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Review MDs Transverse Damper from Run1 to Run2

Review MDs Transverse Damper from Run1 to Run2. r eported by W. Hofle for ADT & friends. A. Butterworth G. Kotzian T. Levens D. Valuch. LHC MSWG Special Meeting 02.09.2014. Overview. Run 1: Three types of “Sessions”: Commissioning Operational Developments Machine Developments

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Review MDs Transverse Damper from Run1 to Run2

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  1. W. Hofle @ LHC Studies WG Day 2.09.2014 Review MDs Transverse Damper from Run1 to Run2 reported by W. Hofle for ADT & friends A. Butterworth G. Kotzian T. Levens D. Valuch LHC MSWG Special Meeting 02.09.2014

  2. W. Hofle @ LHC Studies WG Day 2.09.2014 Overview • Run 1: Three types of “Sessions”: • Commissioning • Operational Developments • Machine Developments • Future ADT contributions to MDs dealt also elsewhere in today’s review: • Halo Cleaning (s. Redaelli) • Abort gap cleaning (AGC) and injection slot cleaning (J. Uythoven) • Quench Limits (B. Auchmann) • Instabilities (T. Pieloni) • Goals for ADT Team for 2015: • Re-commission features developed in Run 1 with new hardware and software following the upgrade of ADT electronics • Contribute to diagnostics for instability observation • Develop new modes of operation and complete pending developments • Investigate noise properties of ADT

  3. W. Hofle @ LHC Studies WG Day 2.09.2014 LHC Transverse Feedback - Post LS1 Plan Major upgrade in LS1 (2013-2014) • doubling # of pick-ups • complete re-cabling of PUs • new digital hardware • multiple ADCs and DACs • reduction of noise • flexibility for gain control • instability diagnostics (trigger !) • tune diagnostics (GPU) Pickup Q8 Pickup Q10 Production run of new digital board ready for SPS Re-commissioning  SPS now testbed D. Valuchet al. Evian 2014: https://indico.cern.ch/event/310353/session/4/contribution/14/material/paper/2.pdf

  4. W. Hofle @ LHC Studies WG Day 2.09.2014 Past and Future MD Subjects / operational development • Run 1: • Abort Gap and Injection Gap Cleaning • Transverse blow-up with noise • Modulation of Gain for Tune Loop compatibility • Tune measurement from ADT with active excitation • Tune measurement from ADT with passive excitation • Variation of gain in ramp • Damper noise and emittance blow-up with colliding beams • Run 2: Subjects not completed and to be continued: • Improvements to Abort Gap Cleaning (bipolar pulse) • Tune Measurement • Tuning of 25 ns operation • Noise studies • Run 2: New subjects: • Halo Cleaning with coherent excitation  Stefano • Improvements to Loss Maps (loss maps with full beam & energy)  Stefano • New modes of operation (digital filters) to be tested on upgraded SPS damper first

  5. W. Hofle @ LHC Studies WG Day 2.09.2014 Abort Gap Cleaning (Abort Gap Monitor (Synchrotron Light) 2009 3 ms Time (turns) Time (within turn) • Abort Gap Cleaning by ADT (DDS) in V-plane stepping through a range of frequencies • Injection Gap Cleaning by ADT in H-plane • New ADT development: bi-polar envelope for start-up • New BSRT development: automatic switch on in coast M. Meddahi et al. IPAC’10 B. Goddard et al. IPAC’11 E. Gianfelice-Wendt et al. IPAC’12

  6. W. Hofle @ LHC Studies WG Day 2.09.2014 Selective Transverse Blow-up gate, 11 ms (example) • “White noise” i.e. pseudo-random numbers generated on FPGA • clocked at 40 MS/s • aperture measurements by blow-up • loss maps for collimation set-up • dynamic aperture • collimation quench tests (500+ kW) • knock out of bunches •  any kind of excitation can be gated • (also DDS produced narrow band) Wire scanner measurements (normalized transverse emittance) 2 mm 18 mm IPAC’12 MOPWO050 stops at 18 mm  aperture aperture measurement using blow-up with transverse damper

  7. W. Hofle @ LHC Studies WG Day 2.09.2014 Comparison loss maps 3rd order resonance damper loss map New development plan for 2015: making loss maps with gated excitation at end of fill with full beam intensity at top energy and in ramp Loss Maps: V. J. Moens, S. Redaelliet al. IPAC’13 MOPWO050

