Charge to working group:
accelerator components/
beam dynamics
F. Gerigk, C. Prior

ESS-B initiative workshop,
16.-18.03.2...
Outline


  goals, expected results,
  scope of the session,
  accelerator design/beam parameters,
  key questions per sub...
goals, expected results
 goal of the workshop:
   bring together people working on subjects important to high-power
   spa...
This workshop is not a design
review of ESS!!



                                                                   4
    ...
...instead, this is where we start to develop
recommendations for any future high-power
         (long-pulse) spallation s...
scope of the session


  high-power, highly reliable front-ends,
  high-intensity light ion linacs: component design,
  pe...
beam parameter                                            linac design
how the basic target parameters influence the linac ...
beam parameters                                          linac design

                             target/instrument
    ...
linac constraints (simplified..)
                                                                         examples:
       ...
beam parameters                                         linac design
                         first order scaling...

 1 Ge...
beam parameters                                         linac design
                         first order scaling...

 1 Ge...
beam parameters                                         linac design
                         first order scaling...

 1 Ge...
beam parameters                                         linac design
                         first order scaling...

 1 Ge...
beam parameters                                          linac design

                             target/instrument
    ...
Questions with high impact on linac design/
cost/reliability:
 1.) linac:
    how strict is the limit of 1 MW/coupler? how...
Parameter review of
CERN SPL         CERN-AB-2008-067

  RF frequency & cryogenic
         temperature
                   ...
SPL (high-power version):
  HP-SPL (5 GeV)
                                                       102 MeV 160 MeV 732 MeV ...
RF frequency review: 704 MHz
     frequency                            704 MHz                                  1408 MHz
 ...
cryogenic temperature review: 2K
                                                       eq. capacity          el. power
  ...
questions to the working group:

  has anyone done a similar analysis?
  is there experience with high-power RF equipment ...
key questions per subject
      ....common to many SC high-power linacs
                                                  ...
further questions
                                                                            J. Galambos
 1.) instrumenta...
questions II
                                                                            J-L. Biarotte: fault
            ...
questions III

 4.) power converters:                                                     R. Cassel

   R&D effort to get ...
questions IV
 5.) low-beta cavities (<200 MeV):                                          M. Vretenenar

   optimum structu...
questions V
                                                                        S. Belomestnykh
 7.) power and HOM cou...
questions VI
                                           R. Duperrier                   A. Letchford
 9.) Front-ends:

   s...
questions VII
 9.) Collaborations:

   Which other projects have similar questions?



                                   ...
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ESS-Bilbao Initiative Workshop. Charge to working group: accelerator components/ beam dynamics

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Charge to working group:accelerator components/beam dynamics
F. Gerigk, C. Prior

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ESS-Bilbao Initiative Workshop. Charge to working group: accelerator components/ beam dynamics

