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ILC Timing

ILC Timing. Frank Lenkszus Controls Group Advanced Photon Source Argonne National Lab. Timing Functions. Master oscillator distribution (1.3 GHz) 5 Hz timing fiducial distribution Programmable triggers for field hardware Mechanism to synchronize software processing to timing events

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ILC Timing

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  1. ILC Timing Frank Lenkszus Controls Group Advanced Photon Source Argonne National Lab Frank Lenkszus Advanced Photon Source

  2. Timing Functions • Master oscillator distribution (1.3 GHz) • 5 Hz timing fiducial distribution • Programmable triggers for field hardware • Mechanism to synchronize software processing to timing events • Time fiducials for synchronized timestamps for software and hardware events. • Develop pulse ID number to identify pulses within the 1 millisecond pulse train • ID number will accompany data relating to individual pulses Frank Lenkszus Advanced Photon Source

  3. Key Parameters that Influence Timing Frank Lenkszus Advanced Photon Source

  4. Timing Global Specifications • Timing Phase locked to RF System • Stability at the point of RF measurement and control: ~10 picoseconds • Short Term Stability for Bunch Compressor: ~100 femtoseconds • Timing phase reference will be distributed via active phase stabilized redundant fibers in star configuration to sectors • Fiber cable has temperature coefficient: ~10 ppm/ oC • Timing phase reference to be dual redundant with auto failover • Timing phase reference distribution will use active phase stabilization • Phase shifter will be based on fiber in a temperature controlled oven • Will build on prior work for NLC and TELSA • Local distribution (~500 meters) will be via coax • Active phase stabilization scheme • Phase averaging scheme • 5 Hz timing fiducial will be encoded on timing phase reference by momentary phase shift • Others have used Amplitude Modulation. Frank Lenkszus Advanced Photon Source

  5. Timing Global Specifications (Cont.) • Required timing triggers and other frequencies will be developed locally at sector locations from the distributed phase reference • Local timing triggers will be developed by counting down phase reference • Graded approach to timing trigger generation • High precision: (pico-second) • Medium precision (nano-second) • Low precision (microsecond) (Event System) Frank Lenkszus Advanced Photon Source

  6. Prior Work On Phase Reference Distribution • TELSA • “First Generation of Optical Fiber Phase Reference Distribution System for TESLA”, Krzysztof, C., et al, TELSA Report 2005-08 • NLC • A High Stability , Low Noise RF Distribution System”, Frisch, J., et al, Proceedings of 2001 PAC, Chicago, pp 816 – 818 • “R&D for the ILC Phase/Timing Distribution System”, Frisch, J. 10/20/04 • KEK • KEK (“RF Reference Distribtution Using Fibre-Optic Links for KEKB Accelerator”, Natio, T. et al, PAC2001) Frank Lenkszus Advanced Photon Source

  7. TELSA Reference Distribution Specifications • Short Term Stability (phase noise) << 1 ps, (10 fs at XFEL) • Short term stability (minutes) < 1 ps at RF frequency (0.5o @ 1.3 GHz) • Long term stability (days) < 10 ps (5.0o @ 1.3 GHz) • System Length: up to 15 km • Distributed frequencies 9-2856MHz (Tests done at1.3GHz) • High Reliability Frank Lenkszus Advanced Photon Source

  8. TESLA Features • Use 1550 nm DFB Laser • Temperature controlled to 25 oC • Use SMF-28 fiber (Corning) • Loss < 0.22dB/km @ l = 1550 nm => 4.4 dB for 20 km fiber • Phase Shifter • 5km fiber inside an oven with 30 oC temperature range • Compensates for phase changes induced by 10 oC temperature change of 15 km link • Digital PID controller • Only PI gains used • Transmit 1.3 GHz reference Frank Lenkszus Advanced Photon Source

  9. TESLA Frank Lenkszus Advanced Photon Source

  10. TELSA System Performance • Integrated system test had problems • Had to reduce PID P gain to make system stable • Caused by phase shifter dead-time • Couldn’t run tests for more than 5 -15 hours because of software malfunction • Stability • Short Term Stability 0.3 psec • Long Term Stability 2 psec Frank Lenkszus Advanced Photon Source

  11. NLC Requirements • Transmission length : 15 km • Noise 10 sec to 10 kHz: < 0.12 psec RMS • Stability < 1 hour: +/- 1 psec • Stability Long Term: +/- 5 psec • Temperature Stability: < 2x10-8/oC Frank Lenkszus Advanced Photon Source

  12. NLC Prototype Features • Use 1550 nm DFB Laser • Laser pulsed at 3125 Hz to avoid interference between forward and reflected power. • Use SMF-28 Single-mode fiber 15 km long • Phase Shifter • 6km fiber inside an oven • Oven continuously cooled by TEC cooler and heated by a wire grid. • Prototype operated at 375 MHz carrier • RF signals mixed down to 25 kHz IF and digitized at 200 kHz. • Phase measured digitally in PC. • PID loop implemented in PC to drive phase shifter • All RF components and optical components were mounted in a temperature controlled oven. • Test output signal filtered with 100 Hz bandwidth VCXO phase locked loop to reduce broadband noise. Frank Lenkszus Advanced Photon Source

