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

2. W. Hofle @ LHC Studies WG Day 2.09.2014 2 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 3 Milestones of Run 1 as reached: commissioning periods, operational developments and MDs First pick-up signals 2008 UPS noise crisis 2009 First abort gap cleaning test: December 2009 Damping single bunch: Spring 2010 Bunch trains @50 ns: 2010 High Lumi operation with 50 ns: 2011 Injection of noise, blow-up, aperture measurement, collimation set-up: 2012 Tests with 25 ns bunch spacing, bandwidth flattening: 2012 Exploration of tune measurement with ADT: 2012 Quench tests with ADT: 2013

4. LHC Transverse Feedback - Post LS1 Plan W. Hofle @ LHC Studies WG Day 2.09.2014 4 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) Major upgrade in LS1 (2013-2014) D. Valuch et al. Evian 2014: https://indico.cern.ch/event/310353/session/4/contribution/14/material/paper/2.pdf Pickup Q10 Pickup Q8 Production run of new digital board ready for SPS Re-commissioning  SPS now testbed

5. W. Hofle @ LHC Studies WG Day 2.09.2014 5 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

6. Abort Gap Cleaning W. Hofle @ LHC Studies WG Day 2.09.2014 6 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 Time (turns) Time (within turn) 3  s (Abort Gap Monitor (Synchrotron Light) M. Meddahi et al. IPAC’10 B. Goddard et al. IPAC’11 E. Gianfelice-Wendt et al. IPAC’12 2009

7. Selective Transverse Blow-up stops at 18  m  aperture W. Hofle @ LHC Studies WG Day 2.09.2014 7 aperture measurement using blow-up with transverse damper Wire scanner measurements (normalized transverse emittance) 18  m 2  m “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) gate, 11  s (example) IPAC’12 MOPWO050

8. W. Hofle @ LHC Studies WG Day 2.09.2014 damper loss map 3 rd order resonance Comparison loss maps 8 Loss Maps: V. J. Moens, S. Redaelli et al. IPAC’13 MOPWO050 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

9. Impact on Tune Measurement System (LHC) W. Hofle @ LHC Studies WG Day 2.09.2014 9 with damper, max gain used less broadening with lower gain reduction of tune peak, i.e. increase residual oscillations by more than 20 dB  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 R. Steinhagen PAC’11, N.Y. feedback gain

10. BBQ hor Beam 1 amplitude damper gain hor beam 1 (linear scale) HIGH @450 GeV before prepare for ramp ramp (energy) drop of damper gain increase of damper (electronic) gain in ramp To maintain approx. same damping rate increased BBQ amplitude = more residual beam oscillations => potentially leading to blow-up; but signal needed for tune feedback which is switched on here rampprepare for ramp Injection plateau How we ran in 2011 with 50 ns beam W. Hofle @ LHC Studies WG Day 2.09.2014 10

11. ADT through the cycle - gain W. Hofle @ LHC Studies WG Day 2.09.2014 11 D. Valuch @ Evian 2011 LSA:0.25 LSA:0.02

12. evolution of beam oscillation amplitudeFast losses (BLM signal) Fast Losses with ADT Simulating “UFO” Type Losses for Quench Test W. Hofle @ LHC Studies WG Day 2.09.2014 12 1 ms IPAC’13 M. Sapinski et al. WEPME044 and THEA045 (Fast Losses and Quench Tests) Transverse Feedback was used as exciter in three quench tests carried out in February 2013

13. Shaping Time Domain Response W. Hofle @ LHC Studies WG Day 2.09.2014 13 Condition for h(nT b ) = 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

14. Performance with Bunch Trains in LHC 2012 W. Hofle @ LHC Studies WG Day 2.09.2014 14 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

15. Bunch-by-Bunch cont’d – 25 ns W. Hofle @ LHC Studies WG Day 2.09.2014 15 shortest MD: two shots August 26, 2011 [in midst of 25 ns setting-up] for 2015 G. Kotzian, ABP-HSC meeting 22.01.2014 D. Valuch et al., Evian 2014 sensitivity to internal bunch motion even odd

16. 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 16

17. Tune Measurement from ADT data - passive observation W. Hofle @ LHC Studies WG Day 2.09.2014 17 cleaning (injection) 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) time Based on recording of 6 bunches (horizontal plane) (also considering and tested excitation by short burst gated on 6 bunches) F. Dubouchet et al. IBIC’13 TUPF29

18. 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: 1 st fill: different levels of noise with ADT at constant ADT gain  measure blow-up and bunch-by-bunch lumi 2 nd 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 W. Hofle @ LHC Studies WG Day 2.09.2014 18 V. Lebedev et al. IPAC’11, MOPO013

19. W. Hofle @ LHC Studies WG Day 2.09.2014 19 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 1 st 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 Halo Cleaning using Transverse Damper (S.R.) Bench mark of blow-up equation with injected noise (W.H.) Proposed (real) MDs for 2015 Summary