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MKP-I Kicker System Design and Feasibility

MKP-I Kicker System Design and Feasibility. M. Barnes, L. Ducimetiere, T . Kramer , L. Sermeus E. Carlier, B. Goddard, W. Höfle , R. Noulibos, G. Kotzian, B. Salvant, J. Uythoven, F. Velotti, C. Zannini. Outline. Overview of present system Design requirements Rise time studies

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MKP-I Kicker System Design and Feasibility

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  1. MKP-IKicker System Design and Feasibility M. Barnes, L. Ducimetiere,T. Kramer , L. Sermeus E. Carlier, B. Goddard, W. Höfle, R. Noulibos, G. Kotzian, B. Salvant, J. Uythoven, F. Velotti, C. Zannini LIU-SPS 50 ns Injection System for Pb Ions Review, October 4TH 2013

  2. Outline LIU-SPS 50 ns Injection System for Pb Ions Review Overview of present system Design requirements Rise time studies Circuit and magnet design Overview of variants studied Costs Conclusions

  3. Present Installation 145 (2-98%) Photos: J.Uythoven MKPS MKPS MKPL MKPS MKP-I LIU-SPS 50 ns Injection System for Pb Ions Review

  4. LIU-SPS 50 ns Injection System for Pb Ions Review

  5. RP Survey 2013 LIU-SPS 50 ns Injection System for Pb Ions Review Current injection kicker are immediately after the internal dump To be considered when discussing modifications.

  6. MKP-I Initial Design Requirements h v LIU-SPS 50 ns Injection System for Pb Ions Review

  7. “Our” Constraints & Assumptions LIU-SPS 50 ns Injection System for Pb Ions Review Would like to avoid SF6 gas filled cables. Voltage below 40 kV. Would like to avoid costs of moving the generators into a gallery close to the magnets. 200 m long Tx cables. Magnet cell length should not be much shorter than 28mm to ease assembly. Reuse of existing designs as far as possible. Short flat top will allow for PFL. It was suggested to start the design with a low number of cells per magnet.

  8. Verification of Initial Design Parameters: Rise Time 50 ns (10-90%)  feasible 45ns injected bunches Circulating bunch 100ns 50ns Waveform shown for 50, 5 cell magnet LIU-SPS 50 ns Injection System for Pb Ions Review

  9. Rise Time Definition: 50ns (10% to 90%) Head & tail of the bunch will see different B-field: ~2.7mT vs. ~4.7mT ∆=2mT ~ 50% 5 ns LIU-SPS 50 ns Injection System for Pb Ions Review

  10. +/- 1% Ripple ? 32.0mT vs. 34.2mT ∆=2.2mT ~6.6% Rise time jitter 5 ns (Thyratron + Trigger electronics) 5 ns LIU-SPS 50 ns Injection System for Pb Ions Review

  11. Rise Time LIU-SPS 50 ns Injection System for Pb Ions Review • Assumed 50 ns (10% to 90%) from preliminary studies could just be met however: • Considering a 5ns bucket length a 50 ns bunch spacing means in fact 45 ns rise time; • Considering a 5 ns jitter will already require a 40 ns rise time. • Different kick on head/tail to be studied (cannot be damped by the transverse damper!) (see presentation from Gerd) • Transverse damper cannot damp a kick amplitude mismatch of 10% without substantial emittanceblow-up (see presentation from Gerd) • Actual rise time (10-90%) would need to be in the range of <30 ns • New definition required! • Relaxation to 75ns but 2% to 98% and 2% ripple?

