1. Design and Performance of the Upgraded SPS Damper after LS1 G. Kotzian for the Damper Team BE-RF-FB, 13. February 2015MSWG https://indico.cern.ch/event/367094/ 13. Feb 2015 SPS Damper - Gerd Kotzian0 Acknowledgements: BE-RF-FB, BE-RF-CS, BE-RF-PM, BE-BI, BE-OP, BE-ABP, TN-EL

2. Transverse Damper in General  The transverse damper is a feedback system: it measures the bunch-by- bunch oscillations and damps them by fast electrostatic kickers.  Key elements:  Beam position monitor(s)  Signal processing system  Power amplifiers  Electrostatic kickers  Key parameters:  Feedback loop gain, phase, and total loop delay  Kick strength  System bandwidth 1 D. Valuch, “TRANSVERSE FEEDBACK: HIGH INTENSITY OPERATION, ABORT GAP CLEANING, INJECTION GAP CLEANING AND LESSONS FOR 2012”, in LHC Beam Operations Workshop, Evian 2011. 13. Feb 2015 SPS Damper - Gerd Kotzian

3. Outline Objective: Have a look at the upgraded SPS Damper and its internal structure, to gain insight in what/how the damper can be used e.g. for MDs. Structure: o Design of the upgraded SPS Damper o 2014 Performance o Outlook for 2015 13. Feb 2015 SPS Damper - Gerd Kotzian2 Damper, not Dumper

4. Former SPS Transverse Feedback System o Last upgrade 1997-2000 in preparation of the SPS as LHC injector o damping of injection errors and cure of resistive wall impedance driven coupled bunch instability (threshold ~5x10 12 protons total intensity) o operates since 2001 between lowest betatron frequency and 20 MHz (V & H plane) to damp all possible coupled bunch modes at 25 ns bunch spacing o handles large injection errors of the order of several mm o Tetrode amplifiers with two tubes drives kicker plates in push-pull configuration installed in tunnel under kicker, 200 W drive power per tetrode, 3 kHz to 20 MHz o Technology of electronics of system used in SPS until 2012 dates from late 1990’s 13. Feb 2015 SPS Damper - Gerd Kotzian3

5. Scope and Motivation for SPS damper upgrade under LIU Why LS1? sharing pick-ups with Orbit System (MOPOS) from Beam Instrumentation Group incompatible with MOPOS upgrade requirements for single bunch damping for protons used for LHC p-ion Physics (closer spaced proton bunches, 100 ns) ions injection damping with fixed frequency scheme, closer spaced batches individual bunch damping for crab cavity studies not possible with previous system (sampling was not synchronous with bunch in previous system) LHC doublet scrubbing beam incompatible with previous system controls with G64 chassis and MIL-1553 (a.k.a. MMI) became obsolete  new controls for power system and LLRF, new RF function generators 13. Feb 2015 SPS Damper - Gerd Kotzian4

6. 13. Feb 2015 SPS Damper - Gerd Kotzian5 PU1 BEAM BPM Proc. PU2 BPM Proc. BPM Proc. BPM Proc. KICKER1 PLC1PLC2 200 W Driver 200 W Driver Final Stage Final Stage Electrostatic PU processing BW ~100MHz Stripline pickup processing pLHC, Scrub Ions pFT Damper Signal Selector Damper Power System KICKER2 Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 ADC2 DAC1 DAC2 Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 ADC2 DAC1 DAC2 Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 ADC2 DAC1 DAC2 Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 ADC2 DAC1 DAC2 SPS Damper Loops pLHC SPS Damper Loops pFT SPS Damper Loops Ions SPS Damper Loops Scrub from BBQ from VNA Baseband Frontend (40 MHz) RF Frontend 200 MHz FSK Baseband Frontend RF Frontend 200 MHz Switch M1 Switch M2 pLHC pFT Ions Scrub SURFACE BA2 TUNNEL LSS2 cfv-ba2-alltrdamp[hv]1 cfv-ba2-alltrdamp[hv]2

