CERN Accelerator School: Vacuum for Particle Accelerators seminar: MAX IV laboratory vacuum systems
Marek Grabski MAX IV vacuum team 13th June 2017 Lund, Sweden
CAS: Vacuum for Particle Accelerators 1 Marek Grabski, MAX IV, Lund, Sweden Contents • Introduction to synchrotron radiation sources, • MAX IV accelerator layout, 3 GeV storage ring: o vacuum system design, o NEG coating development, o installation, o vacuum system commissioning status, • 1.5 GeV storage ring layout, • Conclusions and future plans.
CAS: Vacuum for Particle Accelerators 2 Marek Grabski, MAX IV, Lund, Sweden What MAX IV provides?
MAX IV
MAX IV is a synchrotron light source providing radiation from 4 eV till 40 keV to the beamlines for experiments. www2.lbl.gov
CAS: Vacuum for Particle Accelerators 3 Marek Grabski, MAX IV, Lund, Sweden 1st, 2nd Generation light sources Radiation emission of a relativistic electron (stationary lab X-ray source brilliance as a function if frame of reference): time since discovery of X-rays in 1895 adiation/ Synchrotron ] radiation % , · /primers/synchrotron_r · A. Balerna, .Mobilio A. # Opening angle ±1/ γ , teaching iation · Rad [
ch/students__ Synchrotron to brilliance Introduction science.desy.de/resear - Electron Synchrotron bunches radiation st http://photon 1 generation light sources at high energy physics # = accelerator facilities (parasitic operation) · · · 0,1% nd The greater the brilliance, the more photons of a given wavelength and 2 generation light sources purpose built direction are concentrated on a spot per unit of time. facilities: bending magnet radiation then also Brilliance is mainly determined by the cross-section of the electron beam. insertion devices (wigglers)
CAS: Vacuum for Particle Accelerators 4 Marek Grabski, MAX IV, Lund, Sweden 3rd Generation light sources
Insertion device - periodic magnetic structure X-ray source brilliance as a function if (wiggler, undulator): time since discovery of X-rays in 1895
Synchrotron ] radiation % , · · # · [
Brilliance of 3
radiation source brilliance types:
3rd generation light sources: Shift to insertion devices (undulators) http://photon-science.desy.de/research/students__teaching/primers/synchrotron_radiation/index_eng.html CAS: Vacuum for Particle Accelerators 5 Marek Grabski, MAX IV, Lund, Sweden 4th Generation light sources?
4th Generation light sources, mainly Free Electron Lasers X-ray source brilliance as a function of (FELs) with brilliance higher from previous generation by time since discovery of X-rays in 1895 many orders of magnitude. ] MAX IV is storage ring based 4th generation light % , ·
source with brilliance higher by at least one order rd
of magnitude from 3 generation light sources. · # ·
At MAX IV: [
• Higher brilliance is achieved by lowering electron beam emittance, • Only insertion devices are used: wigglers, undulators, (no more bending magnet radiation). brilliance
4th generation light sources: at least 1 important parameter factor of 10 better than the previous generation. http://photon-science.desy.de/research/students__teaching/primers/synchrotron_radiation/index_eng.html CAS: Vacuum for Particle Accelerators 6 Marek Grabski, MAX IV, Lund, Sweden MAX IV layout Synchrotron light source facility in Lund, Sweden. 3.7 GeV Linear accelerator - Linac (300 m) Short pulse facility Electron gun 1.5 GeV 3 GeV storage storage ring Commissioning Commissioning started: ring for hard started: September 2016 for soft x-rays x-rays August 2015
https://www.maxiv.lu.se/
CAS: Vacuum for Particle Accelerators 7 Marek Grabski, MAX IV, Lund, Sweden MAX IV beamline layout
Beamline layout example (Biomax)
Insertion device (in-vacuum Undulator) Ring tunnel
