength vs temperature, avoiding laborious experiments with incremental pressure increases for a measurement at a single temperature. 5 nm- Acknowledgements Micro-Catorimctcry as a Method to Measure Fuel Mass in ICF Capsules Evan Mapoles Marita Spragge Dr. James Sater Jon Ruppe W. J. Schafer Associates, Inc. Livermore, CA 94550 Steve Mance (510) 447-0555 Ed Pierce Presented at the Ninth Target Fabrication Specialists Meeting July 6-8, 1993 Monterey, CA Work done for the US Department of Energy, under Contract DE-AC03-91SF18601 mass- WJSZ- How Do You Measure the Amount of Gas Inside a Why Do We Expect Calorimetry to be a Useful Technique? Shell After Doing a Permeation Fill? • It is well known that a gas to liquid or solid phase transition occurs at some temperature below the critical point. • Current Methods Disadvantage Critical Point (Kelvin) Triple Point (Kelvin) - GEVF Destructive test. nH2 33.19 13.96 - Fabry-Perot interferometry Requires optical access. HD 35.91 16.60 nD2 38.34 18.73 - Dewpoint method Requires optical access. • This phase transition can be related to tha gas density (fill pressure). • Calorimetry is a classical technique to study phase transitions. • Plus calorimetry: does not require optical access. is not a destructive technique. can be done many times to the same shell. • Problem We are looking at a small signal and must design our experiment carefully. mm- Theory of Ciilorinietry Constant Volume Constant Pressure Saturated System Cv cp Cs • dQ = C dT • Cs = mi c's + mg c9s + L dmg/dT In T Figure 2.7. The change of entropy with in T along the saturation curve (full line), along one isobary.{dashed line), and along three iscchores (dotted lines), the second of which passes through the ' critical point P As P • \ /fv T>Te liquid-solid T T liquid-solid vapor" ~ c solid . vapor-solid-- solid T< 71 vapor-solid V V WJS& wm- AC Calorimetry K*«t Cl^Milj *t ClWtMtM HmI Capacity at Sftapk Supli *ND C*I«t1b«Ui - iitUrpdaUd laU wttb m(m I-" W* • Sample -> Cs heat capacity of the entire calorimeter. Ts sample temperature. TawprHui* flUMa) G conductance of weak thermal link to surroundings. mass- HUSH- AC Calorimetry Experimental Setup • Basic Idea • Our thoughts on calorimetry lead us to some basic requirements for - Apply an AC voltage to the sample heater at a frequency (to/2). the design of our apparatus. T )AC - Do phase sensitive detection of Ts at to. ( S is proportional to - The signal due to the sample should be a large as possible in 1/C comparison to the addenda. The calorimeter parts need to be • Assume made of materials with small heat capacity and need to be small. The sample, heater, and thermometer remain in thermal equilibrium. - The heat conductance to the bath must be well characterized and The bath has infinite heat capacity. controlled. Parameters such as C and G are essentially constant over the induced We want a good vacuum to limit gas cooling. temperature oscillations. We want to limit radiative cooling. • Model We choose the conductance of our thermal link as required by the model. The thermal link is provided by the wires to the heater and dQs/dt = Cs dT/dt = Power In - Power Out thermometer. Power In = Joule heating from sample heater - We must work at cryogenic temperatures in the 20 to 35K range. Power Out = G (T-To) • Solution TAC -> G / (to C) TNIFCPI as to aets larae. Tnr. is the time ripn^ndent lorimcter Subassembly Cryogenic Insert ' VVJS/5 WJSA WJS*- mm- Progress to Date Sample Data • We are getting preliminary data. • We have an number for G, the conductance of our weak link. • We have a number for the heat capacity of the calorimeter. • • Our error bars are large because we have done a very crude analysis of the data. A more careful analysis can only help. • The data is less than a factor of 2 different from calculated values. This is reassuring. " " CHI Time 200 m3ec/0Iv 90-10 Decay time = 160 mSec" 248Q -> 13.25 K 147ft -> 14.25 K Max voltage = 7.44 mV G = I.4XIO-«W/K : Min voltage = 4.4 mV t= C/G = 160 mS/ln 9 = 72 mS C = 1011J / K • MiUSLI- Future Plans • Increase the S/N. Implement Lock-In detection of our signal. • Detect the transition. • Increase automation of the data taking and analysis process. • The ultimate goal is to build an instrument capable of doing the calorimetric measurement in a production environment. VG COVER DT ICE 2 Assembly for DT in 6 mm Quartz Shell Experiments m Roughness of DT Ice Evan R. Mapoles Presented tc: Group Leader Ninth Target Fabrication Cryogenics Specialists Meeting Monterey, CA l| UwTBnctlhtnnore II HrttfMj Ubenloqr July 6-8.1993 Empty and DT Filled Quartz Shell Evolution of DT Beta Layer in a 15 mm Spherical Sapphire Shall .li t= 14400 sec ts 19200 sec t= 37200 sec ww> 2 LANL 75ymand 125pm DT Layers ua Image Analysis Technique ja XngK (ndUiu) 75 Mm 125pm Surface Roughness of 125 pm DT and Empty Cell [ig Comparison of Power Spectra .119 2000pjii2 _ lxio"1- s 3 1x10" 1x10" 1x10 1x10" -n T— 0.001 0.01 1000 10 100 Frequency (l/microm) Node Number Power Spectra Models .115 • Luyer Power Spectra . g{l) = (0.187JP*"0-°87' _ 10. ft • ww-1^ P2D{1)- -4n d jPl D{Jn1+P)dn W+T)7Il 0.1 o.ot 0.001 0.0001 S 10. 50. 100. 500. 