7. 13. Feb 2015 SPS Damper - Gerd Kotzian6 PU1 BEAM BPM Proc. PU2 BPM Proc. BPM Proc. BPM Proc. Electrostatic PU processing BW ~100MHz Stripline pickup processing Damper Signal Selector Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 Baseband Frontend (40 MHz) ADC2 DAC1 DAC2 Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 RF Frontend 200 MHz FSK ADC2 DAC1 DAC2 Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 Baseband Frontend ADC2 DAC1 DAC2 Beam Pos1 Beam Pos2 DSPU 1 DSPU 2 ADC1 RF Frontend 200 MHz ADC2 DAC1 DAC2 from BBQ Switch M1 Switch M2 pLHC pFT Ions Scrub from VNA SURFACE BA2 TUNNEL LSS2 pLHC, Scrub Ions pFT KICKER1 PLC1PLC2 200 W Driver 200 W Driver Final Stage Final Stage Damper Power System KICKER2 SPS Damper Loops pLHC SPS Damper Loops pFT SPS Damper Loops Ions SPS Damper Loops Scrub cfv-ba2-alltrdamp[hv]1 cfv-ba2-alltrdamp[hv]2

8. Power System Consolidated 13. Feb 2015 SPS Damper - Gerd Kotzian7 Tetrode amplifier in SPS LSS2EM field simulation of kicker new process control based on PLC in BA2  FESA remotely accessible

9. 6x Beam Position Monitors installed in LS1 13. Feb 2015 SPS Damper - Gerd Kotzian8 BPCR.221 all BPMs re-cabled with 7/8-inch smooth wall coaxial cables during LS1; [length ~250..700m] BPH/BPV: electronics and amplifiers in the tunnel tested and verified; "hot-spares" readily checked and kept in the tunnel BDH / BDV kickers unchanged RF Faraday cage SPS Transverse FB 2 BPCR (H/V) for LHC type beams (couplers maximum Z T @ 200 MHz) 2 BPH electrostatic PU (pFT) 2 BPV electrostatic PU (pFT) DeviceDelay BPH.2022.48 μs BPH.2042.24 μs BPV.2052.12 μs BPV.2071.88 μs DeviceDelay BPCR.2140.97 μs BPCR.2210.82 μs H1/H2/V11.57 μs V21.31 μs Approximate transport delays:

10. Analog Frontend Control / External Control o External control (only LHC type beams): disable 50 Ohm input termination disable attenuation enable amplifier o Two analog frontend types: RF frontend, used for pLHC and Ions, LO = 200 MHz, I/Q components Baseband frontend (BB), used for pFT and Scrub, only I-component o Input gain control: RF: switching attenuators + amp, delay matched dynamic range: -29 dB to + 10 dB. BB: variable gain amplifier (VGA) dynamic range: -27.4 dB to + 26 dB. o Frontend protection circuitry input overdrive protection: fast enables all attenuators, disables all amplifiers no recovery  cycle is lost! reports as ALARM in LASER ; action required! o ADC overflows (8x) report as WARNINGS in LASER 13. Feb 2015 SPS Damper - Gerd Kotzian9 LO 200 MHz 120 MHz RF frontend schematic FEBbGain FERfGAIN FESelect FEBbGain FERfGAIN FESelect in LSA 

11. Beam Position Block (BeamPos) o 2 BeamPos Blocks per damper loops module = one per pick-up input o I/Q inputs of SUM and DELTA signals in ADC sampling clock domain, hence subject to delay adjustment o CoRe – Conditioning and Resampling I/Q phase rotation Down sampling: 120 MSPS  40 MSPS (25ns bunch sync) o Clock domain crossing from 2x ADC input clocks (delayed per pick-up) to synchronous reference clock (undelayed) o Normalization position calculation (in-phase) “quadrature position” indicating head-tail activity bypass mode in case of DELTA processing (pFT) o Overflows (Sum, Delta, Norm) report as WARNINGS in LASER 13. Feb 2015 SPS Damper - Gerd Kotzian10 BeamPos1PpmCtrl BeamPos2PpmCtrl SwitchControl BeamPos1PpmCtrl BeamPos2PpmCtrl SwitchControl in LSA

12. Sensitivity of Frontend to intrabunch motion (LHC ADT) 22. Jan 2014 Sensitivity of LHC ADT to intra-bunch motion11  indication of odd-mode oscillations!  re-evaluate for SPS case Symmetric (even mode) ExcitationAnti-symmetric (odd mode) Excitation NB: although higher even modes visible the damper is acting only in baseband up to 20 MHz – for damping of higher frequencies  wideband transverse feedback 13. Feb 2015 SPS Damper - Gerd Kotzian