Front End (masks, beam position, safety) Beamlines at MAX IV: 6 beamlines in operation/commissioning, Monochromator 5 being installed, (energy selection) 3 under design. Mirrors Sample (beam focusing) Total beamline capacity: ~30 beamlines Detector https://www.maxiv.lu.se/ CAS: Vacuum for Particle Accelerators 8 Marek Grabski, MAX IV, Lund, Sweden Before MAX IV ALBA vacuum system and other • Antechamber design with lumped copper absorbers. rd 3 generation storage rings • Keyhole profile 28x72 mm. Also ANKA, SLS, CLS, ASP, Diamond…etc. • Stainless steel 316LN. Keyhole profile • Pumping mainly by ion and NEG pumps. • Overall pump speed 60400 l/s
Bending The unit cell ≈13 m magnet 28 NEG pumps Cold cathode 72 gauge Bellows Lumped Bending absorbers magnet NEG pumps Ion pumps Cold cathode gauge Lumped RGA absorbers
CAS: Vacuum for Particle Accelerators 9 Marek Grabski, MAX IV, Lund, Sweden Conventional vs compact vacuum system
Conventional vacuum system
MAX IV (3 GeV storage ring) vacuum chambers
Lumped absorber NEG-coating
Size of 1 € coin
Ion Both vacuum systems types pump provide the same functions.
CAS: Vacuum for Particle Accelerators 10 Marek Grabski, MAX IV, Lund, Sweden MAX IV as 4th gen. light source The 3 GeV storage ring: what is special about it?
Brilliance mainly depends on the electron beam transverse size and divergence, product of which is called beam emittance ϵ. One way to increase the brilliance is to lower the emittance of the circulating beam.
γ – Lorentz factor (E/E0)
Emittance scaling: ∝ .
ρ – bending radius of NB – number of bending magnets bending magnets
CAS: Vacuum for Particle Accelerators 11 Marek Grabski, MAX IV, Lund, Sweden MAX IV as 4th gen. light source
1.5 GeV double-bend achromat (DBA) lattice: Energy: 1.5 GeV Horizontal Emittance 2 dipoles, (bare lattice): 6 nm rad 0 Bending angle: 30 Circumference: 96 m Bending radius: 3.8 m #straight sections: 12 x 3.3 m
3 GeV 7-bend achromat lattice: Dipole magnets 7 dipoles, Bending angle: 180 Bending radius: 19 m
Energy: 3 GeV Lattice of choice for the 3 GeV ring: 7-bend achromat Horizontal Emittance (multi-bend achromat). Choice of such lattice puts (bare lattice): 0.33 nm rad major constraints on the vacuum system design. Circumference: 528 m #straight sections: 20 x 4.5 m
MAX IV DDR
CAS: Vacuum for Particle Accelerators 12 Marek Grabski, MAX IV, Lund, Sweden 3 GeV achromat layout 7-bend achromat lattice, 1 achromat ~26m long
MAX IV DDR
- Magnetic field B=0.5 T, Straight section for - 1.50 and 30 bends. insertion devices
Magnet block
CAS: Vacuum for Particle Accelerators 13 Marek Grabski, MAX IV, Lund, Sweden 3 GeV magnet layout One achromat Photon beam - Total length ~26 m, - 4.5 m straight section (L)
Beam direction
U2, VC4
25mm Sextupole Corrector Dipole
Ø22 Ø25 (ID) Chamber ID 22mm
Magnet apertures Ø25mm Min. clearance with the iron 0.5 mm, min. clearance with the coils 2 mm.
CAS: Vacuum for Particle Accelerators 14 Marek Grabski, MAX IV, Lund, Sweden Vacuum system constraints and requirements
No space for • Compact lattice lumped absorbers Small longitudinal distance between magnets. • Closed solid magnet block Little place around the magnets. No space for lumped pumps • Small aperture of the magnets Ø25 Magnets’ aperture Ø25 mm. Low conductance
of vacuum tubes ) • Low target dynamic pressure 2 Average pressure 1e-9 mbar. Need of pumping Sextupole and low PSD • Removal of the SR power (BM & ID) (W/mm ensity Power d Power Power density along bent vacuum chamber walls and absorbers. Length (mm) • Extraction of synchrotron radiation Photon beam Limited by small bending angle. Electron beam • Stable positioning of BPM Disentangling the BPMs from the chambers.
