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Commissioning of the FPGA-Based Transverse and Longitudinal Bunch-by-Bunch Feedback System for Taiwan Light Source Kuo-Tung Hsu on behalf of the feedback.

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Presentation on theme: "Commissioning of the FPGA-Based Transverse and Longitudinal Bunch-by-Bunch Feedback System for Taiwan Light Source Kuo-Tung Hsu on behalf of the feedback."— Presentation transcript:

1 Commissioning of the FPGA-Based Transverse and Longitudinal Bunch-by-Bunch Feedback System for Taiwan Light Source Kuo-Tung Hsu on behalf of the feedback team NSRRC Hsinchu 30076, Taiwan May 2, 2006 BIW06, FNAL, May 1~4, 2006

2 I.Introduction II.Feedback Processor III.Transverse Feedback System IV.Longitudinal Feedback System V.Summary Outline BIW06, FNAL, May 1~4, 2006

3 I. Introduction TLS is a 1.5 GeV light source. Dedication in October 1993. Instabilities are severe in the operation of last decade. SRF upgrade in Dec. 2004. Routine top-up operation is started from Oct. 2005. FPGA-based transverse and longitudinal feedback system are deployed in Dec. 2005 and Feb. 2006. BIW06, FNAL, May 1~4, 2006

4 II. FPGA Based Feedback Processor Adopted form the design of SPring-8. Minor modification in FPGA code. USB 2.0 interface is supported. Up to 20 taps FIR filter is supported for transverse feedback. Up to 50 taps FIR filter is supported for longitudinal feedback. Up to 10 (20) decimation factor is supported. => only useful for longitudinal feedback. BIW06, FNAL, May 1~4, 2006

5 DDR F/F 12 Bit Delay FIFO X 4 PLL 499.65 MHz 4:1 MUX Delay FIFO x2 to 249.83 MHz 4:1 MUX 4:1 MUX Delay Adj. DDR SDRAM, 128 Mega Samples f RF /4 = 124.91 MHz DAC 500 MS/sec ADC 125 MS/sec FPGA: Xilinx VirtexII Pro XC2VP70-6FF1517C FIR Filter* FIFO 12 Bit 50-tap FIR Filter 20-tap FIR Filter FIR Filter* FIFO 12 Bit FIR Filter* FIFO 12 Bit FIR Filter* FIFO 12 Bit Structure of the Feedback Processor BIW06, FNAL, May 1~4, 2006

6 Feedback Processor Bunch Oscillation Detector Back-end Electronic and Power Amplifiers USB 2.0 Interface => Register access => Memory access Control Network Linux/PC : * Feedback Processor Linux Driver support USB 2.0 access * Matlab interface Control database interface Feedback processor register access Captured bunch oscillation data access Feedback filter design Data analysis * Control console Linux (CentOS Distribution) Transverse Kicker Transverse and Longitudinal Pickup Longitudinal Kicker Feedback System Environment BIW06, FNAL, May 1~4, 2006

7 III. Transverse Feedback System 1995 Commissioning of the analog feedback system. * Only vertical instability is a problem. * Longitudinal instability is severe. 1996 Second tuner was introduced to RF cavities to shift HOM frequency. * Longitudinal instability is still severe. * Transverse instability can be controlled by optimized position of the second tuner. 2004.12 SRF put into operation. * Both horizontal and vertical instability are strong. * Difficult control by over compensated chromaticity. 2005.04Analog transverse feedback loop is put back into service again * Both plane instability was suppressed, however, tune dependence is strong. It is not easy to operate the machine with 0.1% flux stability. BIW06, FNAL, May 1~4, 2006

8 2005.10.12 Start top-up operation @ 200 mA 2005.11.29 Commissioning of the new transverse feedback system. * To solve the sensitivity problem of tune dependence. * To provide better damping for high current operation. * Increase injection efficiency by reduce chromaticity. => High injection efficiency is essential for top-up operation. 2005.11.30 New digital transverse feedback system commissioning and put into service immediately. 2005.12Start top-up operation at 300 mA BIW06, FNAL, May 1~4, 2006

9 Divider A B C D ADC 20tapFIR ADC 20tapFIR DACs BBF Clock Generator Clock/4 = 124.913 MHz Clock/4 = 124.913 MHz Divider # A # B FPGA Clock 124.913 MHz f RF 499.654 MHz 250 W AR 250A250 10 KHz ~ 250 MHz Transverse Kicker 2 ns D 20 dB 53 dB 20 dB 156 MHz LPF Block Diagram of the New Transverse Feedback System 2 V p-p LVDS 933 MHz LPF B D Feedback Processor ch 1 ch 3 ch 2 ch 4 4 ns 20 dB 46 dB LNA X 4 # 1, 5, 9,.. 197 # 3, 7, 11,.. 199 # 2, 6, 10,.. 198 # 4, 8, 12,.. 200 BIW06, FNAL, May 1~4, 2006