13. Visualization of Bunch Motion 13. Feb 2015 SPS Damper - Gerd Kotzian12 Rapid identification of quiet bunches bunches with transverse center of mass motion bunches with head tail motion bunches with combination of center of mass and headtail motion with correlation Example: LHC run 2012 I DELTA Q DELTA

14. DSPU – Digital Signal Processing Unit o 2 DSPUs per damper; one per module; two inputs o Signal processing Notch filter Hilbert phase shifter / PU vector sum Bunch masking phase equalizer FIR (up to 64 taps), linearize phase of power system ≈ low pass 1 st order, cutoff freq. (-3dB) @ 4.5 MHz operated at 40 MSPS  better resolution at lower frequencies gain equalizer (up to 64 taps), digital low pass shaping output signal operated at 120 MSPS o Clock domain crossing upsampling: 40 MSPS  120 MSPS (Interpolated by gain equalizer = LP FIR) from synchronous reference clock (undelayed) to 2x DAC output clocks (delayed)  implements actual 1-turn delay o Switches NotchEnable, PhaseShiftEna, Ch1/Ch2 enable, Loop/Aux enable, Digital Loop Enable o Overflows report as WARNINGS in LASER 13. Feb 2015 SPS Damper - Gerd Kotzian13 phase equalizer FIR, comp. 1 st order 4.5 MHz digital low pass, fc ≈ 16 MHz DSPU[1,2]EqControl DSPU[1,2]Mask DSPU[1,2]SwitchCtrl DSPU[1,2]EqControl DSPU[1,2]Mask DSPU[1,2]SwitchCtrl in LSA:

15. DSPU – Digital Signal Processing Unit 13. Feb 2015 SPS Damper - Gerd Kotzian14 Functions (from RFFG) - in LSA: Control signals (FESA) – in LSA: Excitation input (DDS) DSPU[1,2]EqControl DSPU[1,2]Mask DSPU[1,2]SwitchCtrl DSPU[1,2]EqControl DSPU[1,2]Mask DSPU[1,2]SwitchCtrl FGCPpmControl LoopsControl Use Digital Loop Switches  preferred way to disable damper

16. Default Timings o RT task (PPM READ/WRITE) o 120 MHz resync (200 ms before INJ) o fRev resync (flywheels in 5 clock domains) o start function generation (RFFG) o close damper loops H1/H2 resp. V1/V2 before injection o scope trigger, o VNA trigger, o observation trigger + MEM readout task o open damper loops Loop Control: o Use Digital Loop Switches (preferred way to disable damper) o Loop ON & OFF timings are required to ensure proper behaviour  do not disable 13. Feb 2015 SPS Damper - Gerd Kotzian15 LoopsControl in LSA:

17. Clock Distribution: fRF and fREV o new fiber optic links between Faraday cage in BA3 and Damper racks in BA2 new fibers installed during LS1 VME FO modules (RX/TX) status + diagnostics available (FESA) o local clock distribution in BA2 active splitting (NIM modules) o local clock generation 120 MHz out of 200 MHz fRF beam synchronous, for sampling ADCs and DACs resync once per cycle to fREV before injection o fREV resynchronization 5 clock domains (SynClk, ADC1, ADC2, DAC1, DAC2) one flywheel per clock domain, resync once per cycle to fREV before injection o Monitoring possibilities  no Alarms (ion cycle does not transmit fRF all the time) 13. Feb 2015 SPS Damper - Gerd Kotzian16 expect over year 20 degrees drift @200MHz 1.9 km fiber links long-term measurement Winter  Summer CLOCKControl CLOCKPpmControl CLOCKControl CLOCKPpmControl in LSA:

18. Closed loop delay compensation 13. Feb 2015 SPS Damper - Gerd Kotzian17

19. Functions Distribution o 3 RFFGs: Horizontal / Vertical / eXperimental 32bit Serial Control Link, 16bit payload (32bit optional) 1ms update rate (up to 16 kHz) o 16 functions (PPM): gain, phase, PU mixing coeffs, delay daisy-chained through all 4 damper modules via the backplane: RFFG  pFT  pLHC  Scrub  Ions  RFFG only 1 module active (ACK) at a time, frames return as NACK if no module is active tricky if 2 or more modules active at the same time (must be avoided) static value output vs. functions (LSA selectable) o Frontpanel serial links (16bit) 4x setpoint values to Power Converters send as hexadecimal numbers: 0x4300 == 4.3 kV voltages out of range will trip the power system  EXPERT SETTING care must be taken when power cycling these crates: cfv-ba2-alltrdamph1, cfv-ba2-alltrdampv1, if in doubt set power system first to LEVEL1 13. Feb 2015 SPS Damper - Gerd Kotzian18 FGCPpmControl in LSA: ALLRfFuncGen/ FPSLStaticValues ALLRfFuncGen/ FPSLStaticValues in LSA: ALLRfFuncGen/ Functions ALLRfFuncGen/ Functions in LSA:

