Observations with the Transverse Damper at High Intensities G. Kotzian for the Damper Team BE-RF-FB, 23. February 2015LIU-SPS intermediate internal scrubbing review Feb 2015 SPS Damper - Gerd Kotzian

Outline Structure: o New Transverse Damper (pLHC & Scrub, data acquisition system) o Scrubbing Periods 2014 o Observations Beam data Damper performance 23. Feb 2015 SPS Damper - Gerd Kotzian1

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 23. Feb 2015 SPS Damper - Gerd Kotzian2

23. Feb 2015 SPS Damper - Gerd Kotzian3 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

SPS studies in Nov 2013 LBOC – Special e-cloud bunch spacing: ADT compatibility4 Old SPS damper operated at 120 MHz uses only Δ signal (un-normalized) goes unstable (phase jump) 40 MHz 80 MHz 40 MHz 80 MHz 120 MHz 160 MHz 200 MHz 120 MHz component jumps in phase by 180 o (Data from H. Bartosik, G. Iadarola, G. Rumolo) 120 MHz 160 MHz 200 MHz phase rel. to 40 MHz comp.; shift of phase of 40 MHz due to asym. splitting not displayed pLHC Scrub

New Acquisition System 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) 23. Feb 2015 SPS Damper - Gerd Kotzian5 BufferSetting BufferSelectOBS BufferAcquisition BufferSetting BufferSelectOBS BufferAcquisition in FESA3: INJECTION DAMPING (damper, chromaticity) approx. 1 ms

New Acquisition System - DIFFICULTIES o Acq Data read-out not available with double buffering  removing double buffering requires data to be transmitted in the same cycle. o Read-out of large memories blocking VME traffic(!)  interfered with the setting up of the following cycle …  data readout instantaneously (several seconds) o Buffer unwrapping not reliable  data discontinuities (systematic error) o SRAM memories suffered from setup- and hold-time violations on certain buffers  data corrupted (random error) o Data from previous acquisition  cannot reliably correlate data with other buffers/ from other sources NO AUTOSAVE  all acquisitions done manually … ( Buffers are regularly in use with settings modified during setting up) 23. Feb 2015 SPS Damper - Gerd Kotzian6

’ Data sets 23. Feb 2015 SPS Damper - Gerd Kotzian7 Week others Week pLHCScrubpLHCScrubpLHCScrub 4’060 records 69 records 2’620 records MD3MD1MD3 LHC MD4 MD3 LHC 25NS LHC PILOT 1141’5062’4402’ records no beam (41 %)(28 %)(39%)(53%)(21%)(53%) Bad wrapping Available Data: 6’749 records Analytically Valuable:2’791 data sets  drop-out ~59 % 2014 Observation Data (manually saved) 6’749 records

Observations: SCRUB module (1) 23. Feb 2015 SPS Damper - Gerd Kotzian8 VERTICALLY INSTABILE “ECHO” ≈1.8 µs Overlay of 124 turns

Observations: SCRUB module (2) LHC Pilot on SCRUB: Open Loop  BPCR.214.V 23. Feb 2015 SPS Damper - Gerd Kotzian9 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 [ ] 18:49  19: min/measurement  OPTIMIZE … ?

Observations: SCRUB module (3) 23. Feb 2015 SPS Damper - Gerd Kotzian10 CONTRAST ENHANCED! Onset time ≈1.0 µs BW ~ 1.5 MHz SPS.USER.MD1.DamperLoop_V_Scrub mat q V ~ 0.15 … to be explained!

2014 Performance - pLHC 23. Feb 2015 SPS Damper - Gerd Kotzian11 Logbook: SPS [Thursday 09-Oct-2014 Night] 00:27 HORIZONTAL VERTICAL DAMPER OFF DAMPER ON

Observations: pLHC module (1) 23. Feb 2015 SPS Damper - Gerd Kotzian12 CONTRAST ENHANCED! NO 200 MHz COMPONENT DURING SPLITTING (≈ turns) q H ~ 0.12

pLHC.MD3 - Observations 23. Feb 2015 SPS Damper - Gerd Kotzian13 Data during MD3 cycle (25ns, no splitting) Recorded: 4 th injection ms)

23. Feb 2015 SPS Damper - Gerd Kotzian14 ~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)

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) o Acquisition and Observation System improvements Improve SRAM chip timings Auto-save feature (comes with new SPS Damper UI) ObsBox  constant data flux 23. Feb 2015 SPS Damper - Gerd Kotzian15

Questions? THANK YOU!