1000. Uod* Number Other cell geometries for studying (^-layering have better optical access than spheres .113 Cylinder with Internal Heater [ig LANL Copper Cylinder LLNL Hemlshell Fill Un* •-2.00 mm. Glass Cylinder v.'', 2.00 nun Copptr Block RUUnt SappMra Window f Sipphlr* Hamlthtll Glass Window Image of Glass Cylinder M Analysis of Glass Cylinder .113 Surface Profile Power Spectrum o* 330* 10 100 1000 180* Mod* Number Further Work m • Imaging ol OT in hemlshells at LANL • DTalLLNL • Develop better layering methods for D, and H, • Bettor Image analysis algorithms • Ray tracing • Interferometry In shells A Small Volume Tritium Fill System M.A. Salazar, P.L. Gobby, H. Bush, J.K. Hoffer and L.R. Foreman Materials Science and Technology Division Los Alamos National Laboratory Los Alamos, NM 87545 USA ABSTRACT Environmental concerns demand lhat all tritium releases be minimized. In particular an experiment recently fielded at Los Alamos National Laboratory required a four cubic millimeter volume to be dynamically filled to a pressure of 7MPa, while keeping the total tritium content (and potential release) below 20 Ci (1 Ci = 3.7 x lO^O Bq.). We describe the system which was designed and built for this purpose, complete with a low volume fiber optic monitor and pressure transducers. SPECIFICATIONS ENVIRONMENT and SAFETY i Small masse* of trlllum correspond la relatively • Environmental concern* demand that all high activity. The relatively short half-life ofl2J tritium rdwn he minimized. year* and low nun result In a specific activity of a An experiment recently fielded A Lot Alimoj neatly 104 CVg. National Labor ory required remote dynamic i Tritium ts normally a gas and must thus bp filling of a four cubic millimeter volume to a contained In hydrogen leak-proof containers. pressure of 7MPa, while keepinfllhelot.il I A* an Isotope of hydrogen, II can exchange with the tritium content (and potential release) below20 hydrogen In water. Trlllated water.as it iscalled. is CL the most biologically dangerous form of tritium. • The system was designed and built fortius I Flammahlllty of tritium requires that all safety purpose,complete with a low volume fiber procedures normally associated with hydrogen must optic monitor and prmwc transducer*. also be followed. Lo" A1 r. m n • Low Alomon SMALL VOLUME TRITIUM FILL SYSTEM TRITIUM RESERVOIR 85mm~3 in Ihe transducer filling and closed valve Lu* Ala mot Los Alemos REDUCED VOLUME AUTOCLAVE REDUCED VOLUME AUTOCLAVE ENGINEERS 4071 VALVE ENGINEERS 4075 DOUBLE VALVE Stem * C«» Path L.o m Aim Lot Alimoi Page 1 PRECISE SENSORS PRESSURE REDUCED VOLUME PRECISE TRANSDUCER SENSORS PRESSURE TRANSDUCER c. CMA . ^ Slrain Gaufr ^ Mr ^ DoJy Plu * Los Alamos v ^ Los Alamos RESERVOIR VOLUME DETERMINATION FILL SYSTEM LN OPERATION > Pressure Transducer • Determination ofewperlmental vokimr by eipanslonof hrihimfrorn^MlibriUd mrrvoir. Manual Vnlve Graduated • The helium resrrvolrw*s replaced wHhtheD2-T2-Xe \ rrtrrvoit Cylinder ^ V-r • tVKhMVrvduinJngclosed but AOV1 ind A0V2 open, the lyilrm wuigjb) evacuated. • Tube • AOV1 And AOV2 were (hen doted. • MV was then opened «nd the stem adjusted to the _ J previously determined position. —— Beaker • Wtthpenonnel t*fely Temovsd from the jrta, AOV1 was of thenopeneJ remotely, filling the e*prrimrntal volume to Water the desiredr pressure. Los, Alomoi Loo Alpmoo r • T i i SUMMARY • By aHeringcomniercialromponents.areliahtt and safe fillsystem has been designed and fabricated to deliver tritium containing gases lo pressures as high as 7MT*a. • Though M included two prvsstir* transducers, three valves, a tritium monitor and over four metersof tubing,the total volume was less than 275 mm3. • The tritium monitor proved to give a useful signal for tritium pressures as high as 10 MFa. • In operation, the fill system performed flawlessly. Ua Alomoo Page 1 ICF TS&T 93.1 proceedings 18 240 Solid Hydrogen Surface Studies 13 Gilbert Collin* Evan Mapoles Walt Unit** Warran Giedt A study ol non-1rUiu:»d >olld hydrogen layer* • ^ ICTCi jnyniCT W« have 3 dltterent techniques to grow hydrogen layers: Solidifying through the liquid phase 1.RnarMSubllm*tlon sometimes leaves a meniscus residue 2. Low Tanpirriuri D«po«ldonfrom ttio Oa o nil 3. Cooling Through «m Triple Polnl that Is difficult to anneal away. ^ hyttogan got Ml IMM / N. H with 18 mW/cm*, T = 13.3k 777731 t ocyoottf odd Ip | 10 crull thfmal gradl *nt thcouph Icq SolldHled '''Ciilff///"'^ «"> SolldHled through . through liquid D«» ph«M w&^m phaae •HurodwoiHonlromoMBhM. I low tomporMur* CH „ AI.O, Bo, and MgP oubttMta •IM K r«dl«llon thlald I oom >ompoc«ft»o window Nairn hot moMtd tio looUnnno «nd 1 lUix Y» h—iw po^.*f. mmimwimummmma ICF TS&T 93.1 proceedings 6 7 We use a phase mapping Interferometer to measure the 2 dimensional surface roughness gj The phase measurement technique was Invented by Btuning et. al |J l(x,y, D) '»,*», co»2k0 * a, iln2Mi j («.y.» d.y.2) («.y.J) «(,,y) 3 23 ill' ?' t u ©tDtGhk 1.1 l-Z 1-3 " / liP ? 1 i 0 Th * Interf erogram Intensity, l(i,y,D), Is Fourier transformed along the reference phase uls, 0, to obtain the Fourier coelflclenla a , M FSB and thus the solid hydrogen density profile • w(x,y) - tan -'(a^yk Resolution tm - 2 jim A*AY - S |im Temporal evolution of the RMS while depositing H , Example phaaa map used tor quantitative analysis ol hydrog en layers. ^ by reverse sublimation near the triple point. y 100 Jim thick D, layer at 18.4 K and with 5 mW/cm* heat flux through the layer v H,«iBtd13K Ybun) IhMlmln) Samples grown at hlghsr temperatures deposit more rapidly due to the larger vapor pressure, snneal more quickly due to too o higher surface mobility, and result In smoother eurf aces. o V ICF TS&T 93.1 proceedings 10 11 The RMS surface roughness, o, Scaling properties ot surface roughness: iq follows a simple self afflne relation: M Surface profilM can be modflad through disc rat* or continuum models «uch as a modified Langevln j L° when lor the power law P(f)-1/fT we find Y*2a+1 |h(l))-f-Xh(x,t.i ) ° Moreover p • a/(2-a) + 12 13 At low temperatures solid hydrogen Plasma polymer coatings from will form crystals Steve Letts and Evelyn Fearon are self-atflne |g • At low temperature the surface fret energy Is minimized V crystals have flat facete 100 • Only low lnd»x orientations are stable Low temperature