CAS: Vacuum for Particle Accelerators 15 Marek Grabski, MAX IV, Lund, Sweden Vacuum system approach
• Geometry: inside diameter 22 mm, 1 mm wall Distributed cooling thickness, bends of 1.50 and 30 over 19 m radius. Ø22
• Substrate: Silver bearing (OFS) Copper vacuum OFS Dipole chambers (resistance to thermal cycling). COPPER
• Distributed water cooling to cope with SR.
• Areas made of stainless steel for fast corrector coils.
Crotch absorber • One Lumped absorber per achromat needed Area for fast corrector to extract the photon beam to the front ends. (stainless steel port)
• Welded bellows at vacuum chamber extremities to allow expansion without affecting the BPM position and temperature. NEG Bellows • Distributed pumping and low PSD all along coating the conductance limited chamber, utilizing thin film NEG-coating.
CAS: Vacuum for Particle Accelerators 16 Marek Grabski, MAX IV, Lund, Sweden 3 GeV ring layout Emittance Injection Energy: 3 GeV measurement Design current: 500 mA Horizontal Emittance: 0.33 nm rad Circumference: 528 m #straight sections: 20 x 4.5 m
Installed Insertion Devices: 2 In vacuum undulators (2 m long) • NanoMAX IVU18 100 MHz • BioMAX IVU18 RF cavities 2 EPU (4 m long, min gap 11 mm) • VERITAS EPU48 • HIPPIE EPU53 Landau 1 In vac. Wiggler (2.4 m long) cavities • BALDER IVW50 (300 MHz) Legend: • Dk: Dipole kicker (S1) • Mk: Multipole kicker (L) • LK: Longitudinal kicker (S2) • VP: Vertical pinger (S2) L=long straight, S=short straight,
CAS: Vacuum for Particle Accelerators 17 Marek Grabski, MAX IV, Lund, Sweden Standard vacuum chamber geometry One achromat
VC5 Beam direction
Welded VC5 chamber bellows
Chamber Material: OFS copper body Inside diameter: 22 mm, Cooling for Total length: 2.5 m, Ribs corrector Welded Bent part bellows Bent part Arc length: 1 m, Bending angle: 30, Distributed Bending radius: 19 m. cooling
Cooling for Vacuum system design was made NEG-coated. corrector in collaboration with CELLS-ALBA.
CAS: Vacuum for Particle Accelerators 18 Marek Grabski, MAX IV, Lund, Sweden General vacuum chamber geometry Power density deposited by synchrotron radiation on the outer wall of vacuum chamber vs. length Chamber body Ribs ] Cooling for corrector area ower [W/mm^2 ower
P Distributed cooling
Length [mm]
Ø22 mm
Welded bellows with RF shielding
CAS: Vacuum for Particle Accelerators 19 Marek Grabski, MAX IV, Lund, Sweden Vacuum achromat layout One achromat
Beam direction Penning gauge (S2)
One achromat VC9 Length: ~26m VC8 In each achromat: VC7 10 BPMs, 3 pumping ports (with ion VC6 pumps) and 1 pump in FE, Extractor 1 crotch absorber, VC5 gauge (S1) VC4 3 gate valves.