10 Target Working Point ( x, y ) = (7.312, 4.168) Tunability ~ 0.05 C = 120 m T rev = 400.2 ns F rev = 2.49827 MHz Location x (m) y (m) x y x (m) R5 BPM1 11.3 5.4 4.876 3.018 0.033 R5 Kicker 4.5 2.7 5.572 3.232 0.397 R5 R4 R3 R2 R1 R6 Feedback Electronics 80 nsec 150 nsec R5BPM1 (B - D) Kicker (B - D) Layout of pickup & kicker BIW06, FNAL, May 1~4, 2006

11 Response of the Prototype FIR Filter ParameterValue Energy, E1.5 GeV RF frequency, f RF 499.654 MHz Harmonic number, h200 Revolution frequency, f rev 2.49827 MHz Momentum compaction factor 0.00067 Operating current, I B 302 mA (March 2006) Betatron frequency, f x /f y ~ 760 kHz / 450 kHz Betatron tune, x / y ~ 0.31 / 0.17 Down-sampling factor, D1 Bunch sampling frequencyf rev = 2.49827 MHz Working frequency of the betatron oscillation detector f RF Taps of feedback FIR filter up to 20 Parameters of the Transverse Feedback System Target Tune Working tune bandwidth (change in arbitrary way) x : 716 kHz ~ 822 kHz (7.285 ~ 7.328) => > 0.04 y : 400 kHz ~ 480 kHz (4.16 ~ 4.192) => > 0.03 Negative chromaticity Nominal setting (SF, SD) = (151 Amp, 124 Amp) => (SF, SD) = (121 Amp, 114 Amp) => Beam is still stable => (SF, SD) = (100 Amp, 100 Amp) => Beam is still stable However, beam loss suddenly when turn off the feedback loop Feedback Loop Tunability BIW06, FNAL, May 1~4, 2006

12 Beam spectrum observation – Feedback OFF and ON Beam spectrum observation (without longitudinal feedback) Feedback OFF Feedback ON BIW06, FNAL, May 1~4, 2006

13 Loop Closed Loop Open Snapshot of Synchrotron Radiation Beam Profile (w/o Longitudinal Feedback) Grow/Damp test results @ 300 mA Horizontal Vertical Horizontal Modal Spectrum BIW06, FNAL, May 1~4, 2006

14 Stable operation have been achieved in users shift. Better than 10 -3 photon flux stability can be achieved routinely. Various feedback filters will be tested in a short- term to probe the possibility to improve system performance. Improve various components form operation point of views are under way. Current Status of the Transverse Feedback System BIW06, FNAL, May 1~4, 2006

15 IV. Longitudinal Feedback System Longitudinal instability is serve during last decade operation of TLS. Optimized the second tuner position and RF gap voltage modulation is the tools to deal this instability with the cost of large energy oscillation. After SRF upgrade Strength of the longitudinal is weaker than before. Mode pattern are much simple. Longitudinal feedback system are used to lift the residue instabilities. 2006.01New longitudinal kicker installed. 2006.02.06 Longitudinal feedback system commissioning. BIW06, FNAL, May 1~4, 2006

16 Summary of Measured Longitudinal Kicker Performance Modified from the DAΦNE and BESSY kickers (four ridged waveguide damper; nose cone) Center frequency @ 1375 MHz, BW > 250 MHz Highest shunt impedance ~ 1500 A few higher order modes are trapped in the structure and are damped by a hybrid TE/TM coupler Successful operation of the SLS longitudinal kicker Easy adaptation to the TLS storage ring with minor modifications (nearly rectangular 28 x 88 mm beam pipe elliptical, 38 x 80 mm beam pipe) Variation of group delay across the operation bandwidth found (~ 600 ps) Symmetrical excitation to minimize transverse kick due to field non-uniformity Adaptation of the SLS Longitudinal Kicker to the TLS LFB System BIW06, FNAL, May 1~4, 2006