  12. Early Drafts LIU-SPS 50 ns Injection System for Pb Ions Review • Considered longitudinal separation of modules and tanks. ⟹ Total physical length increases compared to previous drafts. • Terminated 50 Ω magnet does not deliver the required kick strength per meter for 4.25 m total length and 40 kV. ⟹ Decision to go for system in short circuited mode. Advantage: no regular exchange/inspection of termination resistor -> less dose)

  13. Parameters for 50/25 Ω SC 25ΩMagnet to avoid SF6 cables? Can gain 21cm by having longer (&less) magnets. Filling time (25Ω): Shorter magnets needed to compensate for lower impedance LIU-SPS 50 ns Injection System for Pb Ions Review

  14. Circuit and Rise time Analysis • Modified existing Booster EK PSpice Model* • 2 magnets per PFL * very detailed EK system model done by L. Sermeus LIU-SPS 50 ns Injection System for Pb Ions Review

  15. PSpiceModel of Magnet Module * very detailed EK magnet model done by L. Sermeus LIU-SPS 50 ns Injection System for Pb Ions Review Modified from existing* Booster EK-magnet model:

  16. Results 50Ω SC 50 ns (10-90%) 62 ns (5%-95%) 72 ns (2%-98%) Ripple within ±2% 2 magnets per PFL (25Ω thus 2 x RG220) LIU-SPS 50 ns Injection System for Pb Ions Review

  17. Results 25Ω SC 55.2 ns (10-90%) 65 ns (5%-95%) 74 ns (2%-98%) Ripple within ±2% 61.5ns (10-90%) 70 ns (5%-95%) 80 ns (2%-98%) Ripple within ±2% 2 magnets per PFL (12.5Ω thus 4 x RG220) LIU-SPS 50 ns Injection System for Pb Ions Review

  18. Magnet Design LIU-SPS 50 ns Injection System for Pb Ions Review

  19. 5-cell magnet module assembly Magnet Module HV-plate Magnet Cell Ferrite Earth-plate

  20. Module / Tank Separation MKP: 139 (272.3) mm MKP: 140 (229) mm MKP: 137 mm LIU-SPS 50 ns Injection System for Pb Ions Review

  21. Ferrite cross section xx 105 45 40 Ferrite HV- Conductor Inj. Beam 125 yy 44 dumped p+ beam 50 40 Return- Conductor Shielding box (not necessary for dumped beam)

  22. Yoke Flux Density Flux in back leg ~110 mT Ferrite: 45 mm (MKPS: 60mm) (Cross section can be made smaller during detailed design.) I=1600 A LIU-SPS 50 ns Injection System for Pb Ions Review

  23. Good field region 5 sigma beam envelopes*:FT: 75.73 mmLHC: 32.72 mm Ions: 24.41 mm By(0/0)= 0.0414 T Static simulation only, no end effects; (first guess). * Courtesy: F.Velotti LIU-SPS 50 ns Injection System for Pb Ions Review ±0.5% Horizontally: -40 to +30 mm Vertically: +/- 17 mm

  24. HV/Earth-Plates Very similar sizes to current MKP magnets LIU-SPS 50 ns Injection System for Pb Ions Review

  25. Switch Possible choice, (variant used for PSB EK): LIU-SPS 50 ns Injection System for Pb Ions Review

  26. Cable LIU-SPS 50 ns Injection System for Pb Ions Review • RG220U • Up to 40 kV • Rather cheap (~50 CHF/m) • Other option: ~25 Ω, 80kV, SF6 gas filled cable • considered to be purchased for PS, however very difficult to obtain. • Considered to be much more expensive, detailed costs currently unknown. • Would need whole infrastructure for handling the gas as well. • Gas is definitely not halogen free -> IS23

  27. Beam Impedance?? LIU-SPS 50 ns Injection System for Pb Ions Review See presentation from Carlo and Benoit for details. It is already a known possible issue for the present MKP magnets and HL beams. Additional magnets (similar construction) will definitely not improve the situation. Thus a new magnet design should take any possibility for improvement into account. Without having the detailed data an enlarged vertical aperture was already studied.

  28. Additional Options Studied Enlarged Aperture MKPS+PFL LIU-SPS 50 ns Injection System for Pb Ions Review

  29. Enlarged Vertical Aperture LIU-SPS 50 ns Injection System for Pb Ions Review • To improve beam impedance issues and to provide aperture for a possible beam screen • 56 mm (provides 6mm on each side) • Several ideas: • Wires. • Ceramic chamber/plates with coating. • Ceramic plates with stripes.

