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Status Update and Future Plans for FCC- hh Injection Protection

Status Update and Future Plans for FCC- hh Injection Protection. Elisabeth Renner, Mike Barnes, Wolfgang Bartmann , Chiara Bracco, Florian Burkart , Agnieska Chmielinska , Brennan Goddard, Francesco Velotti, David Woog. Outline. Batch length definition as main driver for injection design

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Status Update and Future Plans for FCC- hh Injection Protection

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  1. Status Update and Future Plans for FCC-hh Injection Protection Elisabeth Renner, Mike Barnes, Wolfgang Bartmann, Chiara Bracco, Florian Burkart, AgnieskaChmielinska, Brennan Goddard, Francesco Velotti, David Woog

  2. Outline FCC-hh injection protection: Status update and future plans • Batch length definition as main driver for injection design • Recap of injection straight and transferline design • Background on injection failures • Protection Absorber requirements – no results yet • Simulation strategy for design and validation of injection process • Massless septum as protection device

  3. Motivation • large damage potential of the beam - injection protection needs to withstand entire batch at 3.3 TeV • special attention due to injection into side experiments (as in LHC) FCC-hh injection protection: Status update and future plans • Injection protection scheme has to prevent injection of damaging beam into FCC-hh. It consist of • active protection: interlock system • passive protection: Absorber

  4. Starting Point: Batch Length • Injection Dump (TDI) needs to survive impact of full batch. Reduce number of bunches per batch to stay below damage limits [1] • energy deposition studies [1] result in a maximum allowed stored beam energy of 5.4 MJ limitation to 80 bunches per transfer (4.2 MJ) FCC-hh injection protection: Status update and future plans

  5. Injection System Layout – Injection Straight QD TDI MKI QF MSI QD * • *current design: • # kicker modules: 17 (18) • module length: 1.75 m • Deflection per MKI: 0.01mrad FCC-hh injection protection: Status update and future plans

  6. Injection System Layout – Transfer Line • for now: transferline is matched to injection straight using LHC FODO cell optics • expected adjustments as result of injection protection efficiency studies: • optics might be adjusted to fulfill specifications for transfer line collimators (increase beta functions at absorber, ...) • include momentum collimation at beginning of TL. aim: momentum offset • challenges: • partly superconducting transferline • advantages: • long straight sections available (also valid for scSPS option), which provide flexibility for the design of an appropriate protection system FCC-hh injection protection: Status update and future plans

  7. Failures Scenarios occur during ... ... extraction from HEB to FCC ... transfer ... injection from transferline to FCC straight HEB transferline FCC-hh Injection dump: TDI + TCLIA + TCLIB Extraction protection, similar to injection Momentum collimation TCDI + masks: transferline collimation FCC-hh injection protection: Status update and future plans

  8. Relevant failure scenarios for injection protection • Interlock System prohibits beam transfer in case of non-nominal system parameters. (LHC: last check ~4ms before SPS extraction. To be revised for FCC) • Thus, the system can only fail with impact on beam during those 4ms • Failures during this time result in field changes impacting the beam  only fast/ultrafast failures relevant • Consider time constants of field decay (NC vs SC) • Active protection systems for fast failures (occurring <4ms before extraction; FMCM for e.g. MSE, BETS for MKI)  see appendix Table of components leading to main failure scenarios. Not exclusive FCC-hh injection protection: Status update and future plans

  9. Injection Kicker Failures I TDI hit in grazing impact by part of the batch for modularity of 18 MKI (preliminary aperture, starting point ~8-9 sigma. Expected to change) TDI figure courtesy [2] FCC-hh injection protection: Status update and future plans • Failure can occur, after transfer permit is given and generator starts being charged. • Failure can occur any time of charging process. •  Erratic kick strength of one MKI can be between 0% and 100% (and 200% for single kicker in case vacuum flash over) • trigger dump switch in case of an erratic reduced flattop

  10. Injection Kicker Failures II • LHC: pre-firing thyratron switches and related kicker erratics account for a few events per year  not optimal for FCC: • use semi conductor switches • use different generator concept: Inductive Adder (IA) • advantage: highly segmented pulse generator  20 Layers per generator/magnet with 24 Switches each layer. figure courtesy [2] • reduced failure probability (semi conductor switches / lower voltage per switch) • reduced impact on beam in case of failure (1 layer = 1/20 kicker  ~0.4 sigma). FCC-hh injection protection: Status update and future plans Stalk (secondary) magnetic core PCB primary winding insulation parallel branches

  11. Failures Scenarios occur during ... ... extraction from HEB to FCC ... transfer ... injection from transferline to FCC straight HEB transferline FCC-hh Injection dump: TDI + TCLIA + TCLIB Extraction protection, similar to injection Momentum collimation TCDI + masks: transferline collimation FCC-hh injection protection: Status update and future plans

  12. Transfer Line Collimators (TCDI) + Masks • protect downstream TL and FCC injection from extraction / TL failures. Bottleneck: Septum! • Start with adapted HL-LHC design, then iterate until attenuation and damage limits are fulfilled. • Good News for FCC-hh: • Long Straight section  enough space available • FODO cell can be adapted to guarantee optimum for shower propagation from TCDI to mask • add momentum collimation at beginning of straight TL section • flexibility to adapt phase advance between collimators figure courtesy [4] • Open: define limits Input/ comments appreciated! • Safe beam level?  FCCW2017: 1E10 p+. • Damage limit / Quench limit Nb3Sn? • Attenuation requirement? figure courtesy [5] FCC-hh injection protection: Status update and future plans