17 ParameterValue Energy, E1.5 GeV RF frequency, f RF 499.654 MHz Harmonic number, h200 Revolution frequency, f rev 2.49827 MHz Momentum compaction factor 0.00067 Operating current, I B 300 mA (March 2006) Synchrotron frequency, f s 33.7 kHz Synchrotron tune, s 0.0136 Down-sampling factor, D4 Bunch sampling frequencyf rev /4 = 625 kHz Working frequency of the phase detector 3 f RF (or 6 f RF ) Phase detector range ± 30 o (± 15 o ) Taps of feedback FIR filterup to 50 Parameters of the Longitudinal Feedback System Response of the Prototype FIR Filter BIW06, FNAL, May 1~4, 2006

18 s ~ 0.0136 C = 120 m T rev = 400.2 ns f rev = 2.49827 MHz f s = frev/4 = 625 kHz R5 R4 R3 R2 R1 R6 R5BPM4 (A+B+C+D) Longitudinal Kicker Layout of pickup & kicker Beam Position Monitor (Energy Oscillation Detector) Longitudinal Kicker (Energy Correct Kick) Power Amplifier Feedback Electronics BIW06, FNAL, May 1~4, 2006

19 Block Diagram of the Longitudinal Bunch-by-Bunch Feedback System AB CD ADC 50tapFIR ADC 50tapFIR DAC FPGA Clock 124.913 MHz 499.654 MHz 200 W 53 dB 30 dB LVDS I-Techs RF Front-End 499.654 MHz SSB Or QPSK Modulator Milmega AS0814-250R 0.8 GHz ~ 1.4 GHz 20 dB 1500 MHz (SSB) or 1375 MHz (QPSK) Buffer and Delay Module 8 ns 4 ns 2 ns 6 ns Longitudinal Kicker X 4 X 3 BBF Clock Generator Clock/4 = 124.913 MHz Clock/4 = 124.913 MHz # 1, 5, 9,.. 197 # 3, 7, 11,.. 199 # 2, 6, 10,.. 198 # 4, 8, 12,.. 200 BIW06, FNAL, May 1~4, 2006

20 SSB Modulator RF Output Monitor I Q Excitation On/Off Control Correction Signal 499.654 MHz Frequency Multiplier 90 o 0o0o Phase Shifter QPSK Modulator AD8131 Differential Amplifier MiniCircuits Amplifier Sirenza STQ-2016 700-2500 MHz Direct Quadrature Modulator USB or LSB Selection PULSAR QE-14-442 90 o Hybrids (2~250 MHz) Shut-down control Beam Spectrum BIW06, FNAL, May 1~4, 2006

21 Loop Open 40 msec Temporal Behavior of Longitudinal Instability Build-up Loop Open 100 msec Longitudinal Instability Signal BIW06, FNAL, May 1~4, 2006

22 Beam Phase and Beam Spectrum with Feedback Loop Open and Closed Beam Spectrum (Open-Loop vs. Closed-Loop) 62.5 MHz peak is due to filling pattern with 16 nsec periodicity 2 nd harmonic of 62.5 MHz Filling Pattern Beam Phase w/o LFB Beam Phase w LFB Beam Spectrum Details w/o and w LFB BIW06, FNAL, May 1~4, 2006

23 Longitudinal Grow/Damp Experiments @ 250 mA BIW06, FNAL, May 1~4, 2006

24 Streak Camera Observation Loop Open Loop Closed One Turn Loop Closed -> Open -> Closed One Turn Loop Open Snapshot of the Synchrotron Radiation Beam Profile Loop Closed Loop Open BIW06, FNAL, May 1~4, 2006

25 Current Status of the Longitudinal Feedback System Stable operation have been achieved in users shift. Increase the beam brilliance at the results. Various feedback filters will be try to improve system performance. Improve aspect form operation point of views are same as transverse feedback system. BIW06, FNAL, May 1~4, 2006

26 V. Summary Two major upgraded have been completed recently for the TLS. - SRF cavity - Top-up operation Transverse feedback system upgrade from analog to digital system in late 2005. Longitudinal feedback system commissioning successful in early 2006. Both the transverse and longitudinal feedback loop adopt the SPring-8 same feedback processor - SPring-8 designed feedback processor. SLS Modified SLS longitudinal kicker is used. SLAC SLAC analysis code is adopted for transient signal analysis. Both systems put into service immediately after commissioning. Improved the system performance and functionality is on going. BIW06, FNAL, May 1~4, 2006

27 Acknowledgements Many peoples contributed to this project directly or indirectly. Thanks for their help. T. Nakamura, K. Kobayashi (JASRI/SPring-8) M. Dehler (SLS/PSI) M. Tobiyama (KEKB) J. Fox, D. Teytelman, S. Prabhakar (SLAC) J. Seebek (SSRL), G. Strover, J. Byrd (LBNL) Thank You for Your Attention ! BIW06, FNAL, May 1~4, 2006


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