High temperature m 10 tcz 1E+6 0.01 1 100 Frequency (cm»-1) Thickness (|un) So for a particular sst of coating conditions ws can predict O and P(l) for any capsule radius and plastlothlckneee. ICF TS&T 93.1 proceedings 14 15 At temperatures below T/TTP~.87 the solid conforms to the isotherm with flat crystal Growing crystals below T/TTP~.87 on MgF, forces building blocks. faceted crystal growth. This shows the roughening temperature, TR, IS between 0.90>77TTP>.87 In D2. D, 16.4 K, 0420 mW/ctn' Di 17.4 K, 1.69 mW/cm' D, 16.4 K, 0i2 mW/cm' D, 17.4 K, 042 mW/em' Higher temperature reduces surface roughness for pure components. Subtracting the background allows us to extract an activation energy for the motion of molecules on the surface. .0 0.8 r o a 200 |imDt Q • • 10 ofH^-expfSigiCT) e cm .0064 W/cm' £ < Si 0.6 1 \ 85 1: n W c \I Is ||0.4. i cc o 3 s in Si 0.01 8 a (Dj) - exp(491 K/T) K no !> 0.001 0.01 0.1 0.001 16 17.5 19 1.05 1.1 1.15 1.2 Frequency (1/(im) Temperature (K) Triple Point Temperature/Temperature T for power spectra - 1/f : lower ? Implies Ihe RMS Increaeee Activation energies for molecules In the bulk are mora slowty with Increasing length and thlcknsss 1 E,(H,)=1S0, E,(DJ)=270, implying o ~ 1/D \ ICF TS&T 93.1 proceedings 18 19 A large heat (lux through the hydrogen film forces Increasing the heat flux through the solid hydrogen a smoother gas solid Interface. M layer also reduces the surface roughness. y hut flux H, »t 12.0 K • E II III J 3 D, at 18.4 K o Hj surface RTU>P(T2) -T^TJavg) o E r T(avg) in S cc T(avg) 0.0001 0.001 0.01 0.1 Heat Flux (W/cm*2) *ln D-T than are many Ions through which to couplt power into the gas and solid. 20 21 Smooth layers produced by low temperature deposition ars unstable when Increasing the temperature. g "Thistransformation otthelayer results In an Increase In surface roughness of over a factor ol 5 (3.3 « J.<211|im). g Hers we ramp the temperature IK/mln from 5 to 8 K. This transformation occurs over several minutes at a temperature nsarS K If this the result of an amorphous phase of hydrogen?' ' SK 8 K V » ¥ iisvj^ BBSS ICF TS&T 93.1 proceedings 22 Conclusion: by choosing a path through and position In phase space we can form hydrogen films with the necessary uniformity for the NIF. Much work Is required for Implementation of these techniques. {g 02 18 K with about .002W/cm*2 o(after convergence) - 5 nm Frequency (1/|im) B3BHW Compensation of the Lens Effects of Thick Cryogenic IQbJective | Layers Using an Interferometric Imaging System There are several requirements of a cryogenic-target interferometer r®- A cryogenic-target Interferometer with the following properties is desirable: - good phase sensitivity to high-order fuel-layer nonunlformltles - suitable for a wide range of capsule/fuel-layer dimensions - simple, stable, and amenable to computerized phase control (phase-shifting interferometry) - compact enough to be adapted to In-sltu fuel-layer characterization Ninth Target Fabrication Specialists Meeting M. D. Wittman Naval Post Graduation School University of Rochester Monterey, CA Laboratory for Laser Energetics 5-8 July 1993 Interferometry is sensitive to a small nonconcentricity Thick DT layers may be best characterized in the solid DT layer at infrared wavelengths ya_*t ujaW- Outer diameter S1120 |im f/6 optics Outer diameter = 1120 Jim Shell wall thickness =10 ftm Wavelength 514 nm Shell wall thickness = 10 (tm Solid DT thickness =100 nm Solid DT thickness = 100 fim f/6 optics X = 0.51 fim X = 1.0(im X = 2.0 fim TlflM The lens effects of thick cryogenic layers are reduced The transmitted wavefront consists of both with convergent-beam illumination a spherical and an aberrated component \\ Focal lengths of targets of experimental The spherical and aberrated components of the interest have been calculated transmitted wavefront have been calculated UB JUB- LLB* PS capsule wall thickness = 10 pm Outalds PS capsule wall thickness = 10 pm diameter (um) 0 0 Outside Spherical abberatlon Xj (jim) diameter j/ 700 900 1100 -10 700 900 1100 -50 -15 _> . i 0 20 40 60 80 100 20 40 GO 80 100 Fuel-layer thickness (urn) Fuel-layer thickness (nm) 9 • The beamsplitter assembly provides several functions The cryogenic target interferometer is basically a Mach-Zehnder configuration CCD array Beamsplitter il l 3 4 \ / Variable voltage source Interferograms using plane-wave and convergent-beam [Conclusion] illumination have been produced The lens effects of thick cryogenic layers —— — yg m are reduced with convergent-beam illumination UB -jfr .uBW • Only the spherical aberration component remains In the wavelront for greater phase sensitivity. • The Illumlnatlon-beam's focus can be adjusted to compensate for a wide range of capsule/fuel-layer dimensions. • Stretching the optical fiber provides phase-shifting capabilities without translating optical components. • Short-coherence-length light reduces noise from spurious reflections. Plane-wave Convergent-beam Illumination Illumination Til 18 T1120 Study of Thermal Layering for Millimeter Size Cryogenic ICF Targets by K. Kim, E.M. Simpson, and J. Zhang Fusion Technology and Charged Particle Research Laboratory University of Illinois at Urbana-Champaign and T.P. Bernat and J. Sanchez Lawrence Livermore National Laboratory Presented at The Ninth Target Fabrication Specialists Meeting Monterey, California July 6-8,1993 Work supported by Lawrence Livermore National Laboratory and the National Center for Supercomputing Applications at the University of Illinois THERMAL LAYERING TECHNIQUE EVOLUTION OF THEORETICAL WORK RELEVANT TO THERMAL LAYERING TECHNIQUE Vertically Imposes thermal gradient across the A Consideration of equilibrium liquid layer target so that gravity-Induced fuel sagging (which configuration Inside a target under isothermal wlHresult In fuel layer nonunlformlty) may be conditions: exactly counterbalanced. Mok, Kim, and Bernat, Phys. Fluids 22.1227 (1985). References: • L. Mok, K. Kim, T.P. Bernat, and D.H. Darling «t Calculation of liquid sagging time, which J. Vac. Scl. Technol. £1> 897 (1983). requires calculation ot bubble velocity at the target center (I.e., r s 0) as a function ot • K. Kim and L. Mok, UCRL Report temperature, liquid layer thickness (t), bubble UCRL-15647, SIC 41B0405 (1984). radius (Rs), etc. • K. Kim, L. Mok, M.J. Erlenborn, and qonrluslon: Fast Isothermal Freezing T.P. Bernat technique Is Inappropriate for thick liquid- J. Vac, Scl. Techno!. 