20. Damper Signal Selector (DSS) o 2 DSS (H/V), with 2 fully independent channels, to select between inputs Module1 and Module2 o 4 + 1 + 1 + 1 loop inputs per output 4 damper modules (pLHC, pFT, Ions, Scrub) 1 eXperimental module for developments and MDs (Xper) 1 transverse excitation input (BBQ  Marek Gasior) 1 external VNA input o selectable VNA output allows for open loop TF measurements allows for closed loop TF measurements measure one plane, i.e. both modules and pick-ups with one VNA setup + remote controllable switching 13. Feb 2015 SPS Damper - Gerd Kotzian19 ALLDampSigSel/ SwitchPPMControl ALLDampSigSel/ SwitchPPMControl in LSA: Logbook: SPS [Thursday 09-Oct-2014 Night] 00:27 Damper commissioning and setting-up for LHC beam on MD1: parameters for all 4 dampers H1/H2/V1/V2 adjusted. Fine- delay for pick-ups 214 and 221 in H/V determined using the beam transfer function measurement. Input dynamic range adjusted based on +/-5mm bumps and nominal per bunch intensity (1.15e11 ppb, 48 bunches). Today, for the very first time, the system was set-up completely remotely from the CCC.

21. Acquisition and Observation o provide means to expert users/piquets for diagnostics triggered by timing  freezes acquisition buffers in all channels 7 Channels, (16 buffers) − 1 OBS channel (4 buffers, selectable sources) − 6 channels per clock domain (2 buffers each, dedicated) o OBS data sources available I/Q data for sum/delta inputs (per pick-up) position data (+head-tail component) probe various DSPU internal signals 40 MSPS, 4 buffers, each 2MSamples, or ~ 2000 turns o Dedicated channels: 120 MSPS 2 buffers per channel, each 4095 samples 1-turn data (2772 slices) per ADC and DAC channel adjustment of sampling delay clock tagging (bunch 0) NB: constant data stream available (in the future)  ObsBox! (LMC March 13 th 2015) 13. Feb 2015 SPS Damper - Gerd Kotzian20 BufferSetting BufferSelectOBS BufferAcquisition BufferSetting BufferSelectOBS BufferAcquisition in FESA3: INJECTION DAMPING (damper, chromaticity) approx. 1 ms

22. 2014 Performance - pFT 13. Feb 2015 SPS Damper - Gerd Kotzian21 SUM DELTA [18.9.2014] Injection of fixed target proton beam Intensity about 10-20% of nominal more charges towards the end of the batch oscillating in HORIZONTAL

23. 2014 Performance - pFT 13. Feb 2015 SPS Damper - Gerd Kotzian22 LEGEND: YELLOW delta signal pickup 202; BLUE kick voltage module 1; GREEN kick voltage module 2 Logbook: [Monday 27-Oct-2014, 23:15] HORIZONTAL VERTICAL VNA HORIZONTAL 3MHZ VNA VERTICAL 3MHZ approx. 0.7 ms 1 ms RECOHERENCE open loop BTF measurement sweep of two betatron lines adjustments using phase setting and loop delay synchrotron sidebands seen

24. LHC25ns beam as seen by pFT 13. Feb 2015 SPS Damper - Gerd Kotzian23 [18.9.2014] Injected batch of 12 LHC bunches, spaced by 25ns, intensity about 1.1x1011 ppb. Saturation phenomena develops 10 turns after the injection. [19.9.2014] The effect comes from an electron cloud and the amplifiers handle it with no problems. It runs like this since 2008. SUM DELTA

25. 2014 Performance - pLHC 13. Feb 2015 SPS Damper - Gerd Kotzian24 Logbook: SPS [Thursday 09-Oct-2014 Night] 00:27 HORIZONTAL VERTICAL DAMPER OFF DAMPER ON

26. LHC Pilot Setting Up: Open Loop  BPCR.214.V 13. Feb 2015 SPS Damper - Gerd Kotzian25 o OL-Ver 100 kHZ o OL-Ver 1 MHZ o OL-Ver 2 MHZ o OL-Ver 4 MHZ o OL-Ver 6 MHZ o OL-Ver 10 MHZ [07.12.2014] 18:49  19:35 5-10 min/measurement  OPTIMIZE … ?