  1. 1. Charge to working group: accelerator components/ beam dynamics F. Gerigk, C. Prior ESS-B initiative workshop, 16.-18.03.2009
  2. 2. Outline goals, expected results, scope of the session, accelerator design/beam parameters, key questions per subject, 2 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  3. 3. goals, expected results goal of the workshop: bring together people working on subjects important to high-power spallation sources, identify challenges of next generation machines, propose necessary R&D programs, identify common areas/interests with other projects. expected result: a summary document highlighting the challenges, addressing future prospects, define potential collaborative developments programmes, 3 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  4. 4. This workshop is not a design review of ESS!! 4 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  5. 5. ...instead, this is where we start to develop recommendations for any future high-power (long-pulse) spallation source 5 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  6. 6. scope of the session high-power, highly reliable front-ends, high-intensity light ion linacs: component design, performance of existing machines, reliability, synergies with ongoing and planned linac projects, low-energy superconducting structures (< 100 MeV?), 6 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  7. 7. beam parameter linac design how the basic target parameters influence the linac design 7 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  8. 8. beam parameters linac design target/instrument linac design requirements beam power ~ 5 MW ? ~ ms ? pulse width 1 GeV (... 3 GeV ?) ? beam energy ≤ 20 Hz (15,20,25 ??) ? repetition rate 8 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  9. 9. linac constraints (simplified..) examples: 150 mA: 6.7 MV peak power/coupler: max. cavity voltage: Ppeak≤1 MW Vacc=Ppeak/Ipulse,average 50 mA: 20 MV cavity gradient (+ n. 704 MHz: 5/6 cells frequency/number of of cav. families): cells per cavity 1300 MHz: 9/10 cells ≤ 20 - 25 MV/m average power/ 2 ms, 20 Hz: 40 kW coupler: ~50/120 kW Pav=Ppeak*(tpulse*frep) (TTF type 1300 2 ms, 40 Hz: 80 kW MHz/LHC 400 MHz) high current (150 mA) space charge: beam stability yields high probability for (emittance increase, loss limited machine beam loss, machine performance and/or activation) need for front-end funnel 9 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  10. 10. beam parameters linac design first order scaling... 1 GeV, 16.7 Hz, 2 150 mA, Eacc = 6.7 ms, 5 MW MV, linac length = l0 10 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  11. 11. beam parameters linac design first order scaling... 1 GeV, 16.7 Hz, 2 150 mA, Eacc = 6.7 ms, 5 MW MV, linac length = l0 3 GeV, 16.7 Hz, 2 50 mA, Eacc = 20 MV, ms, 5 MW linac length = l0 10 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  12. 12. beam parameters linac design first order scaling... 1 GeV, 16.7 Hz, 2 150 mA, Eacc = 6.7 ms, 5 MW MV, linac length = l0 3 GeV, 16.7 Hz, 2 50 mA, Eacc = 20 MV, ms, 5 MW linac length = l0 50 mA, Eacc = 20 2.5 GeV, 20 Hz, 2 MV, linac length = ms, 5 MW l0*16.7/20=0.83*l0 10 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  13. 13. beam parameters linac design first order scaling... 1 GeV, 16.7 Hz, 2 150 mA, Eacc = 6.7 ms, 5 MW MV, linac length = l0 3 GeV, 16.7 Hz, 2 50 mA, Eacc = 20 MV, ms, 5 MW linac length = l0 50 mA, Eacc = 20 2.5 GeV, 20 Hz, 2 MV, linac length = ms, 5 MW l0*16.7/20=0.83*l0 50 mA, Eacc = 20 2 GeV, 25 Hz, 2 MV, linac length = ms, 5 MW l0*16.7/25=0.67*l0 10 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  14. 14. beam parameters linac design target/instrument linac design requirements beam power ~ 5 MW fixed ~ ms fixed pulse width high/low pulse beam energy 1 GeV (... 3 GeV ?) current, length constant higher rep. rate repetition rate ≤ 20 Hz (15,20,25 ??) shorter linac 11 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  15. 15. Questions with high impact on linac design/ cost/reliability: 1.) linac: how strict is the limit of 1 MW/coupler? how difficult are 2 couplers/ cavity? are 20 - 25 MV/m realistic? source/front-end limitations (current/time structure)? 2.) beam dynamics: what are the current limits to avoid a funnel in the front-end? current limits for low-loss operation in the linac? 3.) target: how do different energies (1,2,3 GeV) and rep-rates (16, 20, 25 Hz ..) influence the target design? 4.) instruments: how hard is the limit on the repetition rate (16, 20, 25 Hz ..)? 12 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  16. 16. Parameter review of CERN SPL CERN-AB-2008-067 RF frequency & cryogenic temperature 13 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  17. 17. SPL (high-power version): HP-SPL (5 GeV) 102 MeV 160 MeV 732 MeV 5 GeV 50 MeV 3 MeV H- source RFQ DTL chopper CCDTL PIMS β=1.0 β=0.65 352.2 MHz 704.4 MHz kinetic energy 5 GeV beam power 3-8 MW repetition rate 50 Hz pulse length up to1.2 ms average pulse current 0-40 mA cavity gradient (β=0.65/1.0) 19/25 MV/m protons p. pulse 1.5 1014 length (SC linac) 472 m 14 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  18. 