1195 (1985). layer formation since fuel freezing time Is longer than fuel sagging time. • K. Kim and D.L. Krahn J. Appl. Phys. fil 2729 (1987). K. Kim, Fusion Technol. & 357 (1984). • V. Varadaralan, K. Kim, and T.P. Bernat J. Vac. Sci. Technol. ££, 2750 (1987). ft Calculation ot bubble velocity, u (or nonuniform temperature field: U = f (Tave, t, Rs, VT, Thermal Properties, Mok, Kim, Bernat, and Darling, J. Vac. Scl. Technol. AL 897 (1983). For multiple-component case, analytical solution The analytical solution gives a closed-form for u s 0 al r s o Is not possible. Therefore, expression for the thermal gradient at the target numerical solution of navier-stokes equation must surface that will produce a uniform liquid layer. be employed. An analytical solution for a stationary bubble at One must account (or: the target center (i.e., the solution for u = 0 at r = 0) Is possible for a single-component case, and • Component separation, and the gives the thermal gradient needed to form a resulting surface tension gradient uniform liquid layer as a function of: • Particle diffusion • Shell Diameter • Shell Thickness References: • Shell Thermal Properties • Liquid Layer Thickness • K. Kim and L. Mok, UCRL Report • Layer Thermal Properties UCRL-15647, SIC 4160405 (1984). • Bubble Thermal Properties • Gravitational Acceleration • V. Varadaraian, K. Kim, and T.P. Bernat: J. Vac. Scl. Technol. £5,2750 (1987) and AS. 1876 (1988). • E. M. Simpson, K. Kim, and T.P. Bernat, J. Vac. Scl. Technol. filfi, 1288 (1992). NUMERICAL MODEL • Numerically solves the equations of continuity, momentum, energy, mass diffusion-convection, and conservation ol the Individual Isotoplc species In various regions of the target and target exterior, with proper boundary conditions and a few simplifying assumption". • Performs various sell-consistency checks. • Finds the thermal gradient which keeps a liquid fuel layer concentric with tha target shell and balances the net force on the vapor bubble Inside the target. Iioltormi In haSum aic.Mnga en /iaeaua/y Is a tut a unifcyn Iquid layar fcuMa • D| Urgat. Tna largit Mi a 200-tim damaiar SOS. a U^pm wil, a m aim rsom-lamparalura U pniui and an anraga Iwynm 0*24 K. Al dti lampamufa, ma iqud D? layai iKduiau * 4.21 ^m. Tameatwuta tcioit vapof-Iqua Wartaea. and acrou lha Urgat. Motility to cram • uniform t<;uo layef « a ?00->im mmataf Ot taigal al an avaraga Jaigat lamparatura of 24 K. o.oo o.2o o.4o oeo o.so 1.00 NondmansionaJ Radial Cutanea Nondmanaional Radal Qnra (») (c) (a) Flow Cald Inaida tha ioo-iini (Samaiar Dj tarsal at an avanea tampimura of 24 K. (b) Vtloary profila along noruonul eana'-ina In rapor. (c) Valoaly poMa along honionul can>«r-ln« In Iquid. •OMSOT/1 o!3o 0.20 00 0 (0 0 to I.CO •TOO Toi T02 To3 Nondmanuyxal fUdul Oiltanc* NoncSmanaional padal (61 w 1 i m k,uW UoiM/mi in halium a COMPARISON BETWEEN THEORIES AND EXPERIMENT tf D2 Target: 200-nm diameter 8.35-jun wall thickness 133 atm (III pressure *H-D Target: 600-nm diameter 6.25-iini wall thickness 75 stm (lit pressure laatharm* In twlium atchanga gat nocaiaajy to cfmala ft urttofm Iquld tayof Insist a binary O-T tarsal. Tha targai haa a (OOiun damattr SOS, a iMitm wall, a 75 atm room-tamptratura Ail praimra and an cv«fag« lamparafcjrv of 22 K Al ins lamptraluia. IK tqud O-T layar miemuw to B.93 |urv H-OTugM OaTupM •o&fimdUflwter JOO-jun damrtv sas^wiwll itttimwtt 7SatmnUptM«ur« 133 Mim II pt%uut% / n • t • / • I,J / % * ••• t / 7 •• 0 / / % 1 s / ~ 4 1 • / J 1 •m i 1 \ •• • y /• • | I \ \ .-• y J.* - PrvsanlModtf I. tlMM CM.U* 9 bparlmmt'KlfnMtL |M IWI I^IBO* ktMM cmj*m _ -0- |*«ma| ItoM • llnuy Uitun |M rwl WMf>( i,« • w rm.1— . «• fMK muux -i- Pr*Mnt Madtl • Ternary Ulnun T 19 20 21 32 23 24 25 26 37 28 29 90 31 32 33 34 it n ti I! Av«rag« Ta/?«t Ttmporatur* (K) Av*rag«Ts/g*1 Itmpwturo (K) ANALYTICAL MODELS 4 Model 1: - Includes tntertaclal tension gradient effect. - Derives an equation for the thermal gradient that Is required for formation of a uniform liquid fuel layer. 250C0 * Model II: 20 40 60 60 100 Liquid Layer Thickness (|im) - Includes combined effect of Interfaclal tension gradient and mass transfer. - Derives an quation for the thermal gradient that Is required for formation of a uniform Model 1 and Model 2 predictions of the thermal liquid fuel layer. gradient across the target necessary to create a uniform liquid layer in the 1 mm diameter D2 target at an average temperature of 20K. The thermal gradient is plotted as a function of liquid layer thickness. SUMMARY OF ANALYTICAL CALCULATION SUMMARY OF CALCULATIONS ON ON CRYOGENIC D2 FOAM TARGET CRYOGENIC HD FOAM TARGET 5-Reglon Calculation liquid Tgp • m 380.36 |im b»400(ini c mSOO |irn Liquid laytr Uilckneis • 8.64 pm Sponge thlcknass • B0 |im a • 390.33 |im Shall thickness • 10 pm b « 400 jim Main !arg«t Umperatura: Tm « 20 K c • 500 |im Lifting force on the bubble: F • 0.348383 <10-3 dyne Liquid layer thickness * 8.67 (im Weight of the bubble: W • 0 J46105 x 10-J dyne Sponge thlckneas • 100 pm Thermal conductivity of liquid