  13. Injection Dump (TDI) • protect downstream collider from injection failures (mainly injection kicker) • Start with adapted HL-LHC design, then iterate until attenuation and damage limits are fulfilled. • HL-HC: • TDI 90 deg phase to MKI • Auxiliary absorber TCLIA at 180+20 deg and TCLIB at 360-20 deg from TDI figure courtesy [2] • FCC-hh: • Damage limit: max. 80 bunches for 3.3 TeV(increase of 30% seems possible) [1] • potentially add vertical TDI if septum failure show to be problematic (not expected) • Worst case: Grazing impact. +-2sigma FCC-hh injection protection: Status update and future plans

  14. HEB (LHC) extraction to transferline • P1 and P8: Extraction system to transferline is basically a copy of the FCC injection system • P6: a dedicated beam dump system • Same studies as for TDI should be conducted for TCDQ of HEB-extraction. • Same mitigation strategies, however some differences: • HEB is filled with > 2000 bunches (in LHC) • interlock system must prohibit a consecutive pulsing of MKE  affect as few bunches as possible. • Dump in P6. • Should not be a showstopper but should be considered to have similar impact and probability as in FCC-hh injection FCC-hh injection protection: Status update and future plans

  15. Next Steps: Design and Validation of Injection Protection • Safe beam level / attenuation requirement? FCCW17: 1E10 p+? • Cooperationwith EN/STI forabsorberdamagelimits • Quenchlimit Nb3Sn? • Cooperationwithcollimationteamtoguaranteecollimationhierachy FCC-hh injection protection: Status update and future plans • start with adapted design from HL-LHC • assume reasonable errors for hardware (with respective time constants) • single passage particle tracking with pycollimate as scattering routine • (1-3) iterate until damage limits and attenuation requirements are fullfilled. • Define according hardware specifications (interlock, apertures etc)

  16. Massless Septum as Protection Device • ‘Extraction’ of miskicked beam through massless septum. • Miskicked beam passes high field region of septum • Non-kicked beam passes zero field region • Same function as QD, but it has a zero field interval instead of a point • No impact on optics of non-kicked beam • Preliminary values: 1m long, 0.65 T (FCCW17). To be confirmed if this is feasible / of interest. • Either dump beam on ‘External TDI’ or use masslesssepta to avoid grazing impact on TDI • Same idea for extraction from HEB FCC-hh injection protection: Status update and future plans

  17. Summary • Upcoming strong focus on injection protection design and validation using pycollimate as scattering routine • FCC-hh needs to be fully protected by TDI / TCLIA / TCLIB system for injection failures (aperture 10-11 sigma?) • Exchange with FLUKA / Collimation team • Assuming HL-LHC like absorber, damage limit >80 bunches for 3.3 TeV injection batch • Transfer line collimation: long straight sections provides high flexibility for protection design • Injection dump: New concepts such as massless septum could improve protection efficiency. Failure probability strongly reduced by new generator concept. • Define interlock levels for active protection/ flattop stability etc. and absorber apertures as result of the tracking studies (balance between protection/injection oscillation and availability) FCC-hh injection protection: Status update and future plans

  18. Thank you for your attention! [1] A. Lechner, “Injection/extraction protection devices and the dump”, FCC Design Meeting, 2017-12-07 [2] C. Bracco, “Injection: Hadron Beams”, Beam Transfer CAS 2017, Erice [3] T. Kramer et al. “Considerations for the injection and extraction kicker systems of a 100 TeV centre of mass FCC-hh collider”, IPAC’16, Busan, Korea (2016) [4] F. Velotti, “Higher brightness beams from the SPS for the HL-LHC era”, CERN-THESIS 2017 [5] V. Kain, “Machine Protection and Beam Quality during the LHC Injection Process”, CERN-THESIS 2005

  19. Injection Oscillations • Defined by level, at which hardware can be interlocked. • Estimate acceptable inj. oscillation and define required interlock level as design specification • Tighten interlock level  reduce availability but also injection oscillations • (e.g. shot to shot variation in LHC by dominated by MSE  rebuild MSE power converter should reduce inj. oscillations) • first scaling from HL-LHC: • +/- 1mm of inj. oscillation. can be taken for aperture/collimation considerations. (HL-LHC: 1.5 mm – pessimistic / upgrade of MSE power converter  1mm) • Value to be confirmed FCC-hh injection protection: Status update and future plans

  20. Injection System Layout – Injection Straight MSI MKI TDI M. Hofer FCC-hh injection protection: Status update and future plans

  21. Active Protection - LHC • Fast Extraction Interlock (FEI), gives transfer permit. Last check of system parameters last 4ms before extraction from SPS • resulting max. orbit excursion at last TCDIH / MSI for worst case failure around 7 sigma • Additional system: Fast Magnet Current Monitor (FMCM) • resulting max. orbit excursion at last TCDIH / MSI for worst case failure around 0.6 sigma • Additional system: BETS to control MKI voltage • in case of discrepancy (HL-LHC: 0.5%)  MKI not pulsed  injected beam • Define required interlock levels and estimate feasibility FCC-hh injection protection: Status update and future plans

  22. HL-LHC Absorber Parameters FCC-hh injection protection: Status update and future plans

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