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LLRF & Synchronization System + Roadmap

LLRF & Synchronization System + Roadmap. On behalf of the LLRF and Laser based Synchronization team. Presented by H. Schlarb. Outline. LLRF upgrades and developments at FLASH - Decision to keep MO frequency at 9MHz => Software & Hardware will be identical to XFEL

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LLRF & Synchronization System + Roadmap

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  1. LLRF & Synchronization System+ Roadmap On behalf of the LLRF and Laser based Synchronization team Presented by H. Schlarb

  2. Outline • LLRF upgrades and developments at FLASH - Decision to keep MO frequency at 9MHz => Software & Hardware will be identical to XFEL => Implementation of uTCA based system at FLASH 2011/2012 => XFEL software development has basically started! • Highlights from FLASH operation • Overview on synchronization + some recent results • Roadmap (Tuesday …) 2

  3. Overview on LLRF systems at FLASH Laser ~ ~ BC3 ACC4 ACC4 ACC4 ACC7 Gun ACC1 ACC2 ACC3 BC2 3rd A A A A A A LLRF LLRF LLRF LLRF LLRF LLRF 3

  4. Upgrade of LLRF system • Upgrade of all RF stations using SimconDSP controller • Gun/ACC23/ACC45/ACC67 • IF=250kHz, IQ-sampling scheme • Sampling rate 81MHz (use averaging) • RF control for 3.9GHz • Probe, forward and reflected signals • New RF down converter & LO generation with IF=54MHz, non IQ-sampling, LO = 3954MHz • Sampling rate 81MHz 10 Channel 14bit ADCs 81 MHz clock rate 8 DAC, 14 bits 2 Gigalinks FPGA: XILINX Virtex II pro 4

  5. Upgrade of LLRF system • Upgrade of all RF stations using SimconDSP controller • RF control for 3.9GHz • New cabling in injector racks • MO1 & MO2 cabling completed • New rack & cabling for RF gun • New rack & cabling for ACC1/ACC39 • Enclosed racks for better temperature stability • Parallel cabling for development system • Careful noise investigation and power level adjustment of LO and RF signals RF gun ACC39 ACC1 MO ACC39 DWC 5

  6. Upgrade of LLRF system • Upgrade of all RF stations using SimconDSP controller • RF control for 3.9GHz • New cabling in injector racks • Upgrade & unified FPGA controller firmware • Multiple feed forward table (main/beam loading/correction) • Multiple setpoint table (main/beam based correction) • Model based Multiple In Multiple Out (MIMO) controller • Charge correction & intra-train beam based feedback • Exception & Error handling, limiters • Error and status displays Scheme of LLRF RF controller Feed forward table architecture 6

  7. Upgrade of LLRF system • Upgrade of all RF stations using SimconDSP controller • RF control for 3.9GHz • New cabling in injector racks • Upgrade & unified controller firmware • Unified and new control software • New C++ architecture for front end server • LLRF library based on SysML approach • Unified naming convention • Automatic firmware downloads • Finite State Machine for automation • High level software: diagnostics, calibration… • DAQ integration • Model based learning feed forward (LFF) • Loop phase/gain correction • Piezo control for cavity detuning comp. • … Voltage [MV] Phase [deg] LFF off LFF on 1st bunch 7

  8. Upgrade of LLRF system • Upgrade of all RF stations using SimconDSP controller • RF control for 3.9GHz • New cabling in injector racks • Upgrade & unified controller firmware • Unified and new control software • Beam signals integrated • Charge signals • Bunch Arrival time • Pyro signal • Real time FB with matrix • Limiter on Ampl/Phase corr. • IIRF filters • Rep. rate adaption • Charge scaling of beam load compensation table Control software ~ 90 % completed Most of features are commissioned 8

  9. Upgrade of LLRF system • Upgrade of all RF stations using SimconDSP controller • RF control for 3.9GHz • New cabling in injector racks • Upgrade & unified controller firmware • Unified and new control software • Beam signals integrated • Piezo drivers • new driver for ACC1 / ACC7 • DAQ server for detuning measurements • Several piezo studies performed • Active compensation of ringing • DC voltage added for static detuning Control software ~ 80 % completed But many features not fully commissioned 9

