1. New PS one-turn delay feedbacks and further developments Thanks to Alfred Blas, Heiko Damerau, Guido Sterbini, Simone Gilardoni, Letizia Ventura, Valentin Desquiens and all involved people from sections BE-RF-FB, IS and CS Damien Perrelet BE-RF-FB CERN LIU-DAY 2014, 11 April 2014

2. Content Overview of the new feedback board Current implementations : -PS 10 MHz 1-turn feedback and AVC digital loops -PS transverse damper Developments and ideas: -PS 1-turn feedback cavities 13/20/40/80 MHz -PS longitudinal coupled-bunch feedback -PSB/AD/LEIR transverse damper Summary and outlook 3/21/2014Damien Perrelet BE-RF-FB CERN2

3. The new hardware 3/21/2014Damien Perrelet BE-RF-FB CERN3

4. RF from BC Gap Return DRIVE IN Power Combiner 1TFB TP AVC TP New PS feedback hardware Power Combiner CLK DWSTR1 FPGA Stratix II EPS2S90F1020C4 Clock Distri NODLY  UPSTR  nUPSTR  DWSTR1  DWSTR2 4 SERIAL LINKSVME + TRIGGERS ADC2 ADC1 ADC4 ADC3 LP DAC1 DAC2 DAC3 DAC4 LP ADCs AD6645 DACs AD9754 G Ctrl LMH6702AD8009 G Ctrl 3/21/2014Damien Perrelet BE-RF-FB CERN4 Vprog Test VGAP DET TP VPROG TP Spare CLK DWSTR2 h 200 BP1 SRAM 50 MHz CLK UPSTR 4 ADC RF INPUT CHANNELS → FPGA → 4 DAC RF OUTPUT CHANNELS Digital

5. Electronic board 3/21/2014Damien Perrelet BE-RF-FB CERN5 -Generic VME board -STRATIX II FPGA and external SRAM -4 RF channels ADC and DAC, low latency, 14 bits and running at 105/125 MSPS -2 multiplexed fine delay lines for glitch-free delay changes (DAC and FPGA clocking) -4 serial links CVORB or fast 40 Mbit/s

6. PS 10 MHz 1-turn delay feedback 3/21/2014Damien Perrelet BE-RF-FB CERN6

7. PS 10 MHz cavity feedback overview 3/21/2014Damien Perrelet BE-RF-FB CERN7 AVC 1TFB hnhn h 200 Final amplifier, 2.8-10 MHz cavity, fast wideband FB DACADC DAC Gap return Drive H - Slow voltage control loop (AVC)  Gain control at f RF Reduction of cavity impedance seen by the beam: - Fast wide-band feedback around amplifier (internal)  Gain limited by delay - 1-turn delay feedback  High gain at n  f rev V prog ADC RF from BC

8. 1-turn delay feedback hnhn NOTCH FILTER COMB FILTER AUTO DELAY DAC ADC VGAP Detected 1TFB OUT to Drive FPGA VME INTERFACE  UPSTR  DWSTR RF CLK h 200 NOTCH BYPASSVPROG 8/4/2014Damien Perrelet BE-RF-FB CERN8 Suppress the RF component to not work against AVC High gain at f rev multiples Resulting transfer function hnhn IIR fractional notch h n /h s Periodic comb at f rev Unique sampling clock h 200 integer multiple of the revolution frequency DPRAM Fine delayed clock

9. Measurements with beam on ToF and AD cycle before LS1 frequency FB off 10 db/div FB on 10 db/div 3/21/2014Damien Perrelet BE-RF-FB CERN9 Open and closed loop transfer functions Spectrum at cavity gap voltage of a single high intensity bunch 8∙10 12 ppb Beam induced spectrum of four bunches during batch compression h = 8  13  20 frequency amplitude h = 8

10. PS 10 MHz digital AVC loop 3/21/2014Damien Perrelet BE-RF-FB CERN10

11. hnhn AVC loop and AVC surveillance 3/21/2014Damien Perrelet BE-RF-FB CERN11 Gap return Power amplifiers - Error[k] + PID controller DAC ADC Cavity 10MHz ADC non-IQ demodulation CORDIC I Q Detected gap voltage Modulator AVC drive RF from beam control Voltage program H. Damerau, V. Desquiens, M. Haase, D. Perrelet Veto RF-FBRF-IS RF veto Collaboration  Voltage detection using non-IQ algorithm at given harmonic h n  High power hardware safety ensured by separate surveillance module

