LIU-SPS Open C-core MKE Extraction Review Discussion and concluding remarks

2. LIU-SPS Open C-core MKE Extraction ReviewDiscussion and concluding remarks Jan Uythoven & Carlo Zannini20 March 2013 Jan Uythoven, LIU-SPS Open C-core MKE Extraction Kicker Review 20 March 2013

3. IntroductionBrennan Goddard • Medium Term Plan 2013 should contain ‘final’ LIU project definition • Decision to be made by October • Decide on baseline upgrades, including MKE which has shown limitations in the past • Is the present system adequate for future beams? • If not, is the open C-kicker to be further explored?

4. Performance of existing MKEGlen Vanbavinckhove • HL-LHC factor 2.2 larger bunch intensities for 25 ns and 50 ns spacing • Large reduction in Re Z due to serigraphy. Resonance – peak at 45 MHz – can be reduced by staggering the lines ?? Total power will stay the same • Gain about a factor 2 in kicker temperature by serigraphy. • For HL beams we would reach about 75 degr measured (70 degr is IL), during scrubbing run 25 ns. • For 50 ns beams gain about factor 3. With HL beams also about 75 degr. • Scaling squared w. bunch intensity confirmed. Bunch length important variation -> Q20 (longer bunches) or Q26 optics. Conservative so far. • With HL beams serigraphed, same power deposited as now with no serigraphed. • Issue now during srcubbing. Not normal operation. Gain bunch length Q20. • 25 ns better than 50 ns • Other kickers also possible limits: • MKP-L: double temperature rise than MKE serigraphed. Expect 150 degrees ferrite HL beams • MKD-V: similar to MKE serigraphed. No serigraphy[hy foreseen. Expect 128 degr. ferrites. • MKQH: worse than MKE non-serigraphed, similar to serigraphed. Worry is damage not tune measurement? Foreseen to put serigraphy. • Other improvements MKE • Chilled water and dark coated tank could significantly help

5. Kicker Impedance ModelCarlo Zannini • Conceptual design implementedbeam in and beam out • Portion of ferrite not screened by the ‘box’ (S2) varied • Will have gap between ‘box’ and ferrite (Mike) • When the beam is out, the impedance can be neglected. • No serigraphy assumed in simulations • When the beam is out, peaks shifted to higher frequencies • Higher impedance when beam is in – of course • Transverse impedance significantly increases relative to present • Longitudinal a shift but not an increase, shift to higher frequency • Power loss estimate, including beam in opening for 1 second • With LIU parameters factor 10 lower than present MKE with present beams: Heating of the kicker not an issue! • Confirm statement from Glen LIU – present operation

6. Effect of kicker impedance on beam – longitudinalElena Chapochnikova • Present kickers • Synchrotron frequency shift with: present serigraphed MKEs OK following beam measurements, similar to 2001. • MKE compared to all kicker, Im part about 1/5 of all kickers: OK • Minimum threshold of coupled bunch instability at flat top – loss of Landau damping. 48 MHz peak in impedance not very nice, improvement to be studied • Open C-kicker • Beam out: very low • Beam in: 3x higher ImZ/n and 3 times higher Re/z for complete system, at flat top, which is the most critical time, beam in only 100 ms. Long instability growth time > 1ms, damped by large dfs/fs. • SPS BQM can decide not to extract 50 ms before extraction if not stable, but might not be able to measure. • With Q20 and double RF, at the limit for high intensity beams. • Prefer present MKEs above the open C non serigraphed • Study option of serigraphing open C

7. Effect of kicker impedance on beam – TransverseBenoit Salvant • Results are preliminary – needs more serious studies… • Beam out: small impedance. Thresholds for instabilities will increase at injection, good news • Beam in: larger vertical impedance, by 30 %, moved to higher frequencies, peaks at low frequencies • However, beam is stiffer at higher energy: gain factor 17… • Injection remains more critical: factor 2 (really last minute) 3 / 6.5 / 8 / 17 worse at injection depending on assumed beam parameters. Further checks required. • TMCI should not be an issue, not with present nor future system (Elena) • Positive to go to open C MKE (preliminary), not expect to introduce a new limit

8. Feasibility of C-core SystemGlen Vanbavinckhove • Layout of kickers, bumps and trajectories for Q26 and Q20 optics • Bump of 78 mm • using four correctors presently installed, for both LSS4 / LSS6 • Strength to be increased of 43 % / 30 %. Above present current limit. Magnets to be replaced by MPSH type. • Larger aperture quads required at QF.41610 and QF.61610 • To check if the orbit can be measured with present system for such a large bump -> BPM system to be replaced • Dispersion matching and TPSG clearance to be studied • Apertures for slow extracted should be OK

9. Possible New MKE kicker systemMike Barnes • Presently two types: MKE-S and MKE-L, water cooled, all but one serigraphed. Parameter list. • Rise-time limited LSS4 only for CNGS beams: stopped • Future limit on rise time 6 us only • Future MKE. About 4 – 5 m length instead of present 8 m. One generator driving all magnets about 1.5 us rise time. Stay 10 Ohms, resistively terminated. • Each magnet faster because of reduction of magnet inductance. Stay below 1 us if individual generators • Magnet simulations – conducting box should not touch the ferrite. Legs of the box (S2 from Carlo) can be relatively small… • Field homogeneity OK – could possibly reduce depth of the magnet, which would reduce the bump height. Noses on ferrite preferred. • Return busbar preferred behind the box. • MKE tank not centred around circulating beam to allow for bumped beam • Bellows? • Cooling improvements can be applied to present system: SIGNIFICANT • Chilled water: gain up to 19 degrees • Emissivity of tank, 15 – 25 % of power radiated out of the tank. Radioactive.. • Different ferrites with higher Tc

10. Concluding remarks • A big Thank You to: • The Speakers for doing all the hard work • Brennan and Malika to get this all going • Julia for the great organisation