  10. Upgrade of LLRF system 10

  11. Process control via FSM Slow BBF correction SP filling correction Resonance filling Static detuning correction Dyn. detuning correction SP_CORR table ≤ VM offset corr. DCW calibration BLC adaptation a b c d LLRF Control Tables – software philosophy - Operator & FSM & LLRF expert Setpoints: A, & Parameters: timing, … - As larger impact on cavity/coupler the more restriction on table/table generation - Separation of physics cause of effect - Easier exception handling ratio Beam based SP correction Model based FF & SP tables Bunch Pattern Learning Feed forward ≤ SP table SP_BBF table SP_USER table FF_BLC table FF_CORR table FF table ≤ ≤ ≤ Slow FB loops for parameter optimization Q MPS + + Q - Beam signals Rot FF-total table Loop G/ ≤ MPS - + DAC Controller ≤ Field detection Rot DAC 11

  12. On-crest acceleration phase • Definition and adjustment (min. energy spread/ max acceleration) • Drifts of down converter + cables (~1-2deg) -> hardware changes 2011 • Difference between Setpoint and Vectorsum -> software done • To some extend drifts from laser arrival time + conv. -> hardware changes 2011 • On-crest phases a dominated by operation set-point (support panel) Remark: 1% ACC1 gradient change 3.5 phase difference for all downstream modules 12

  13. FLASH results: Learning Feed Forward 13

  14. FLASH results: Learning Feed Forward 4 ps 0.5 ps 14

  15. FLASH results: with MIMO (ACC39) Value Repetitive error (aver. 100 macro-pulses) Pulse to pulse (each time stamp) PKPK Rms Abs. • Limited by ADC bit noise • LFF off 15

  16. FLASH results: Performance LLRF • Arrival time measurements Typically values 60-100fs rms from injector 60-80fs rms behind BC2 50-60fs rms exit LINAC Pulse to pulse about factor of 2 better than last year Across bunch train dA/A~7e-4 (LFF was off 250kHz@0.5nC) RMS timing jitter 400fs 16

  17. FLASH results: Gradient stability ACC1/ACC39 shutdown shutdown 17

  18. Gradient Tilts vs Beam Current (ACC7) +5 +3 ~2.5% 0 Gradient change over 400us (%) -3 -5 Intended working point 3 4 5 1 2 Beam Current (mA) FLASH results: Performance at 4.5mA operation • Characterisation of solution by scanning beam current • model benchmarking Flat gradient solution achieved • 4.5 mA beam

  19. Energy stability over 3hrs with 4.5mA ~0.02% pk-pk 9 Feb 2011 FLASH results: Performance at 4.5mA operation 15 consecutive studies shifts (120hrs), and with no downtime Time to restore 400us bunch-trains after beam-off studies: ~10mins Energy stability with beam loading over periods of hours: ~0.02% Individual cavity “tilts” equally stable • Concept with toroid based BLC scaling worked excellent (at least up to 4.5mA) 19

  20. FLASH results: Beam base FB (with MIMO & LFF) Laser ~ ~ BC3 BC2 Gun ACC1 ACC2 ACC3 ACC4 ACC7 3rd Latency of system Exit of linac & out-of-loop • Both intra-train FB on • MIMO controller • Repetitive pkpk deviation < 100fs < 22 fs 20

  21. Open software developments: Next steps (till end of FLASH run) • Firmware & Software for RF gun (consistent to SRF) • Automation and permanent usage of DC/AC piezo operation • MIMO controller including BBF • Setpoint correction during filling / resonance filling using phase slopes • Forward peak power reduction • Improved error handling • Rapid VS calibration • Improved DAQ implementation and long term statistics • Error budget management & optimization of loops for LLRF parameters • LO table correction

  22. Layout of uTCA LLRF system 1. Project phase (19“ modules, uTCA without backplane) Complicated cable management - LLRF RTM backplane concept 22

  23. Layout of uTCA LLRF system 2. Project phase (19“ modules, uTCA with backplane) Higher risk of signal degradation … (for main linac eventually only) TT Interne Diskussion Frank Ludwig, Tomasz Jezynski, DESY 23