12. Digital AVC loop measurement 3/21/2014Damien Perrelet BE-RF-FB CERN12  Digital PID with adjustable parameters  Regulation to full voltage without overshoot in about 15 turns Vprog Vdet Error RF drive 100  s/div10  s/div Vprog Vdet Error RF drive Step response of the controller around a cable 500  s test voltage program Response with fast voltage rise

13. Installation in the machine 3/21/2014Damien Perrelet BE-RF-FB CERN13 Four new VME crates installed in building 359 (one for each tuning group) Example for tuning group B (cavities C56, C66, C76 and C81)

14. PS transverse damper 3/21/2014Damien Perrelet BE-RF-FB CERN14 A.Blas, S.Gilardoni, G.Sterbini

15. 3/21/2014Damien Perrelet BE-RF-FB CERN15 PS transverse feedback Firmware → A. Blas 1)PU flight time compensation → 4 pipeline delay with h 200 2)Orbit offset suppression → Periodic notch filter on h 200 3)Phase compensation at betatron frequencies → Hilbert filter h 200 4)Automatic delay to complete 1 turn → DPRAM + fine delay lines

16. 3/21/2014Damien Perrelet BE-RF-FB CERN16 PS transverse feedback 10 ns/div PS TFB ON 10 ns/div PS TFB OFF → Present PS TFB designed to damp 44 μm/turn at 1.4 GeV (BW 23 MHz). A.Blas, S.Gilardoni, G.Sterbini Damping of injection errors Damping of head-tail instability Transverse damper to cure horizontal and vertical transverse instabilities

17. 3/21/2014Damien Perrelet BE-RF-FB CERN17 PS transverse feedback 26 GeV / 72 bunches of 11e10 / LHC 25 ns TFB OFF Delta V Delta H Sigma TFB ON Histogram of losses sum from C170 to C300 1.4 GeV / 600e10 single bunch / ToF cycle A. Blas S. Gilardoni G. Sterbini

18. New applications 3/21/2014Damien Perrelet BE-RF-FB CERN18

19. PS 1-turn feedbacks cavities 13/20/40/80 MHz 3/21/2014Damien Perrelet BE-RF-FB CERN19 1) → Analog down-conversion to IF → Analog to digital conversion → Digital processing in IQ with existing board → Digital to analog conversion → Analog up-conversion or 2) → Direct sampling and/or undersampling with existing board or 3) → Modification of existing board to achieve higher sampling capabilities or 4) → Build a complete similar new and fast board Thomas Truszczyński Frequency conversion board Mini-PCB to fast ADC adaptation

20. 3/21/2014Damien Perrelet BE-RF-FB CERN20 PS longitudinal coupled-bunch feedback Detect at h = 13  damp with C10-11 at h = 8 H. Damerau, L. Ventura Cross-damping : h det + h kick = h RF = 21  Need to flip side-bands up/down See talk Letizia Ventura! ADCDAC Beam (WCM) Longitudinal kicker (Finemet)

21. Developments and future applications 3/21/2014Damien Perrelet BE-RF-FB CERN21 Developments: -PS 1-turn feedbacks for high frequency cavities -PS longitudinal coupled-bunch feedback -PSB, AD and LEIR transverse dampers PS 10 MHz possible improvements: -Cavity phase loop (Reliability of RF manipulations) -Cavity phase compensation (More gain for 1-turn feedback) -Multi-harmonic RF generation on-board and use of h s =256

22. Summary and outlook - New generic feedback board meets requirements → Complex design but easy to use and allows lots of features -Two operational loops: PS 10 MHz 1-turn feedback and AVC → Fully digital and remote controlled → Commissioning during setting-up 2014 - New operational PS transverse damper → Good results and required for LIU beams - Many future developments and projects using this hardware → FPGA gives reliability and flexibility for new ideas 3/21/2014Damien Perrelet BE-RF-FB CERN22

23. Thanks for your attention 3/21/201423Damien Perrelet BE-RF-FB CERN Many thanks to people from sections RF/FB-CS and RF/FB/IS for collaboration and support : Heiko Damerau, Wolfgang Hofle, Alfred Blas, Philippe Baudrenghien, Maarten Schokker, Jose Noirjean, Gregoire Hagmann, Tom Levens, Michael Jaussi, John Molendijk, Valentin Desquiens, Matthias Haase, Guido Sterbini, Simone Gilardoni, Letizia Ventura.