LA-5250-PR PROGRESS REPORT “wiiu!i!l%%iiiir COPY @ ● Progress Report I LASL Controlled Thermonuclear Research Program for a 12-Month period Ending December 1972 10sb a Iamos scientific laboratory of the University of California LOS ALAMOS, NEW MEXICO 87544 /\ UNITED STATES ATOMIC ENERGY COMMISSION CONTRACT W-7406 -ENG. 36 This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contrac- tors, subcontractors, or their employees, makes any warranty, express or im- plied, or assumes any legal liability or responsibility for the accuracy, com- pleteness or usefulness of any information, apparatus, product or process dis- closed, or represents that its use would not infringe privately owned rights. This report presents the status of the IJKL Controlled Thermonuclear Research program. Previous annual status reports in this series, all unclas- sified, are: LA-4351-MS LA-4888-PR IA-4585-MS Printed in the United States of America. Available from National Technical Information Service U. S. Department of Commerce 5285 Port Royal Road L Springfield, Virginia 22151” Price: Printed Copy !$5.45; Microfiche $0.95 . LA-5250-PR PROGRESS REPORT UC-20 ISSUED: June 1973 10 Iamos scientific laboratory of the University of California LOS ALAMOS, NEW MEXICO 87544 Progress Report LASL Controlled Thermonuclear Research Program for a 12-Month Period Ending December 1972 —. ‘--T- ~mpiled by F. L. Ribe i s. m CONTENTS I. Introduction . .. O. O.. .. O.. .O . ..O1 11. Theta-PinchProgram . 3 A. Sumrnaryof8-PinchActivities . ...3 B. Scyllac 5-Meter Toroidal Sector Experiment . 4 c. LinearScyllac . .. .. ,27 D. FeedbackExperimentsonScyllaIV . ...34 E. ScyllacTorus . .. ... .. .. 37 F. PlasmaDiagnosticMeasurements . 37 G. Diagnostic Development.. ...41 H. Scy~acComputerandDataAcquisition . .43 I. ScyllacFeedbackSystem . ...45 J. Electronics Development.. .............46 111. Z-PinchProgram . .. .. .. .. .. .. .47 A. Summary . ., . ...47 B. The Shock-Heated Toroidal Z-Pinch Experiment . 48 c. MHDStabilityAnalysis . .. 54 D. COzHolography . , . .60 E. TransferCapacitorCkcuit. ...61 F. DetonatorCrowbarSwitch. ...62 G. AnA1l-MetalToroidalDischargeTube . 62 IV. Experimental Plasma Physics Group Program . 65 A. Summary . ...65 B. Anomalous Absorption of Large Amptimde Elecwomagnetic Waves Nearthe Electron Plasma Frequency . ...65 V. Implosion-Heating Experiment . ...73 A. Introduction and General Requirements . 73 B. Preionization . ...74 c. The Search fora Pulse Generator System . 74 D. Diagnostics . ...76 E. Chronology . ...76 F. High-VoltageT ethnology. .. -....77 Appendix V-A. Calculations of the Performances of Various High-Voltage Generators . ...77 Appendix V-B. Marx Generators . ...80 Appendix V<. Electrolytic Resistom . ..81 Appendix V-D. High-Voltage Gasket Tests . 82 ● Appendix V-E. The Electrical Strength of Water-Insulator Interfaces . ...83 ✎ ... ffl . VI. Theoretical Physics Program. 84 A. Summi.ry . 84 B. Summary of the Scyllac-Related TheorY . 84 . c. Summary of Toroidal Z-Pinch TheorY . 91 D. Summary of Vlasov-Theory Work. 91 E. Toroidal Belt Pinch Equflibtia. 92 “ F. Perspective on Various Axisymmetric Toroidal Devices . 93 G. Stability of Diffuse Toroidal Z-P~ch Equilibria . 96 H. Numerical Simulation with a Continuous Distribution of Initial Particle Positions. 97 L AXIEmpirical Closure Relation for the Vlasov Moment Equations . 98 J. Linear Stability Analysis of High# Plasmas . 98 K. Comparison of Numerical Simulation Algorithms . 99 VII. Sherwood Engineering . 101 A. Scyllac Support . .. 101 B. Z-Pinch Support . 104 c. Implosion-Heating Experiment.. 106 VIILFusion Technolotw-. 107 A. Introduction . -.......107 B. Time History of the Thermonuclear Cycle . 107 c. Reversible Magnetic Energy Transfer and Storage (RETS) . 107 D. staging . ...107 E. Numerical Studies of the D-T Phma Bum . 108 F. Flushing and Refueling of a Pulsed Thermonuclear Reactor by Means ofa Neutral Gas Layer.. ...108 G. Federal Council on Science and Technology (FCST) Energy Study . .......109 H. Neutronic Analyses of the RTPR. ...110 L The LASL/CTR Nuclear Data Library . - . 116 J. Integral Data Testing with the Wyman Experiment . 116 K. Radiation Damage to Metals in 0-Pinch Reactors . , . 