VC3 VC1 VC2 VC10 Straight section for insertion devices CAS: Vacuum for Particle Accelerators 20 Marek Grabski, MAX IV, Lund, Sweden BPM stability BPM (Beam Position Monitor)
Cooling Taper BPM electrodes To ensure thermal and dimensional stability of BPMs (Beam Position Monitor) : • RF shielded bellows at chamber extremities to allow pipe expansion without affecting the BPM position and temperature, • Taper to shield BPM stainless steel body RF shields from radiation, • Copper chamber water cooled all-along. Bellows
CAS: Vacuum for Particle Accelerators 21 Marek Grabski, MAX IV, Lund, Sweden Synchrotron light extraction One achromat Photon beam
VC2
Beam direction
BPM Crotch absorber VC2 BPM Photon beam
Short straight section 1 – synchrotron light extraction to the Front End and Beamline Crotch absorber
Radiation fan intercepted by absorber
CAS: Vacuum for Particle Accelerators 22 Marek Grabski, MAX IV, Lund, Sweden Chamber fixation 1. Flexible support: allows longitudinal movement of the chamber in order to release the stresses from the chamber and block the transversal movement. 2. Rigid support: fixes the chamber in the middle of the dipole part and keeps the chamber in its nominal position both in transversal plane and longitudinally, allowing the chamber to expand upstream and downstream towards the flexible supports 1. and 2 Bellows 1. Flexible 2. Rigid support support 1. Flexible support
Bellows
BPMs fixed to the magnet block
CAS: Vacuum for Particle Accelerators 23 Marek Grabski, MAX IV, Lund, Sweden NEG coating development
• NEG-coating of vacuum chambers by magnetron LHC warm sections sputtering was developed at CERN for warm LHC sections, 6 km of vacuum pipe was coated. • NEG-coating is used widely in many light sources - mainly for ID chambers. • At SOLEIL 56% of storage ring is NEG coated. • In MAX II since 2007 three dipole chambers were
replaced by NEG-coated vacuum chambers. ‘NEG thin film coatings: from the origin to the next- generation synchrotron-light sources’, P. Chiggiato, CERN (presented at OLAV’14)
CAS: Vacuum for Particle Accelerators 24 Marek Grabski, MAX IV, Lund, Sweden NEG-coating R&D at CERN
To validate the coating feasibility 3 main stages of NEG (Ti, Zr, V) coating validation by magnetron sputtering in collaboration with CERN were undertaken. (R&D duration ~2 years). 1. Define and perform initial surface treatment of OFS copper substrate. 2. Validate compatibility of NEG-coating (adhesion, thickness, activation behavior): a). on etched OFS copper. b). on wire-eroded surfaces and used brazing alloys. 3. NEG-coating validation of compact vacuum chamber geometries: a). Coating and testing of small diameter, bent tubes. b). Establish coating procedure/technology and coat chambers of complex geometry.
CAS: Vacuum for Particle Accelerators 25 Marek Grabski, MAX IV, Lund, Sweden 1. Surface treatment (R&D at CERN)
Basing on experience with LHC warm section vacuum chambers, chosen treatment was: Degreasing -> Etching -> Passivation. Etching was needed to remove about 50 μm of the material to ensure that the extruded copper tubes are free from contamination that could be trapped in the cortical layer of the substrate. Etching: Passivation:
NEG coating compatible
Ready for manufacturing
100% of tubes were visually inspected at each step of the cleaning process.
Observed defects: About 10% of the tubes were discarded by visual inspection at various stages of the cleaning process due to strong contamination.
CAS: Vacuum for Particle Accelerators 26 Marek Grabski, MAX IV, Lund, Sweden 2. and 3 a). Coating compatibility
Confirm compatibility of NEG-coating (Ti, Zr, V) on etched: • OFS copper tubes, wire eroded surfaces and brazing types (substrate), • for small diameter, bent tubes (geometry).
Chamber after coating NEG coating requirements: Chamber before coating and thermal cycling • No peel offs,
NEG-coating • Coating thickness 0.5 – 2 μm, • Correct composition of Zr, Ti, V, • Good activation behavior.