Hi • 1.11 < 104 erg/cni.i>K Mean largat tamperiuira: Tm » 20 K Thermal conductivity ol liquid Dj • us x 10* erg/cnvt SUMMARY € We have assessed the feasibility of employing thermal layering technique lor tabrication of thick liquid layers In mm-slze targets, with the conclusion that, In Its current approaches of Implementation, TLT will not work. 4 As a solution, we have proposed an alternative approach^ employing a foam shell target, and the analysis indicates that it should work. H Sacks and Darling: Nuclear Fusion 2L 447 (1987) Cryogenic liquid layer goals m Liquid H2 D2 layers in Large Capsules Support liquid layers in large capsules - I to 3 mm diameter Support layer thickness of 50 to 200 Mm Achieve surface finishes of better than 0.1% of thickness Obtain layer symmetry of better than 1% of thickness Jorge J. Sanchez Presented to: Target Science & Technology Ninth Target Fabrication Specialists Meeting, IMvanlly o< CaMwnta Monterrey, CA n July 6-8,1993 AJ.S.ftov.soan j-J-iAMnon Introduction: Liquid Layer overview m. Thermal gradient generation techniques m • For a one component fluid i.e. D2: Helium gas column between differentially cooled heat sinks I. A negative (cold on top) thermal gradient drives both a simple evaporation - recondensaiion process and a surface tension gradient which work together to cancel Differentiallycooledcapsulewithheliumgasjets-mostappropriatefordirect the gravity induced layer sag. drive tajgets • A multi-component fluid like H-D or D-T spawns an additional process: Direct gradient imposition by heating capsule with an intensity graded laser beam 1. A positive (hot on top) themial gradient causes preferential evaporation of the lower vapor pressure component (H) from the top of the capsule, generating a concentration gradient Direct heating of the capsule wall by absorptionof U V/VIS light of the proper 2. The positive (higher on top) surface tension gradient generated by the concentration wavelength gradient opposes gravity and levitates the liquid layer. Helium gas jets and UV/VIS healing hybrid to improve cooling capacity for larger capsules with high fuel fills or for direct drive applications J.J ».n»v.«m> J.J.9 ffevMOV Helium gas column between differentially coolcd heat sinks is Differentially cooled capsule with lielium gas jets [l^S • Requirements: > Requirements: 1 High capacity cooling power 1 High capacity cooling power 2 Dual laminar He gas jets 2 Static conductive gas medium 3 Accurate gas jet alignment 3 No convection > Advantages: Advantages: 1 Applicable to direct drive capsules 1 Excellent temperature control 2 High cooling capacity due to convective 2 Very stable and repeatable cooling action • Disadvantages: • Disadvantages: 1 High power dissipation 1 Unstable temperature gradient, difficult 2 Stringent geometry requirements to control (LLRE experience) 3 Difficult to implement in target chamber 2 May need vety large gas flows upon environment scaling for large capsules with high fills 4 Limited gradient capability for useful 3 Possible large debris generator from heat sink spacing hardware too close to capsule J.J. J. FUMOKU RKMM3 Direct gradient imposition by heating capsule with an IMH Direct heating of the capsule wall by absorption of UV/VIS intensity graded laser beam light of the proper wavelength • Requirements: • Requirements: I Direct optical access to capsule 1 High power highly collimated filtered UV/VIS light source or low power laser • Advantages: for fiber coupling 1 Excellent temperature control if used • Advantages: with s static cooling gas in enclosure 2 Low cooling requirement (for static gas 1 Excellent temperature control if used with a static cooling gas in enclosure case) ' 2 Low cooling requirement (for static gas • Disadvantages: case) 3 No direct optica] access required 1 Needs line of sight to capsule • Disadvantages: 2 Sophisticated beam optics necessary for proper gradient control 1 Accurate liber alignment may be 3 Inefficient use of laser power required 4 Impractical with high absorption or reflective capsule coalings 2 Untested concept J.ILHHIWH lJ l'v< worn Ilclium gas jets & UV/VIS heating hybrid to improve cooling IUM capacity for larger capsules with high fuel (ills [vj^ Optical system schematic and data collection layout m Monitor Computer tJTT— > Requirements: itif 1 UV/VIS light source or excimer laser 2 High capacity cooling power In • Advantages: 1 Applicable to direct drive capsules 2 High cooling capacity 3 No direct optical access required ' Disadvantages: 1 Accurate fiber and gas jet alignment 2 Laige gas flows may be needed 3 Unstable temperature gradient (may improve if gas jets have equal temp.) 4 Possible large debris generator from hardware too dose to capsule J.XH(WMH4 Liquid layer test cell with target assembly and component parts. Detail of capsule after installation. Measurement technique E • Computer aided photometric analysis centered perforation in top gradient plate will accomodate a 1 mm optical fiber for testing UV beating technique 1. Densilometric analysis of 14 bit resolution Images 2. Geometric measurement of high spatial resolution images (10001 pixels) 3. Spectral analysts of layer thickness defects • Assess the capability of Interferometric techniques for thick layer analysis 1. Holographic interferometry 2. Con focal scanning fiber optic interferometer JLJ.I.RKMM1 j j a. rm moms The forma (ion of a meniscus on the fill line opening effectively nig l.uycr thick IICSS culculution front liquid meniscus volume ||IH closes (lie opening forming u contiguous surface Uba approxiinullon [U3 In a fill tube with liquid, the meniscus that forms effectively In a fill lube without liquid, the closes the fill tube opening opening causes the liquid layer to allowing the layer to behave as ir be offset away from the fill line there was no fill tube 8,- ^.O^-c®) , 2 oa H 2& »• wO t£ ( 1 meniscus height as % dia. J4-I.IW «2M3 J.JLRX DM Liquid layer test of a -2.2 mm shell with fill tube attached, andjlljl a calculated liquid volume for a layer thickness of ~17fim Simple! 