18. RF frequency review: 704 MHz frequency 704 MHz 1408 MHz 472 m +12% length 246 +15% Ncavities 2 3 Nβ-families 5.6/8.2/6.8 6.3/7.8/12.1 ε-growth (x/y/z) lossy runs for realistic RF none in simulations long. beam loss gradient/phase variations IBBU,704 1/(8..128) BBU (HOM) normal risk 2..4 higher risk trapped modes RF power density limit (RF ok problematic distribution) difficult klystrons comfortable: MBK overall power consumption 28 MW up to -30% (RF+cryo, nom. SPL) more bulky saves tunnel space power converter 15 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  19. 19. cryogenic temperature review: 2K eq. capacity el. power @ 704 MHz T [K] @ 4.5 K [kW] [MW] HP SPL, 2% beam d.c. (4% cryo 2 19.4 4.48 d.c.) HP SPL, 2% beam d.c. (4% cryo 4.5 104 26.0 d.c.) LP SPL, 0.24% beam d.c. (0.32% 2 6.1 1.5 cryo d.c.) LP SPL, 0.24% beam d.c. (0.32% 4.5 11 2.75 cryo d.c.) not clear that 25 MV/m can be achieved at 4.5 K! 16 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  20. 20. questions to the working group: has anyone done a similar analysis? is there experience with high-power RF equipment at high duty cycle (~5%) for high frequencies (≥1200 MHz): klystrons, circulators, RF loads, phase shifters, splitters,... sensitivity to higher order modes for high-current machines (50/150 mA)? Is there any relevant experience? Dedicated workshop on HOMs in high-power linacs will take place at CERN (~June, exact date to be decided) 17 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  21. 21. key questions per subject ....common to many SC high-power linacs 18 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  22. 22. further questions J. Galambos 1.) instrumentation: high power proton machines: how can we do profile measurements during regular operation? ionisation detector readings disturbed by X-rays from the cavities, neutron detectors? halo diagnostics (loss management) 10-5 - 10-6 fractional beam?, localised beam loss measurements in well shielded low-energy beam (<100 MeV)?, P. Ostroumov high-energy emittance measurements?, beam instrumentation inside accelerating structures?, beam centre, profile, emittance to <1%? 19 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  23. 23. questions II J-L. Biarotte: fault tolerance 2.) reliability (spare parts): for which machine elements are spares necessary? (apart from the obvious ones..): source, RFQ, cryo-modules (how many), 3.) cryo-modules: how many layers of insulation? how many cavities per module? length of cryo-modules? warm or cold focusing magnets? conversion of electron modules (TTF/XFEL) for protons? parallel handling of 2K and 4K two phase circuits? P. Pierini pressure vessel codes conformance issues? interplay of module and cryo-system design? Dedicated workshop on segmentation of cryo-modules will be organised by FNAL/CERN (~September, exact date to be decided) 20 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  24. 24. questions III 4.) power converters: R. Cassel R&D effort to get a reliable, high duty cycle pulsed power supply? can we use a DC power supply with pulsed mod-Anode power supply for RF test stands? instead of pulsed power supplies (or even for machine operation?), size? operational impact? droop? (can it be compensated by LLRF?) how much distance can we have between a modulator and the klystrons? 1, 10, 100 m? state of the art in cables? cost comparison to housing the modulators in the tunnel? 21 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  25. 25. questions IV 5.) low-beta cavities (<200 MeV): M. Vretenenar optimum structures (NC or SC) for various beta regions?, simplification/standardisation of mechanical construction/ tuning?, E. Zaplatin influence of low-loss beam dynamics on structure design? 6.) medium/high-beta SC cavities: S. Bousson transition energies NC/spoke/elliptical, how many cavity families, realistic gradients for each structure type (and beta), best recipes for surface treatment, 22 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  26. 26. questions V S. Belomestnykh 7.) power and HOM couplers: peak/average power limits? adaption/re-design of existing devices for different frequencies? damping requirements (beam dynamics)? power and HOM couplers for spoke cavities? 8.) RF power splitting: R. Pasquinelli how many cavities per klystron? fast amplitude/phase shifters (high duty cycle)? flexibility/reliability compared to single sources? 23 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  27. 27. questions VI R. Duperrier A. Letchford 9.) Front-ends: space charge limits? source, LEBT (space charge compensation), RFQ? 10.) Linac modelling: J. Stovall how close are simulations to reality? code capabilities? C. Prior do we understand LEBT modelling? M. Seidel 11.) machine activation: beam loss in high-power machines 24 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
  28. 28. questions VII 9.) Collaborations: Which other projects have similar questions? A. Mosnier 25 “Accelerator Components”, ESS-B workshop 2009, F. Gerigk
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