  30. Lets look into the magnet design first: 105 45 Ferrite 4 Silver painted stripes? Ceramic plate HV- Conductor 136 Inj. Beam 44 48 56 50 30 nm Ti- coating? 75 7 10 7 Earth- Conductor

  31. 25Ω SC Enlarged Aperture (I) Larger aperture (less field) has to be compensated by magnetic length. Not such a big change as h/v ratio is beneficial. LIU-SPS 50 ns Injection System for Pb Ions Review

  32. 25Ω SC Enlarged Aperture (II) Without any beam screen LIU-SPS 50 ns Injection System for Pb Ions Review 56ns (10-90%) 65 ns (5%-95%) 74.9 ns (2%-98%) Ripple within ±2%

  33. Ferrite Yoke Static simulation only (first guess). LIU-SPS 50 ns Injection System for Pb Ions Review BY = 35.5 mT (Opera) vs. 35.9 mT (calculation) Back leg: ~100 mT L’=2.65 µH/m

  34. Beam screen • Is it really necessary? • If yes, it will increase the field rise-time. • Several ideas - ceramic plate /chamber with coating/stripes seems easiest. • Once decided, detailed transient simulations need to be done. For indication only: Studies done for a 100ns kicker system (Ti-coated racetrack chamber) show substantial field delays above 30 nm Ti-coating thickness Courtesy: T. Stadlbauer LIU-SPS 50 ns Injection System for Pb Ions Review

  35. What about connecting a PFL to the existing kickers? LIU-SPS 50 ns Injection System for Pb Ions Review Connect present MKPS kicker to PFL as planned in 2001 (115ns). Can’t do the 50ns nor 75ns but possibly 100ns (2-98%). PFL is rather simple. Connections to present system / switches is a bit tricky/costly.

  36. Theoretical parameters MKPS+PFL • 10%-90%: 62ns • 5%-95%: 76ns • 2%-98%: 100ns • However undershoot of ~5% (to be optimized) Will not work without additional angle from septa (MSI-V) or auxiliary kicker. LIU-SPS 50 ns Injection System for Pb Ions Review

  37. MKPS and PFL LIU-SPS 50 ns Injection System for Pb Ions Review Magnets and Tx Cables already in place. 6 PFL per magnet pair + switch and filter circuits needed. PFL rather simple, connection box and switches is more challenging and needs to be studied in more detail.

  38. Overview (I) LIU-SPS 50 ns Injection System for Pb Ions Review

  39. Overview (II) LIU-SPS 50 ns Injection System for Pb Ions Review

  40. Cost Estimates *Switch between PFN/PFL not considered Dump switch & TDR suppressed! LIU-SPS 50 ns Injection System for Pb Ions Review

  41. Conclusions LIU-SPS 50 ns Injection System for Pb Ions Review • New kicker system in principal feasible with the constraints given (50ns 10-90%) however not practicable in the global view (blow-up). Thus: • Redefine rise-time & ripple. • Increase total system length (from 4.5 to ??) to stay with conventional cables. • Enlarged aperture (56mm) feasible. • For relaxed rise time a 25Ω SC system is preferred (shorter, no TMR). • In case a beam screen is needed detailed studies have to be done to determine the reduction in rise time. • Present MKPS could be upgraded to 100 ns (2-98%). • 40kV max (~2.6 mrad). • No extra SPS impedance. • No extra radiation dose.

  42. References LIU-SPS 50 ns Injection System for Pb Ions Review G. Schröder, Fast Pulsed Magnet Systems, CERN-SL-98-017 BT M. Barnes, Beam Transfer Devices: Septa & Kickers, proc. CAS 2009 B. Goddard, et. al., A new lead iopn injection system for the CERN SPS with 50ns rise time, proc. IPAC2013 L. Ducimetière, et. al., Upgrading the SPS injection kicker system for LHC requirements. J. Uythoven, The new SPS injection channel, proc. Chamonix IX, p.120 J. Uythoven, et. al., The future of the SPS injection channel, SL-Note-99-023 SLI M. Barnes,T. Stadlbauer, Determination of coating thickness for the MedAustron kicker magnets vacuum chambers, ES-111108-a-TST, Geneva, 2011

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