31 Simple'51 Simple » 76 Average Icfnpcnturc • 21.0 K Avenge Icmfvraiurc » 21.0 K Avenge UTufx-i^urc * 21.2 K GradkM - -0.38 K/cra CnatM •9.6K/cn CmicM > IBJ Kfcni Time • 10.07 miaula ttme - 25.2 minula Time » 37 li minutes Recent experimental results in thermal gradient supported ill • liquid layers Dynamic gradient generation technique • The camera is started squiring streaks at -3ftec. New dynamic technique has been used to extend the gradient generating capacity of the cryostat. • The (op plate temperature Is increased very fast by applying high power to the top better until the We are now able to generate gradients up to 30° K/cm Tor maximum gradient is reached short periods or time. • Data b aqulrtd for tbe duration ot the ramp Thick oblate layers > SOpi have been levitated using this technique and although there are large low order mode defects, the layers appear stable. J.J.LKKnM Glass capsule with a 40^m layer on top. Calculated till for a 111 • Streak record of a vertical section of a capsule with -50 nm on nm uniform layer is 50|i. at 22.7 K. Thermal gradient is 30.6 K/cm-^g top. Calculated fill for a uniform layer is 50n- at 18 K. jv!=g 30 40 Seconds j i % n«w nni Glass capsule with a 10pm layer on top. Calculated fill for a IIIM Glass capsule with a ~50pm layer on top. Calculated nil for a IIIB uniform layer is 30fi at 19.5 K. Thermal gradient is 21.3 K/cm.^jg uniform layer is 50p at 21.3 K. Thermal grudlent Is 30.3 K/cm.^j| J. J. I. Rn W3U93 J J- I Rrr «y»3 Sol'd layering attempt with a 50:50 H2D2 filled capsule at an ig Present cryostat configuration distorts the gradient isotherms average temperature of 14 Kelvin with a 2 Kelvin gradient [^g causing cold spots at the capsule's equator Calculated temperature d istribution for the capsule clamped 111 • between two heat sinks Is similar to model with gradient at QQ LS3 Requirements: Test support of thick (100 pm) layers with thermal gradient Advantages: Direct measure of power required Minimum power dissipation Maximum possible gradient Disadvantages: Proper thermal isotherms for a centered spherically symmetric layer may be difficult to obtain Improper isotherms may cause early instability development SJ inK«m laaxMH) UUKB The Objective of This Study Is to Develop Better WJS.1- »«/•/#«" Insight to Guide the Experimental Program A Simple Model of the Thermal Layering of Cryogenic D Fuel 2 • To gain a clear physical understanding of the dominant physics of thermal layering of D2 with and without foams. • To develop a model that can be run quickly and interactively on a Michael J. Monsler PC using MATHCAD. W. J. Schafer Associates, Inc. Livermore, CA 94550 (510) 447-0555 • To use an integral formulation of the nonlinear equations of motion that is not limited to describing thin layers. • To match the published data and then develop simple scaling relations to describe thicker layers (10-100 |im) in larger targets Presented at the (21 mm). Ninth Target Fabrication Specialists Meeting July 6-8,1993 To generalize the model to treat the more difficult multicomponent Monterey, CA problem (HD and DT) eventually. •>TTSf»c Mj 7/OUAM Wort done for QIC US Department ol Eocijy. uoict Cotuici DE-AC03-91SF18601 iTFSeac.uar/uuju.4 am* iQM Theory and Experiment Agree That a Thin Liquid D2 Layer MMUOr?* Can be Formed by Impressing a Negative Thermal Gradient 0.0 •100 TARGET WO .|C"0»(lf* 011 T[. •io.tj. i.» ticw^m 111 »!• MU MflKK -13.0 . -.0.0 - •»o. -ao.o - 3 •ao.o. L la.o To.o 27.0 i4.o ».o n o 30 0 Jt.o l* AVERAGE tARGET TEmpCRAIURE " I Fig. 2 Linear thermal jradienn outtidc tbe helium region required 10 fa uniform liquid iiytn tnjiCt a IC&pm-diim D, t>i|et. Tampartfua dMa on ha batwto cf Iqiid hydrooan Mop* Mda Tharmal/Mjoad bahavlor ctf IqtMfflbdu a a of hydrOQan a afkarlciMral dracty drhmfaarlal cwHnan m Won laigal laolopaa Inalda a apfiarlcaj Inartlal conflnamant (ualon largal ICNaianriLMok V.Vtaadaia|>AanJK.Nm T.Banvt Felon Tedwiogy Lifccntey hafenTadmclogy Laboratory lawanca Uvermora Ufcaratyof toon Nafonal Laboratory napaitNa.Mt UajttM J.te.W.TadvA»M JK^Auguat mr What Are the Dominant Physics Principles of wm- UURJL The Approach Is to Use an Integral Formulation of the Thermal Layering of D ? 2 the Fluid and Heat Flow Equations The liquid layer on top is heavier than vapor and must be levitated. Use temperature-dependent properties of D2 and shell. The negative temperature gradient causes vaporization at the bottom of Guess the velocity profiles and temperature distributions. the bubble and condensation at the top, pumping the fluid upward. Determine the critical mass flow rate such that mass, momentum, and energy are conserved and the flowfield is steady-state. The heavier liquid returns downward along the inside of the shell causing a downward viscous shear force on the bubble and on the shell wall. Calculate the corresponding heat flows and temperature drops through the shell, liquid, and vapor. The rate of change of momentum of the upward flowing vapor exerts an Calculate the total temperature difference across the microsphere upward force on the liquid layer. required to levitate a given layer thickness. Calculate the linear temperature gradient imposed across a helium cell There is a critical mass flow rate for which the body forces, shear forces, that will lead to the desired temperature difference across the shell. and momentum transfer all balance, and the flow field is steady. Scale to other shell