27. pLHC.MD3 - Observations 13. Feb 2015 SPS Damper - Gerd Kotzian26 Data during MD3 cycle (25ns, no splitting) Recorded: 4 th injection (@ 10800 ms)

28. 13. Feb 2015 SPS Damper - Gerd Kotzian27 ~70 turns 1 turn 1 st batch2 st batch3 rd batch4 th batch activity in the last injected batch (+1 st order roll-off of damper gain)

29. Status End 2014 o Completely new system built and taken into operation (March – Dec) o Commissioning challenges: Issue with pFT  isolation transformers of all PU inputs had polarity swapped FESA3 class  on-the-fly bug-fixing at the time no high-level software … all setting-up done in FESA All sorts of troubles with the internal observation system … “… driving your car with windows painted black – you have to get off to see if your lights are on!” Setting up of feedback parameters requires stable beam conditions (here I’m not referring to “stable beam”); [tune, chromaticity, injection timing, bucket selection, … ] Damper switched OFF by CCC while we were setting up things in BA2 …?!! …  communication issue 13. Feb 2015 SPS Damper - Gerd Kotzian28

30. Outlook for 2015 – SCRUBBING o Evaluate scrubbing module  Investigate on “phase behaviour” compare Scrub vs. pLHC sharing same PU and same power system, expect same behaviour … o Move to full I/Q signal processing currently the scrubbing module is too sensitive to sampling delay implement in analog, requires modification of HW  DDC - digital down conversion, modification of FW o run Scrub + pLHC damper in parallel Scrub active during splitting process (40 MHz present) pLHC kicks in once splitting is complete (200 MHz restored) 13. Feb 2015 SPS Damper - Gerd Kotzian29 “PU signal” single bunchdoublet 200 MHz BP filtered 40 MHz BP filtered (120 MHz sampled) Analog signals before digitization: 25 ns spaced doublets (during LAB testing)

31. Outlook for 2015 – USER INTERFACE o refactoring damper loops FESA class V2.0 firmware: excess functionality removed (mainly housekeeping, no change in signal processing!) testing using the Xperimental crate, no impact on operations (yet) o make LSA consistent with new FESA class adding value generators, for cycle generation  definition of “safe settings” value generation for timing knobs declare make rules for functions, in particular delay/gain o GUI in JAVA talks to LSA (set parameters) and FESA (read back) loads settings to LSA for 1 active damper (sets others to “safe settings”) configure ACQ and fetch OBS data from FESA display status and monitoring (frequencies, voltages, and power levels) trimming of feedback parameters (in LSA, with history) store/recall reference settings import/export damper settings to file (consistent snapshot, e.g. for/during MDs) 13. Feb 2015 SPS Damper - Gerd Kotzian30 “RESTORE TO DEFAULT SETTINGS” Kick-off meeting: 18.Feb 2015, 14 30 in the CCC

32. Outlook for 2015 - AOBs o OASIS signals route essential signals to remote samplers o Logging Have damper parameters also stored in the MDB + LDB Facilitate data retrieval, plotting of e.g. switch statuses o Prepare for ObsBox (  see LMC on March 13 th 2015) SFP cages per damper module install local PCs in BA2 requires software for the number crunching o Loop gain tracking from 14 GeV/c @ INJ to 450 GeV/c @ FT need to increase loop gain by factor 32.14, or 30 dB, through the ramp analog vs. digital gain (noise issue? limit drive signal?) 13. Feb 2015 SPS Damper - Gerd Kotzian31

33. Outlook for 2015 - MDs MD requests aim on evaluating concepts for improvements of the damping performance − different implementations for phase shift filters − adaptive feedback control − test a novel damping algorithm − bunch extrapolation (single bunches, ions), beam gap interpolation (in between batches) develop methods to facilitate loop diagnostics − loop information indispensable during commissioning and for setting-up − easy-to-use repeatable measurements: allows re-qualification of settings/parameters  handy e.g. for cycle generation − review potential for per-bunch head/tail activity monitoring (test with wideband feedback) exploitation of new features − real bunch-by-bunch damper (in view of crab cavity tests) − adding a DDS allows for built-in-network analysis − controlled emittance blow-up, beam cleaning, and bunch shaping using transverse excitation signals 13. Feb 2015 SPS Damper - Gerd Kotzian32

34. 13. Feb 2015 SPS Damper - Gerd Kotzian33 Questions? THANK YOU!