  24. Activities and milestones scheduled for Jan. 11 -> Jun. 11 Main components of uTCA based LLRF system: Typically 2-3 revision required for each, 3-6 month per revision Components With whom Status Expected uTCA crate (EMI/PS noise/…)* indu./indu. rev1/prod. Jun/Jan11 ADC board (16bit/10Ch)* with industry revision 1 Mar. 2011 Low noise DCW* in-house/indu. start rev 1. May 2011 Vector modulator* collaboration routing Mar. 2011 AMC controller collaboration production Feb. 2011 LO generation (19’’)* collabr./in-house design May 2011 LO distribution (19’’) collabr./in-house design Mar. 2011 LO generation (RTM)* industry contacted Aug. 2011 Calibration unit (19’’)* collabr./in-house design Apr. 2011 uTCA back plane* collabr./indu. production May 2011 Piezo driver board collabr. design June 2011 * Indicates ultra high performance (<150dBc/Hz , clk ~200fs , <10fs stab., -80dB cx-talk) usually not available in industry (close collaboration / exchange important / few companies)

  25. Software developments uTCA 2011 Most important is the transition from SimconDSP -> uTCA!!! • Firmware & Communication protocols & Front-end server • Middle layer server can be move to front-end CPU • Implementation of new Timing/Clock 2012 New software developments feasible • Down-converter calibrations (directly into performance) • Make us of Pfor/Pref within controller (e.g. real time quench det./model) • 30Hz operation with 9MHz tables & 96 channels (DSP???) • AMTF software developments for routine measurements • Upgrade of beam base feedbacks … 2013/2014 • Control software for 25 RF stations XFEL • Energy management …

  26. uTCA based LLRF Systems & schedule 2011 • REGAE (May-July) 1 Crate (8) • FLASH ACC1/ACC39 (June-Sep) 1 Crate (24/12) Shutdown 12.09. • PITZ TDS (Aug-Sep) 1 Crate (8) • CMTB (Sep) 1 Crate (24) • FLASH ACC23/ACC45 (Sep-Dec) 2 Crates (48/48) DWC/ADC? 2012 • Freeze final LLRF design • FLASH ACC67 1 Crate (48) • FLASH ACC45 1 Crate (48) Semi-distr. • AMTF (March) 3 Crates (24/24/24) • Final revision (Oct.) • Start mass production 2013 • XFEL L0 2 Crates (36/36) 2014 • XFEL L1-L3 50 Crates (96)

  27. t f = t f 2) Carrier is optically f ~ GHz MZT ~ 3) Carrier is optically + detection f ~ 200 THz ~ 4) Pulsed source f ~ 5 THz Mode locked Laser OXC Synchronization system approaches 1) RF distribution f ~ 100MHz …GHz ~ 27

  28. Hybrid system for FEL facilities Reliability RF System CW optical Pulsed system Performance Costs 28

  29. Layout of XFEL Synchronization System 29

  30. EDFL, soliton, t~200fs,f=216MHz SESAM, P > 100mW, phase noise < 5fs (1kHz) Free space distribution + EDFA Dispersion comp., Polarization contr., Collinear bal. opt. cross-corr. Desired point-to-point stability ~ 10 fs Optical synchronization system Laser MLO MO-RF Narrow Band. Distribution Optical link Optical link Optical link <5fs <5fs <5fs Other lasers Direct End-station LO-RF EOMs/ Seeding Direct/ Interferometer Two color bal. Opt. cross-corr. Arrival beam/laser DWC/Kly Laser pulse FB A &  cavity Main issue: robustness, stability and maintainability Prototype at FLASH 09.12.2010, Daresbury, “Rule of lasers in particle beam research” Holger Schlarb, MSK, DESY 30

  31. Optical Synchronization SystemInstallation at FLASH • Master Laser Oscillator (RF locked to MO) • Free space distribution system to 16 ports • Optical Links: 6 stabilized using OXC & 1 passive • Front-ends • 4 Bunch arrival time monitors (BAM) • OXC for INJ / TiSA lasers • RF locked for TiSA (HHG) (not yet completed) 31

  32. Bunch Arrival MonitorDetector 32

  33. Bunch Arrival MonitorsFront-end Electronics Top view to LLRF Bottom view 33

  34. Fiber Link Stabilization (RF based) Frequency domain Time domain Every odd harmonic destructively interfere Amplitude detection with mixer (sign) of high harmonics (45th) allow to measure link delay variations Scheme RF link 34

  35. Fiber link stabilization (RF based) Optics section Digital FB loop LO generation In-loop Detector branch Out-of-loop Detector branch 35