sizes and layer thicknesses. TF Sf»c Ulfl tm MJM-4 Ull The Simplest Control Volume Surprisingly Contains The Mass and Force Balances Follow Both the yquld and Vapor phaseS WJSJl- Directly From the Control Volume glass or plastic shell hemispherical control volume/surface (dashed) m-P^-pM^-*.2] liquid return flow upward flow downward flow upward vapor flow of vapor of liquid This viewpoint allows us to ignore the details of phase change and surface tension at the bubble interface 1 i^-Rf) +|*P R?lg - - m( u,) 2 9 V v. Balance the forces on the control surface and on the mass inside the control volume with the net rate of change of momentum through the downward weight of liquid and upward shear rate of change of control surface vapor in hemispherical CV lorco on liquid momentum In vertical by tha wall direction 2F, = FF, + F v dVol+ z = gravity shear = Jt{ P f u-dA . cv . cs The Layer Thickness, Flow Velocities, and WJSJl- Thin D2 Layers are Viscous-Dominated, Critical Mass Flow Rate Vary with Temperature WJSSr Thick Layers are Thrust-Dominated ' P(i|| = 133 atm V-K-B Capsule 1 P/(W-"ib) (Rf-Rf)h Lay v Wdowia, mlcrona Bubble r*Juj. micnxi, p_ Momentum transfer to upper layer Shear force on upper layer 8 V- R2 "1 r • F is a kind of cryo-layering Reynolds number • Thin layers (h<30nm) are viscous-shear dominated. The vaporization is just the pump, requiring only a small AT. Vapor and Iquid vebdtiei. nVa Mail IkM rata, ktfi aoM • Thick layers (h>60nm) are momentum transfer dominated. The layer is levitated by the thrust of the vapor, which takes a large AT. i> as as 30 at X TT See 7/8) ULI ITF 3p«L r/W HM-* tmt MOM The Balance Between Vaporization and Recirculation Is The Temperature Differences Across the Shell Layers M*J The temperature differences across the vapor bubble (v). the Squid layer (Q. and the shed (s) are: V2 V-K-B Capsule Q-m b (T>f+H, -rr h T 0d ) g iTs(T)JtSSSCa. ATI( T) ' > °"! kgs(T)KRo* kl(T)*-Rs ATs(25) - 0.022 ATI{25) - 0.018 ATv(2S) • 5.636*10 ' This is (fie powar flowing upward in tha The temperature difference across the entire diameter o( the mkroshiU Is vapor (solid red lino), the powar (lowing down- ward h tha liquid (dotted blue), and the ATtot(T) := 2-4Te(T) + 2 ATI{ T) f ATv(T) ATtot(2S) - 0.08 net powar (dashed green) (lowing upward through tha capsule in response to (ha Impressed ui p negative temperature gradient. Units ara watts. Ofctv(T) Note that a maximum In tha nat powar transmitted OM(T) through the capsula occurs as the temperature OJXT] Increases and the liquid layer thins. ana(T) at IB 20 33 X 33 The Temperature Gradient Across the Helium Cell Vf The Calculated Temperature Gradient Has About WJS.1 I Is also Determined by an Integral Relation vr The Right Shape and Location of Maximum We underestimate the gradient required to layer the D2 fuel The temperature field is of the form by 15%, but we've used no fudge factors whatsoever. > O, TARGET SOO HJCRMtU ojurf ita f.JS alOWaCICft IUU. At r=a lU ftto flu MfW At r-»=> T(r.Q)-T0+|gjjco5e AU the heat flowing upward through the midplane. through both the target and helium, flows out the top plate. Take limit as Rg/a-.®. CI n. Obtain §-110.0. II.0 30.0 21.0 24.0 2t.O ».0 ».0 32.0 34.8 il Z» plant nathaatSow h»al tow through AVERAGE TARGET TEMPERATURE 'II through sphara heBum of mldplana M^L^li) Tic. t Lineir (hernul jtidienuouuide the helium rei'ion required lolorw uniform liquid layer* iroidc • 200>.m-diirn D, target. •< TF Spac. I*a »®J WU CtTFSeae.lag 7IUUjM-< The Temperature Difference Required to Layer Direct Thermal Layering of D2 Is WJS*- WJS*- D2 IS a Very Strong Function of Layer Thickness Impractical for 100 micron Layers Plastic Shell Thickness 10nm Absoluts temperature difference Outer Radius 500jim across tha shall diamatar, Kelvin Layer Thickness lOO^m Nat heal How through the shell, waits Deuterium Temperatura gradanti In Ktan. *t ik.. Temperature difference across shell, Kelvin iTIOfll.R) OdcHh.B) jjl-rocfT) attar h, 2 n) Qdol|h.:n) iO"JTa«(T) Ac r.n call SO 7S 100 SO 75 loo ln A r 1993 yjfj^^lm P " * Recommended a Hybrid D2 Target with * 5-10(xm Thermal-Layered Liquid and 90nm Foam WJS/l- shot) R0.500 Thickness of plastic shell 10jim Foam thickness 90nm Diameter 1 mm Oj liquid Free D2 layer thickness 5-1 Onm in loam The majority of liquid is immobilized in the foam Fill Pressure 750 atm lies layer, olD, The free liquid layer is thin and can be layered with a small and practically achievable CsJ Total temperature dfferenes across Total temperature dlferenes shall as a function ol layer thickness as a function ol tomperauro 1 1 1 1 The layering of thin layers has already been demonstrated, although not in large shells The majority of the temperature drop is due to heat transfer through the liquid/foam region • The surface quality should not be dependent 0i 1 1 1 1 s e 7 • s to on foam cell size or foam surface quality io'kt) t, YT SE*C. U*» irou*M fl TF Sp*C Ma 7/S3 UJU-* y\fJ§Ar Conclusions 1. A new analytical model of thermal-gradient layering of D2 has been created to understand the dominant physics and derive scaling relations. 2. The model fits data for thin layers (3 fim) in small shells (200 urn diameter) to within 15%. 3. The model confirms that 100 urn layers of free D2 will require impractically large thermal gradients across the shell (> 200 K /1 mm). 4. A hybrid thermally-layered foam target is proposed which could have the advantages of both approaches and might provide excellent inner liquid surfaces independent of the foam pore size. 5. A 1 mm diameter hybrid target with 90 urn foam and a.5-10 nm free D2 layer should symmetrize with AT s 5 Kelvin across the shell. &Nertc ^ONf^ce I nAa-i^c- l^iTMLLy A MIXTU%£ ap frt A P««ee OF pei/Tenn/-* tr.ITtv* P<*»«.5 8y irkAs/iry IAI THE Qerron at Hvvwa-ef liaTare FR-ACTI OVATION The. ihiti-"} lAjrtaioK. 