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ADT Tune Measurement

ADT Tune Measurement. New developments and tests on August 1 st and 12 th 2012. F. Dubouchet , W. Hofle , D. Valuch Acknowledgement: R. Calaga , F. Roncarolo , E. Bravin , shift crews. ADT Tune Measurement. Reminder (Chamonix): Plan:

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ADT Tune Measurement

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  1. ADT Tune Measurement New developments and tests on August 1st and 12th 2012 F. Dubouchet, W. Hofle, D. Valuch Acknowledgement: R. Calaga, F. Roncarolo, E. Bravin, shift crews W. Hofle @LBOC 21.08.2012

  2. ADT Tune Measurement Reminder (Chamonix): Plan: implement gain modulation to selectively reduce ADT gain for witness batch (Chamonix: 12 bunches  Now: 6 bunches)done, but no improvement for BBQ situation: BBQ gating difficult, BI working on it, tests upcoming long term ADT plan: tune from residual ADT signal  massive data treatment, limitations of VME technology  not operational before LS1 as new hardware required Plan B: kick beam (witness batch) selectively by ADT and record free oscillation make an operational tool by combining with already commissioned batch by batch gain modulation use new 16384 word long dedicated study buffer on FPGA of ADT DSPU VME card method gives also the ADT damping time along the cycle  monitoring of performance W. Hofle @LBOC 21.08.2012

  3. Timeline of tests on August 1st, 2012 6 bunches, nominal intensity 1.5x1011/bunch beam measurements with 1 beam only, V-plane; both beams injected (6 bunches) using existing firmware / infrastructure (abort gap cleaning), kicking at 0.31 in tune 1: 6 turns kick (16x) 2: 3 turns kick (21x) 3: 5 turns kick (28x) 4: 5 turns kick (7x) 5: 5 turns kick (500x) 6: 5 turns kick (52x) total: 624x 5: frequency trim 6: tune trim 1 2 3 4 5 6 450 GeV, but damper gain adjusted to model situation at flat-top (damping time of 100 turns) W. Hofle @LBOC 21.08.2012

  4. Lifetime during excitation of 6 bunches start of continuous burst excitation [1 burst every 2.34 s] BLM lifetime drops from 200 hours to below 100 hours W. Hofle @LBOC 21.08.2012

  5. Lifetime cont. excitations re-started end of burst mode of 500 excitations BLM lifetime recovers after stop of excitation W. Hofle @LBOC 21.08.2012

  6. Blow-up of the 6 bunches as a result of kicks initial test (manual triggers) then 500 bursts (each 5 turns) from 13:45 to 14:05 (19.5 min) 2.34 seconds per burst td = 100 turns max amplitude 100 mm at Q7V.B1 of damper 1st period: 45 minutes, 3.3 nm / min 0.149 mm for 72 excitations + normal blow-up 2nd period: 19.5 minutes, 43.3 nm /min 43.3 nm /min  0.844 mm in 19.5 min 0.844 mm for 500 excitations + normal blow-up deduce blow-up w/o excitation (assumed to be a constant rate per unit of time): 0.65 nm/min, i.e. 29.25 nm during 1st period 12.68 nm during 2nd period  blow-up per trigger (excitation) 1st period: 72 triggers: 1.66 nm per excitation 2nd period: 500 triggers: 1.66 nm per excitation excitation bursts (approx) 500+52 72 F. Roncarolo, E. Bravin W. Hofle @LBOC 21.08.2012

  7. Tune trim (data set ‘6’) 1e-3 up and down time (hours, decimal) tune W. Hofle @LBOC 21.08.2012

  8. RF frequency trim 40 Hz up, i.e. from -20 Hz to +20 Hz with respect to central frequency of 400.788’837 MHz FGC frequency (logging on change) VCXO word 14:03:37 time [1 min / tick] W. Hofle @LBOC 21.08.2012

  9. RF frequency trim (data set ‘5’) 40 Hz up, i.e. from -20 Hz to +20 Hz with respect to central frequency 400.788’837 MHz DQ = -4.9e-4 DQ = - 4.9e-4 Dp/p = - 3.2e-4  Q’ = + 1.5 14:03:3x time (decimal) tune single bunch (!), single pick-up Q7.VB1, 2730 turns, 500 times kicked W. Hofle @LBOC 21.08.2012

  10. Data Set 5, 500 measurements, FFT average over 6 bunches 2nd peak at -20 Hz also visible for FFTs of individual bunches Real modulation of beam tune or artifact ? W. Hofle @LBOC 21.08.2012

  11. Example of a single bunch, single measurement FFT (V.B1) 20 Hz 50 Hz 2730 turns  resolution too limited to clearly resolve if there is a systematic peak at 20 Hz in the low frequency range W. Hofle @LBOC 21.08.2012

  12. Clean spectrum between 50 Hz and tune 2010 data compatible with Qsand 2Qs, fs=22.9 Hz 4.5 Hz 50 Hz tune FFT (B2.V Q7L) 2010 data 17 May 2012 damper off low bunch intensity FFT of 4 bunches (65536 turns) broad noise @20 Hz 3.5 TeV, 8 MV  fs=22.9 Hz 1 20 10 100 1000 frequency in Hz W. Hofle @LBOC 21.08.2012