O 1s peak as a function of temperature
Surface metallic composition by XPS SEM thickness measurements: CERN 0.7 μm reference
CERN reference O 1s peak (A.U.) peak 1s O ic concentration (at. %) (at. concentration ic Metall 0 Activation temperature ( 0C) – 1h Coated chambers Activation temperature ( C) CAS: Vacuum for Particle Accelerators 27 Marek Grabski, MAX IV, Lund, Sweden 3. b) Complex vacuum chambers (R&D at CERN)
3 b). Establish coating procedure/technology and produce chambers of complex geometry: Vacuum chamber for beam extraction. BPM Crotch absorber VC2 BPM Photon beam
Beam direction
Aperture limiting sextupole VC2a VC2b
CAS: Vacuum for Particle Accelerators 28 Marek Grabski, MAX IV, Lund, Sweden 3. b) Complex vacuum chambers (R&D at CERN)
Prototype was made at CERN in two halves to allow easy inspection of the coating quality. Glow discharge during coating xit
0.75 m Chamber e Chamber Chamber entrance Chamber
Ø22 Ø25 7 Thickness – OK, Composition OK, X - ‘delayed‘ activation Due to difficulties with coating – chamber for 3 5
entrance coating was divided and coated in 2 runs. Chamber exit Chamber Chamber Chamber
VC2a VC2b
CAS: Vacuum for Particle Accelerators 29 Marek Grabski, MAX IV, Lund, Sweden NEG-coating series production Beam direction 3 GeV - 1One achromat achromat(~26m) Photon beam
VC10 VC2 VC4
Main vacuum chamber types: 1. Standard bent vacuum chambers (VC4) - 1.50 and 30 bends, Industry (70% length wise) 2.8 m (VC4) Ø22 mm 30
Ø22
2. Straight vacuum (VC10) chambers, Collaboration with ESRF (15%)
17.2 mm 2 m (VC10B)
BPM
VC2 3. Special vacuum chambers. Photon beam Collaboration with CERN (15%) Electron beam
CAS: Vacuum for Particle Accelerators 30 Marek Grabski, MAX IV, Lund, Sweden Activities at ESRF Photon stimulated desorption (PSD) measurements Courtesy of: H.P. Marques, M. Hahn - ESRF
at ESRF (beamline D31), chamber after activation. ) ph
/ MAX IV Chamber, NEG-coated OFS Run #1 OFS Cu, 3 m, Ø25 mm mol copper chamber ( At dose 4e22 ph/m Photon beam PSD yield = 1e-5 mol/ph PSDYield Run #2
Run #2 shows 10 times lower PSD yield NEG-coated OFS copper chamber Dose (ph/m)
CERN chamber, 316LN, 2 m, Ø60mm
At dose 4e22 ph/m PSD yield = 2e-6 mol/ph Measured PSD yield from Run #2 similar to what was measured before.
‘Synchrotron Radiation-Induced Desorption from a NEG-Coated Vacuum Chamber’, P. Chiggiato, R. Kersevan
CAS: Vacuum for Particle Accelerators 31 Marek Grabski, MAX IV, Lund, Sweden Installation procedure
Installation of NEG-coated ring Ring installation was tested and Actual installation started in rehearsed by installing and activating November 2014, ended June 2015 1 mockup achromat in summer 2014. Installation done with help from Budker Institute of Nuclear Physics (BINP) Strongback
7 magnet blocks 7 magnet blocks on concrete girders on concrete girders
CAS: Vacuum for Particle Accelerators 32 Marek Grabski, MAX IV, Lund, Sweden Installation procedure
• Assembly insitu (above magnets), • Pumpdown and testing, • Lifting,
Strongback
Assembly tables
CAS: Vacuum for Particle Accelerators 33 Marek Grabski, MAX IV, Lund, Sweden Installation procedure
• Baking (1 day), NEG activation (1 day),
Baking oven
CAS: Vacuum for Particle Accelerators 34 Marek Grabski, MAX IV, Lund, Sweden Installation procedure
One vacuum sector ready • Lowering to the bottom magnet half, • Installation of final equipment (supports, BPM cables), • closing magnet blocks.