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Ctfit-J -t— A T^TAC (JF At»wr£p Ofj tyuA/CAi£A<_ ; THE*/ Nf.itep TO A«ice Cf/lfl-Cf ASJ£/"i6ir ~ LtloSTAT Tail 0 O-rO I &radiw>/tJ 3 o,b> VJATti rar f^FLtij WH4T cm*/ bc €*nerei> tuHtf dtwDt^JCD /fvPsotf-c*' T !i{f».r. ."'tJ pn.oTo"?. Its' E)t«/ifi£ •' tece*) euvs-PiMe^f/o^L pa««u OF socio R,oor\ ft <•' .W! 11 MYOR^tA/ /tT /5-fr [ £0% <*-Hz p^J ^cai/lSlTIU*/ T|/16 3 m~urts 1.0 cm D 1.5-f i-iy.eti UllK. ax = y r P/Xgt S/lE » 1.3 mm VfTUf^f HF.ATEi ram. 0fJt-Vl^B^ffd^Ai. PrufftLC of Tuere^S "V Us+rc*. A/atle X~10 Look AT Five 0.7 f e* * 0.75 ev TeAiPe«jir£yn.e Ar fS"K, 116+JAL <5 evHAtJCtv By FACT**. OF 2 o o.~7 thick U\yte. tff hY08.oA-t*» ue TIM65 T«£ CMS$-StLTieAJ OF UlACCt*. f^/nfLi. NwtifeAK. Sfw De^Sirr R£lATive T0 pROT«/v* U>aT6K , x--»•-n-J^. tlAJ V6"firr : Dc/fen. : ."Jv II 12. Tftf-r'ft JcMiTivir/ RCL/)Tlve Ttf J ViHar^i tlMC SeASfirtviry a. at AA^t/C fato/wce /J pn»roitv 0 f\t, a PAoec To AifiAjuftt PEr/^iry iSaroPti Yhi'. UTC«tMfit$f foi.it UnTt fOK StfrHAL trJ t. wo e£ p w rofl JL. F/ttfin HfiP.iv OftVFusffP Te. I Hi { f£c 2.T. irt'TttefMlik. TO Lew Tf.*rf.*-ATI/HI IAiahp. 10 JEC. Al«/LT»Pfy AU TH6JE f/»croR$ TdfrCTHen F«K ild+JAl } ?Hoieaev MABiuTttf 6as$i> o*> wre*. •' OF ONZ- PRO FILL '• fi.esOU/TidtJ : ^ - ^ft/M. J Hoi St ?tUTO»f loo K UlAitt*. \~U) eA/t-P//i£A/Ji#*-Ai. fROFltf PIKWJ (f K \too fa*TeA>s it If K "bo 0H/TenrKfS "iff TWO- IsiA+e ULTtture $r*Ti*c netoLi/TioH ii vertn"<"£t> fly $pw- $f/A/ HtlAIATID/J t>o»r»«/j irK K i A A*/ A Low-Mass Mounting Method for Cryogenic Targets, Roger Q. Gram, Daniel S. Brennan, and Stephen G. Noyes, Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, NY 14623-1299; Roy A. Mangano and Robert L. Fagaly, General Atomics, 3550 General Atomics Court, San Diego, CA 92121-1194 A plastic shell target for the OMEGA Upgrade is supported by three topero;! carbon fibers in a configuration compatible with DT permeation and cryogenic cob'i.i-;;, The carbon fibers are smoothly tapered over their 3 mm to 5 mm ler.gth by exposure to aii oxygen plasma. The target is bonded to the fibers with a thin, uniform"cozing of jVarylene instead of using glue spots of indeterminate mass. While th<= fi&v m^cle ., as small as 1 Jim at the tip, fiber dimensions are constrained by the required i^ffnesr afi * strength of the mount. For various fiber dimensions, vibrational frequencies iuui mechanical deflections are measured and computed. Survivability of the mount dursrij thermal cycling and mechanical shock is demonstrated. 2 This work was supported by the U.S. Department of Energy Office of Inertia! Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460, Ihe University or Rochester, and the New York Stale Energy Research and Development Authority. The support of DOE docs not constitute an endorsement by DOE of the views expressed in this article. The work performed by General Atomics was supported by U.S. Department of Energy Office of Inertia! Confinement Fusion under Contract No. DE-AC03 -91S F18601. A Low-Mass Mounting Method The target mount consists of three tapered carbon fibers for Cryogenic Targets UB un LLB ' • The carbon fibers are tapered In an oxygen plasma to tip diameters as small as 1 pm. R. Q. Gram, D. S. Brennan, and S. G. Noyes • The fibers are parallel, 3 to 5 mm In length. University of Rochester • The fibers make end contact to the shell, Laboratory for Laser Energetics not tangential contact. • The polymer shell is bonded to the fibers R. A. Mangano and R. L. Fagaly with a thin, uniform coating of parylene. General Atomics Ninth Target Fabrication Specialists Meeting Monterey, CA 6-8 July 1993 Material for a three-fiber mount should have stiffness, low density, and low Z There is a conflicting set of requirements on the target mount 1000 <0 800 a a Carbon fiber • Minimization of mass, density, and atomic ?ltch based number near the target 3 600 \ 3 • Mechanical stability in the laser focus •a Boron (motion < 5 pm) o E Carbon fiber. x • Compatibility with DT permeation (A 400 PAN bared a • O) c Beryllium • Survivability for cryogenic cooling 3 Polyethylene, 0 > 200 ultradrawn • Non-obstruction of the 60 OMEGA beams x * PclyamTvi Quartz « fiber 0.5 1.0 1.5 2.0 2.5 Density (g/cm3) TIISS | Target support | The tapered fiber mount has less mass near the Target support mass is minimized target than mounts previously used _UH_ Support materials are For a single-fiber mount, minimized by using submicron spider web Is strengthened by spider-web silk libers. parylene coatings. Threa spider webs (tangential contact) Three tapered carbon fibers, 1-|ini tip diameter 20 40 60 80 100 120 140 1—400 pm—| 1-100 finH x, Distance from shell (pm) The lowest frequency vibrational mode is found by The stiffness of a mount depends vibrating the base laterally on how the fibers are arranged o o o o OH resonance Resonance 43 Hz Relative stiffness Rigid joint 16 Flexible joint 7 2.4 TMJI Without being moved, the shell is joined to the fibers The shell is placed on the fibers with with a thin, uniform coating of parylene a crescent-shaped holder ua -m>. Microscope Witness o Ch plate Shell Alpha source Positioner To Carbon Parylene fibers vacuum <- system monomer run There are potential drawbacks Several carbon fiber mounts to the tapered fiber mounts UB have been tested cryogenically LUX1 -US. uua * Survivability lor realistic handling steps is • Mounts cooled to 10°K In a windowed cryostat presently unknown. showed no distortion. High thermal conductivity of some carbon The mounts survived mechanical shocks fibers could affect the DT layering process. at low temperature. mi) poly (n-mathyl styrene) a-melliyl alyrana