118 L. Electrical Insulator Studies . ...120 IX. Magnetic Energy Transfer mdStor~e . ...124 Publications . ...127 b . iv . I. INTRODUCTION (F. L. Ribe) Thw year has seen the completion of experiments on both the 5-m toroidal ScyUac sector and the 5-m linear ScyUac experiment. The SC@C system is now being converted to ita final toroidal configuration. Results on the sector and on the Scylla-IV-3 feedback experiment indicated the necessity of increas- ing the Scyllac major radius from 5 to 8 m to decrease the growth rate of the m = 1, k = O instabdi~ ,pnd to accommodate the technical characteristics of the feedback apparatus. The theoretical MHD equilibrium of the toroidal Scyllac sector has been verified in detail. Plasma confinement is terminated in 6 to 12 psec by m = 1, k = O transverse motion, whose character has not yet been differentiated between instability and 10SSof equilibrium. Confinement times are approxi- mately equal to the transit time of rotational effects from the ends, which are observed to have an appreciable effect on the loss of confinement The linear Scyllac has provided scaling data on end loss and electron temperature with plasma length which confirm the simple theories. However, the huge effects of end stoppering predicted by theory for high-~ mirrors are not realized. The ZT-1 toroidal high-~ Z pinch has provided extensive data on field profiles and has been brought into full operation with crowbarring and reversed toroidaJ field. There are indications that as the stable reversed-field distribution with positive pressure gra&ent on axis is approached, the stability of the discharge is increased. k one particular case, good stabiity for 7 psec, termi- nated by a (possibly dtffusive) change to unstable field profiles, is seen. A laser-scattering apparatus is being appIied to the device. The experimental work on anomalous absorption of electromagnetic waves near the electron-plasma frequency has produced extensive resuks on anoma- lous resistivity and the coupling of electric fields to collective plasma modes. The resistivity agrees with theory at low electric fields for underdense plasmas. However, for up near to u (the microwave frequency), and for higher electric fields, strong anomalous or enhanced resistivity due to the parametric excita- tion of phsma waves is observed. This is correlated with quantitative measure- ments of the energy spectrum of the anomalously heated electrons. These restdts may have far-reaching comotations in the anomidous resistance of Tokamaks, laser plasma heating, and heating of plasmas in various confinement experiments. Work has begun on implosion heating of d pinches in higher-voltage regimes. ‘fhis work is of primary importance to the staged d-pinch concept to be incorporated into the O-pinch scientific feasibili~ expcrimen~ High+ plasma theory has had an exceptionally fruitful year, both in respect to Scyllac and high-toroidaI Z pinches. In the Scyllac context, the plausl%ility of wall stabilization of the m = 1, k = O mode has heen strengthened by investigation of MHD mode structures in !2= O and Q= 1 systems with diffuse plasma profiles. This provides theoretical justification for far-reaching plans to eliminate feedback stabilization in staged 6 pinches. Work is beginning on 1 equilibria and stabiity of toroidal Z pinches with noncircular cross sections (belt pinches) and continues to demonstrate stable high-p programmed diffuse pinch distributions appropriate to ZT-1. in the area of reactor technology we now have a program approaching maturity, with interrelated systems design and reactor core design, and related neutronics programs and materials research. A conceptual design in collabor- ation with the Argonne Natiomd hboratory will he completed in the next half year. in the superconducting magnetic energy storage research, rhe 20-kJ experi- ment has served to show solutions for switch material choice and construction. It also demonstrates the systematic of “current” switching by exceeding the critical current density and “latching” by heating to above the critical temper- ature. A 300-kJ apparatus is under construction. 11.THETA-PINCH PROGRAM A. Summary of O-pinch Activities (G. A. Sawyer) groove regions or provided for the addition of small vertical fields. In all cases there was a persistent sideways During the past year an extensive series of experiments motion of the plasma (probably the m = 1, k = O instabil- on the Scyllac toroidal sector was completed (Sec. 11.B), ity), which carried it to the wall in 6 to 12 psec. When the and conversion of the apparatus to the full Scyllac torus length of the toroidal sector was decreased from 5 to 3 m, has been started. The toroidal sector was operated with the onset of the plasma motion moved earlier; also, the nine variations of I = O and Q= 1 magnetic fields to fur- plasma behavior became more reproducible. This result nish equilibrium against the toroidal drift force FR. The leads us to believe that end effects have influenced plasma Q= O bumpy field was slways furnished by grooving the behavior in the toroidal sector. main compression coiL In the early experiments, the Experiments on the 5-m linear Scyllac began in March