CAS: Vacuum for Particle Accelerators 35 Marek Grabski, MAX IV, Lund, Sweden Coating non-conformities All the chambers were inspected at site before installation. Peeling-off Observed peeling-off: Peeling-off at the edge At RF fingers Cu-Be insert and Cu of stainless VC. Chamber end piece. RF fingers and Cu end not aproved for were not shielded properly installation. during coating. Solution: new pieces ordered and replaced (without coating). Severe peeling-off
Uncoated areas: Few cm^2 uncoated, in complex chambers. Uncoated areas
Peeling-off at RF fingers and Cu endpiece
CAS: Vacuum for Particle Accelerators 36 Marek Grabski, MAX IV, Lund, Sweden 3 GeV commissioning progress
3 GeV storage ring commissioning started in August 2015
Average base pressure: • Gauges 2e-10 mbar, • Ion pumps under range. 2nd shutdown
Accumulated beam dose 1st shutdown • 210 Ah (June 2017).
1st shutdown March 2016: • 2 in-vacuum undulators,
2nd shutdown August 2016: • 2 EPU chambers (8x36mm), • In-vacum wiggler.
CAS: Vacuum for Particle Accelerators 37 Marek Grabski, MAX IV, Lund, Sweden Pressure vs beam current, dose
Beam direction Extractor gauge
2E-09 Pressures at dose 16 Ah and 1E-09 @dose=16 Ah 95 Ah during beam ramp up. (pressure recorded by [mbar] 1E-09 av
extractor gauge at not NEG P coated crotch absorber in S1) 9E-10
7E-10
5E-10 @dose=95 Ah
3E-10 Average pressure pressure Average 1E-10 0 20 40 60 80 100 120 140 160 180 200 Beam current I [mA]
CAS: Vacuum for Particle Accelerators 38 Marek Grabski, MAX IV, Lund, Sweden Vacuum conditioning curve
Beam direction Extractor gauge
Normalized average pressure vs beam dose, ] A essure essure rise average pr average /I [mbar/m /I
av dP Normalized
CAS: Vacuum for Particle Accelerators 39 Marek Grabski, MAX IV, Lund, Sweden Lifetime evolution
Beam lifetime up to 6 Ah, Maximum stored beam current 198 mA
CAS: Vacuum for Particle Accelerators 40 Marek Grabski, MAX IV, Lund, Sweden 3 GeV ring Lifetime tests
One 4 ion pumps achromat per achromat Beam direction Ion pumps
Total beam lifetime [s] Pressure measurement 1e-8
A05 A13 A12 A09 A07 (30 h) OFF OFF OFF OFF OFF All Ion pumps ON
1e-9 (20 h) re [mbar] re
Tests done Beam lifetime [s] lifetime Beam Pressu @dose ~190Ah Seems that NEG is still A06 Beam current at A02 OFF Beam current pumping start 100 mA OFF at end 95 mA 1e-10 (1 h)
~1h 30 min Date CAS: Vacuum for Particle Accelerators 41 Marek Grabski, MAX IV, Lund, Sweden 3 GeV ring Lifetime tests - RGA
re [mbar] re Mass 2 (ioncurrent) Pressu
1e-10 Mass 16
Mass 15 Mass 14 1e-11 RGA in A05 Mass 28 Mass 12 Tests done 1e-12 Mass 17 @dose ~190Ah
Mass 84
1e-13 Mass 44
Other masses: 40, 35, 32, 19, 18, 4 1e-14
Ion pumps OFF
CAS: Vacuum for Particle Accelerators 42 Marek Grabski, MAX IV, Lund, Sweden Scraper measurements Mean lifetime vs vertical scraper Total average pressure along the beam path distance from the beam center (contribution from all gasses based on the RGA spectra (Done at beam dose 140 Ah) Z2 =5.77) (h) τ lifetime, Mean
Scraper position from beam center, y (mm) At 70 mA (dose 140 Ah):
Elastic beam lifetime τelastic = 163 h Inelastic beam lifetime τinelastic = 104 h Touschek lifetime τTouschek = 63 h Pressure as seen by the beam 7.3e-09 mbar
CAS: Vacuum for Particle Accelerators 43 Marek Grabski, MAX IV, Lund, Sweden Problems
Beam direction
• RF cavity (S2) venting due to broken high power feedthrough during conditioining (with closed valves). Now cavity is removed from the ring and dummy chamber placed as could not be run with high power anymore. Now awaits conditioning outside the ring. • Hot spots in proximity of crotch absorber (S1), mis-positioning of the crotch chamber, Hot spot
Photon beam
Electron beam
CAS: Vacuum for Particle Accelerators 44 Marek Grabski, MAX IV, Lund, Sweden 1.5 GeV storage ring layout
• 96m circumference • 12 DBA. • 12 straight sections of which, all for ID, except: • Ach. 1: injection • Ach. 5: RF straight Ach. 3: inj. Kicker +ID
CAS: Vacuum for Particle Accelerators 45 Marek Grabski, MAX IV, Lund, Sweden 1.5 GeV storage ring vacuum system
Upper magnet block Conventional vacuum system: • St. steel VC with lumped and distributed absorbers to intercept synchrotron radiation. • 5 Ion pumps, 1 TSP and 2 NEG strips.