  36. Fiber link stabilization (RF based) Error between in-loop and out of loop ~ 0.8fs rms, 4.8 fs pkpk, (30 m long fiber in laboratory, not stabilized, only monitored) In-loop / 2 Out-of-loop 38 hours difference overcomes AM-PM conversion in photo-detectors several advantages compared to OXC link (low opt. power, monitoring possible, simple disp. comp.) low cost version link with still high performance 36

  37. RF generation from optical pulses Frequency domain Time domain Phase noise 100fs Photo Detector Bandwidth PD frep T = 5ns = 1/frep Direct conversion with photo detector (PD) • Low phase noise (to be proven at end-station) • Temperature drifts (0.4ps/C°) • AM to PM conversion (0.5-4ps/W) • Potential for improvement (corporation with PSI) f = n*frep laser pulses PD BPF ~ ~ ~  frep f = n*frep Sagnac loop interferometer • balanced optical mixer to lock RF osc. • insensitive against laser fluctuation • Very low temperature drifts Results: f=1.3GHz jitter & drift < 10 fs rms limited by detection Remark: much easier at hire frequencies … MZI based balanced RF lock • new scheme, under investigation 37

  38. Results double balanced MZI-L2RF Sensitive to environment 2fs pkpk But insensitive to laser power But 0.8 ps/K temperature dependence 38

  39. Thanks for your attention 39

  40. Beam Based FeedbackInstallation Laser ~ ~ BC3 BC2 Gun ACC1 ACC2 ACC3 ACC4 ACC7 3rd Toroid Toroid Toroid A A A A BAM BAM BCM BAM BAM BCM LLRF LLRF LLRF LLRF LLRF Beam Based Feedbacks: • BAM before BC2 corrects phase in RF-Gun • BAM and BCM after BC2 simultaneously correct amplitude and phase in ACC1 and 3rd harmonic • BAM and BCM after BC3 correct amplitude and phase in ACC23 Results from BBF running at BC2 40

  41. Master Laser Oscillator (MLO)Pulse generation and distribution • Promising: OneFive ORIGAMI-15 • Repetition rate: 216,66MHz • Average power: > 100mW • Pulse duration: p < 150 fs • Integrated timing jitter < 5 fs in the interval [1 kHz; 10MHz] • Mechanically robust, easy to maintain 41

  42. Balanced optical cross-correlator - Det 2 Det 1 Fiber Link Stabilization (optically) 216 MHz Er-doped fiber laser J. Kim et al., Opt. Lett. 32, 1044-1046 (2007)

  43. Fiber Link Stabilization (optically) 3 generation of opto-mechanics typical in loop jitter ~ 1-2 fs rms (also smaller) Experience: Operate reliably Ampl. FB to be add Smaller open questions XFEL: Dispersion management need to be improved Delay stage too short for long links and large temp. changes Courtesy: M. Bock 43

  44. Low Level RF Control SystemsIntra-train BBF Implementation Control System Toroid LLRF Control Tables Qtoroid Charge Measurement LLRF SP Table ADC9 Pyro SP Table I Q BCM ΔU ΔΦ Peak Detection Gating Charge Correction - SP Signal Modulation ADC10 Transfer Matrix BAM tsample Qnom ΔA/A Δt Optical Link I Q FPGA MPS 44

  45. ? measure scanning BBF CalibrationTransfer Matrix Determination BC2 ACC1 Gun ACC39 Pyro BAM A/ A/ t C/z Actuators Monitor system ACC1 ACC39 extract 45

  46. Open issues: observation QL changes • Voltage change ACC45 from 67MV to 255MV (~4MV/m -> ~15MV/m) ACC5 ACC4 Decay over time No change at all 17MV/m 2.6 -> 3.0 (16%) 2MV/m 10 min 10 min • Cause need to be investigated (likely main coupler antenna position change due to thermal expansion) 46

  47. Open issues: Cavity pre-detuning using DC piezo voltage Successfully used to change pre-detuning 10V 0V 0V 10V • Is accompanied with Ql changes => detuning via Lorenz force detuning • For some cavities orbit changes are observed reduces SASE, but simple corrector sufficient  global orbit FB essential for reproducibility of machine operation • Several studies on detuning compensation during macro-pulse • Since 4 weeks PZT for ACC67 in operation (DC/AC) 47

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