35. MD8 – Semi-automated feedback parameter extraction Objective: extract loop parameters by means of automated measurements o basis is the classical method with VNA(s) o automate repeated measurements by means of scripting adding remote control for VNA(s) automatic data collection requires interfacing with damper loops, i.e. signal switching o extract parameters from multiple measurements closed loop feedback parameters: phase (Hilbert phase shifter, PU mixing coefficients) and delay (coarse and fine delay) but also parameters such as phase and gain equalization, betatron tune, (synchrotron tune) o Once implemented and proven to work: this method shall speed up a great deal the setting up allows re-qualification of settings/parameters scripting could be used compare parameters with LSA settings, and possibly feed back new values o Measurements done with calibrated VNA(s)  serve as reference for other methods/input required for further MDs 13. Feb 2015 SPS Damper - Gerd Kotzian34

36. MD9 – Feedback performance evaluation with different phase shift filters Objective: study different implementations of phase shift filters o original idea for LHC o further developed for Q20 optics, in view of wide band feedback o goal: make feedback phase insensitive to tune variations 13. Feb 2015 SPS Damper - Gerd Kotzian35 Phase compensation for sidebands Notch, 1T delay, phase rotation

37. MD10 – Injection damping using adaptive feedback control Objective: extract knowledge of per-bunch oscillation amplitude, and boost gain for individual bunches 13. Feb 2015 SPS Damper - Gerd Kotzian36 MD11 – Test a novel damping algorithm Objective: extract knowledge of per-bunch oscillation phase, and modulate kick for individual bunches

38. MD12 – Real bunch-by-bunch damper based on feedback gain equalization Objective: shaping the time-domain response to generate individual kicks per-bunch, requires feedback gain equalization/gain levelling o LHC case  see W. Hofle, “PERFORMANCE OF THE LHC TRANSVERSE DAMPER WITH BUNCH TRAINS,” WEPME043 - IPAC’13. o Useful for crab cavity tests o Individual bunch blow-up (in coast) o Fully linearized system 13. Feb 2015 SPS Damper - Gerd Kotzian37 LHC ADT

39. MD13 – Feedback operation powered by built-in VNA Objective: achieve same results as MD8 with all-built-in mechanisms (VNA) o analyze 2 or more pick-up signals at once 50% of the time (2 pick-ups in the SPS) ¼ of the time in case of LHC (ultimately 4 pick-ups) o Same interface to data and parameters as for the damper loops no external instrument required (SW maintenance, Windows PC) valid for operational use with gain equalization, i.e. fully linearized system  BTF 13. Feb 2015 SPS Damper - Gerd Kotzian38 MD14 – Controlled emittance blowup, beam cleaning, and bunch shaping using transverse excitation signals Objective: use results from MD13, i.e. the DDS, and noise generators to inject transverse excitation signals for beam manipulations o aim: have transverse excitations available for MDs

40. MD15 – Frontend noise evaluation Objective: Evaluate the frontend performance and its sensitivity to low-amplitude transverse beam signals o Key word: dithering  intentionally apply signal to randomize quantization error 13. Feb 2015 SPS Damper - Gerd Kotzian39 MD16 – On the analysis of feedback stability by increasing the frontend gain after injection damping and during acceleration Objective: Evaluate the loop stability after increasing the frontend gain and once large oscillation amplitudes have been damped.

41. MD17 – Performance evaluation using bunch extrapolation/beam gap interpolation Objective: enhance kick strength for single bunches (iones) and possibly at the tails of batches/trains o issue: full kick strength only available for frequencies up to < 5 MHz o Proposed solution: peak hold 13. Feb 2015 SPS Damper - Gerd Kotzian40 MD19 – A different means to determine correct delay adjustment Objective: Application of different excitation patterns and subsequent correlation to extract delay information. o Pulse excitation + damping (less destructive) o Modulated sinusoidal (for higher frequencies) o Wavelets + correlation Dense spacing 100 nsTruly isolated bunches 250 ns scheme for large spacing