One achromat. DBA lattice
Lower magnet block
NEG strips Ion pumps
Ion pumps TSP CAS: Vacuum for Particle Accelerators 46 Marek Grabski, MAX IV, Lund, Sweden 1.5 GeV storage ring vacuum system
Vacuum chamber during the testing.
20 mm
CAS: Vacuum for Particle Accelerators 47 Marek Grabski, MAX IV, Lund, Sweden 1.5 GeV storage ring installation
Assembly outside the tunnel Baking in-situ
Movable crane Strong-back
Assembly tables
Vacuum chambers installed in side the magnet blocks
CAS: Vacuum for Particle Accelerators 48 Marek Grabski, MAX IV, Lund, Sweden Ion pump pressure reading issues
Strong effect from photoelectrons in the reading of the ion pumps. Ion pumps
Magnet strip placed in some ion pumps to prevent photoelectrons entering Current ion pumps. Pressure Pressure reading reduced 32 times. Pressure [mbar] Pressure Beam current [mA] Beam current Magnet Magnet placed strip
Date CAS: Vacuum for Particle Accelerators 49 Marek Grabski, MAX IV, Lund, Sweden Conclusions and future developments Conclusions: • The application of NEG coating has to be considered from the beginning of machine design as it has many implications (geometry, manufacturing, cleaning etc), • Hot-spots from SR due to mis-positioning of some vacuum chambers, • Ion pumps strongly influenced by photoelectrons (up to factor of 40), • Discrepancy between pressure at the extraction/cold cathode gauges and average beamlife time pressure estimation, Ring • What is the behavior of NEG film at presence of synchrotron radiation?
Upgrades considered for synchrotron storage rings:
• Vacuum chamber outer diameter 10 mm, Storage Limited - • Compact vacuum system design, • Very low impedance flange/bellow assemblies, • Distributed pumping, low PSD.
Development needed for future storage rings: • Coating of 8 mm aperture, long, bend chambers, • Effective thin layer in-situ baking system (for robust re-activation and faster installation), • Handling of flexible, delicate and small vacuum pipes, • Study new materials possible for chamber manufacturing, Pedro F. Tavares, September 2014 September Tavares, F. Pedro
• New methods of coating (electroforming). - Preliminary Studies Towards a Diffraction Towards Preliminary Studies
CAS: Vacuum for Particle Accelerators 50 Marek Grabski, MAX IV, Lund, Sweden Thank you for your attention
Acknowledgments: Jonny Ahlbäck, Eshraq Al-Dmour, Jens Sundberg, Åke Andersson, Pedro F. Tavares (MAX IV), CERN, PKAB, ALBA, ESRF, BINP, Solaris and MAX IV staff
CAS: Vacuum for Particle Accelerators 51 Marek Grabski, MAX IV, Lund, Sweden