  13. Data Set 5, 500 measurements x 6 bunches W. Hofle @LBOC 21.08.2012

  14. Data Set 5, 500 measurements x 6 bunches W. Hofle @LBOC 21.08.2012

  15. cut: only measurements are displayed in which upper and lower tune peaks are the highest peaks for at least one bunch average: 1.8x10-3 in tune  20.2 Hz W. Hofle @LBOC 21.08.2012

  16. 2nd test (12th August 2012) • dedicated firmware deployed (Daniel), new dedicated fesa classes (Frederic) • for excitation similar to AGC, but “skimmed down” • excitation scales automatically with normalised damper gain • dedicated parameters and resources: • window (gating on part of the beam) • DDS to generate excitation with programmable excitation frequency • number of kicks (in turns) • dedicated memory on FPGA (16384 bunch x turns) •  max 2730 turns for each of the 6 bunches kicked • beam test (12th August 2012) • injected 2x6 bunches per beam with standard, i.e. minimal possible spacing • symmetric pattern with collisions in IP1 and IP5 only (bucket 1 and 651) • use first 6 as witness bunches, kicked by ADT, 4 planes x beams • kicked every beam and plane once per 4 seconds • (rotating kicks every second between beam and plane) • 4 turns kicked at 0.28 (H) and 0.31 (V), amplitude 0.8 of max no changes to operational Parameters and functions  real life W. Hofle @LBOC 21.08.2012

  17. ramp Beam modes: 19:33 prep4ramp 19:37 ramp 19:50 F-top 20:15 squeeze 20:39 adjust 21:26 dump Damping times collisions flat top and squeeze injection Fill 2956 Daniel’s tool W. Hofle @LBOC 21.08.2012

  18. Horizontal Beam 1 collisions with S / p modes • flat bottom • high ADT gain • need lower • ADT gain • for the first 6 tune change at start of squeeze ramp Fill 2956 Beam modes: 19:33 prep4ramp 19:37 ramp 19:50 F-top 20:15 squeeze 20:39 adjust 21:26 dump setting-up then refill FFTs from 6 bunches averaged W. Hofle @LBOC 21.08.2012

  19. Horizontal Beam 2 FFTs from 6 bunches averaged collisions • flat bottom • high ADT gain • need lower • ADT gain • for the first 6 spurious at 0.3068 n x frev +/- 3450 Hz messes up spectrum  need to kick harder Fill 2956 Beam modes: 19:33 prep4ramp 19:37 ramp 19:50 F-top 20:15 squeeze 20:39 adjust 21:26 dump spurious ramp: tune took a dive due to tune FB locking on wrong line switched off and corrected at FT setting-up then refill W. Hofle @LBOC 21.08.2012

  20. Vertical beam 1 FFTs from 6 bunches averaged collisions flat top spurious messes up spectrum  need to kick harder Fill 2956 Beam modes: 19:33 prep4ramp 19:37 ramp 19:50 F-top 20:15 squeeze 20:39 adjust 21:26 dump W. Hofle @LBOC 21.08.2012

  21. Vertical Beam 2 FFTs from 6 bunches averaged collisions flat top with spurious messes up spectrum  need to kick harder Fill 2956 Beam modes: 19:33 prep4ramp 19:37 ramp 19:50 F-top 20:15 squeeze 20:39 adjust 21:26 dump W. Hofle @LBOC 21.08.2012

  22. Individual bunches 20 Hz line moves with beam tune ! W. Hofle @LBOC 21.08.2012

  23. Individual bunches 20 Hz line moves with beam tune ! W. Hofle @LBOC 21.08.2012

  24. Emittance blow-up F. Roncarolo, E. Bravin W. Hofle @LBOC 21.08.2012

  25. Emittance blow-up F. Roncarolo, E. Bravin W. Hofle @LBOC 21.08.2012

  26. Emittance blow-up F. Roncarolo, E. Bravin W. Hofle @LBOC 21.08.2012

  27. Emittance blow-up F. Roncarolo, E. Bravin W. Hofle @LBOC 21.08.2012

  28. Towards making an operational tool – next steps • implement control of parameters in sequencer, plus start / stop functionality (t.b.d.) • implement FFTs in front-end (0.45 ms/FFT, 12 FFT  5.4 ms (6 bunches, 2 PU) • average FFTs in front-end  publish averaged FFT and tune (peak), fitting (?) • make operational with 1374 bunches once sequencer work completed, and • acquisition working • explore parameter space to get desired resolution • understand and decide how to deal with the spurious 20 Hz line next to the tune (!) • needs: gain modulation programmed to tailor damping time of the 6 bunches • kicking harder at flat top when spurious lines perturb • (kicking to larger amplitudes by increasing the number of turns kicked or by increasing normalised gain + additional gain modulation to • maintain same gain for main beam) • suggestion: use more turns of excitation when amplitude is insufficient and • flat-bottom: gain modulation 16/128 for the 6, 127/128 for rest • ramp / flat-top / squeeze: gain modulation 64/128 for the 6, 127/128 for rest W. Hofle @LBOC 21.08.2012

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