  8. W. Hofle @ LHC Studies WG Day 2.09.2014 Impact on Tune Measurement System (LHC) feedback gain with damper, max gain used • less broadening with lower gain • reduction of tune peak, i.e. • increase residual oscillations by more than 20 dB R. Steinhagen PAC’11, N.Y. • solution deployed in 2012: ADT gain modulation within turn and gated BBQ • 6 bunches are used for the Tune Measurement, these have low ADT gain

  9. W. Hofle @ LHC Studies WG Day 2.09.2014 ADT through the cycle - gain LSA:0.25 LSA:0.02 D. Valuch @ Evian 2011

  10. W. Hofle @ LHC Studies WG Day 2.09.2014 Fast Losses with ADT Simulating “UFO” Type Losses for Quench Test evolution of beam oscillation amplitude Fast losses (BLM signal) 1 ms Transverse Feedback was used as exciter in three quench tests carried out in February 2013 IPAC’13 M. Sapinski et al. WEPME044 and THEA045 (Fast Losses and Quench Tests)

  11. W. Hofle @ LHC Studies WG Day 2.09.2014 Shaping Time Domain Response Condition for h(nTb) = 0  symmetry of roll off • Motivated by appearance of single bunch instabilities • Used operationally for squeeze • and 25 ns spacing tests • Causes additional blow-up •  follow-up W. Hofle et al., IPAC’13 WEPME043

  12. W. Hofle @ LHC Studies WG Day 2.09.2014 Performance with Bunch Trains in LHC 2012 50 ns bunch spacing standard + hold 144 bunches (4x36) 25 ns bunch spacing enhanced bandwidth 144 bunches (2x72) Injection oscillation damping IPAC’13 W. Hofle et al., WEPME43

  13. W. Hofle @ LHC Studies WG Day 2.09.2014 Bunch-by-Bunch cont’d – 25 ns sensitivity to internal bunch motion even for 2015 odd shortest MD: two shots August 26, 2011 [in midst of 25 ns setting-up] G. Kotzian, ABP-HSC meeting 22.01.2014 D. Valuch et al., Evian 2014

  14. W. Hofle @ LHC Studies WG Day 2.09.2014 Tune Measurement from ADT data - active ADT excitation • 2730 turns  resolution too limited to clearly resolve peaks • (20 Hz apart) • Repeat in 2015 • lower gain on leading 6 (12 bunches) • Longer acquisition buffers F. Dubouchet et al. IBIC’13, TUPF29

  15. W. Hofle @ LHC Studies WG Day 2.09.2014 Tune Measurement from ADT data- passive observation cleaning (injection) time high gain (@450 GeV) (trench @tune) lower gain (average over 6 bunches) parasitic lines ! (ramp) tune change at start of squeeze (0.280.31) (4 TeV) tune (H) F. Dubouchet et al. IBIC’13 TUPF29 Based on recording of 6 bunches (horizontal plane) (also considering and tested excitation by short burst gated on 6 bunches)

  16. W. Hofle @ LHC Studies WG Day 2.09.2014 Proposal from 2012: ADT MD with noise and gain variation for LHC MD block 2 / 2012 Motivation: Probe interplay of damper gain and noise for minimization of emittance blow-up • two ramps with • 8 bunches per beam at 1.5x1011 • filling pattern with at least one bunch with • no collisions • collisions in IP1 and IP5 • collisions in IP1, IP5 and IP8 • collisions in IP8 only • With colliding beams at 4 TeV in adjust: • 1st fill: different levels of noise with ADT at constant ADT gain •  measure blow-up and bunch-by-bunch lumi • 2nd fill: based on results of previous fill inject a fixed level of noise with ADT and • observe the effect of a change of gain on the lumi and the emittance • 2012: Joint MD with BB team: not sufficient time to complete the program above  2015 V. Lebedev et al. IPAC’11, MOPO013

  17. W. Hofle @ LHC Studies WG Day 2.09.2014 Summary Incoming Operational Development 2015 • Exploration of injection oscillation and instability diagnostics via Observation Box • Abort Gap Cleaning improvements (as needed) • Damping of Scrubbing Beam, optimization of 25 ns running (when scheduled) • Tune Measurement with ADT: active excitation of leading bunch train 1st priority • When stable ADT tune measurement  tune loop using ADT can be envisaged • Tune measurement with observation box w/o excitation  when operational • Efficient loss maps with full beam / during ramp and end of fill Proposed (real) MDs for 2015 • Halo Cleaning using Transverse Damper (S.R.) • Bench mark of blow-up equation with injected noise (W.H.)

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