  13. NLC Test Setup Frank Lenkszus Advanced Photon Source

  14. NLC Prototype Performance • System Phase stability: 10 femtosecond per degree C per kilometer • Phase Noise 0.1Hz to 10 kHz: 0.25 psec RMS • Later report of ~0.1 psec • Stability < 1 hour: +/- 0.75 psec • Stability Long Term (1 month) : +/- 2 psec • Later report of +/- 1 psec • Temperature Stability: < 10-8/oC Frank Lenkszus Advanced Photon Source

  15. Variations • KEK (“RF Reference Distribtution Using Fibre-Optic Links for KEKB Accelerator”, Natio, T. et al, PAC2001) • Used Phase Stabilized Optical Fiber (PSOF) : 0.4ppm/oC (-10 to 30 oC) • Used WDM (1310 (Forward) and 1550 (Reflected) nm to avoid crosstalk • Avoids RF chopping • Distributes 509MHz • Temperature stabilized phase shifter • Electronically controlled varactor diodes • Phase stability: ~ 2 degrees for 4.8 km PSOF cable Frank Lenkszus Advanced Photon Source

  16. Active Phase Stabilized Link Frank Lenkszus Advanced Photon Source

  17. Redundant Reference Transmission with Failover Frank Lenkszus Advanced Photon Source

  18. Sector Timing Distribution Frank Lenkszus Advanced Photon Source

  19. Sector Timing Controller Frank Lenkszus Advanced Photon Source

  20. Other Frequencies • Other generated frequencies will be sync’d to 5 Hz timing fiducial • 3.25 MHz Injector (1/400 1.3GHz) • Reference: BCD2005 General Parameters: 308 ns Linac Bunch Interval. • 6.5 MHz Injector (Low Q option) (1/200 1.3 GHz) • Reference: BCD2005 General Parameters: 154 ns Linac Bunch Interval • 500 MHz DR (5/13 1.3 GHz) • 46.3 kHz Electron (6 km) DR Revolution Clock (500MHz/Harmonic #) • 23.15 kHz Positron (12 km) DR Revolution Clock (500MHz/Harmonic #) • 54 MHz Mode Locked Lasers (1/24 1.3 GHz) Frank Lenkszus Advanced Photon Source

  21. Event System • Bit serial system sends event codes • Synchronous to 5 Hz and sub harmonic of 1.3 GHz • Possible events • Start of Bunch Train • 5 Hz • MPS Trip • Pulse Tic • Revolution Clock(s) (DRs) • GPS Clock Tick • Event Receivers • Generate interrupt to processors to synchronize software processing • Time stamp counter • Low grade timing triggers on occurrence of specified events Frank Lenkszus Advanced Photon Source

  22. Numerology • Items that influence flexibility in bunch pattern choice • Ratio of ML to DR RF (1300/500 => 13/5) • DR Harmonic number • Linac bunch spacing (nominal 308 nsec => 3.24 MHz) • References that explore the relationships. • “Basic Timing Requirements for TELSA”, Kriens, W. TELSA Report • “Some Timing Aspects for ILC”, Ehrlichmann, H, DESY, Presented at GDE Freascati, December 2005. Frank Lenkszus Advanced Photon Source

  23. Some Timing Issues • Fiber oven phase shifters are large and consume significant power (~ 1kW/fiber) • Chop RF frequency or not – Avoid Circulator cross-talk • NLC chopped at 3125 Hz • TELSA – cross talk constant so don’t worry about it • KEK used WDM (1300/1500 nm) • Bunch Compressor • Required stability at the cavities not demonstrated when transmitted over long distances • Local reference distribution • Active Phase Stabilization • Can we assume temperature stable enough through ½ sector so phase stabilizer not required for each local node. • Phase Averaging • Requires directional couplers at each drop point . Frank Lenkszus Advanced Photon Source

  24. Local (IntraSector Reference Distribution) Reference: Frish, J. “R+D for the ILC Phase/Timing Distribution System”, 10/20/04 Frank Lenkszus Advanced Photon Source

  25. Timing Questions • Under what conditions should timing cause an MPS trip • Unrecoverable phase distribution error • Interfaces/Timing Requirements: • MPS • BDS • Timing Requirements for Accelerator Components • Table • Number, Range, Resolution, Accuracy, Stability, Jitter • Kickers • Bpms • Laser Wire • Etc • Bunch Compressor • Most stringent timing requirement • Master Oscillator Specification Frank Lenkszus Advanced Photon Source

  26. Work to be done on Phase Distribution • Establish stability/phase noise budget • Master Oscillator • Long haul distribution • Bunch Compressor • All other • Local (Intra Sector distribution) • Prototype phase stabilized link building on NLC/TELSA work • Extend prototype to redundant configuration • Develop and test auto failover • Investigate options to distribute phase reference to Bunch Compressors Frank Lenkszus Advanced Photon Source

  27. Timing Requirements • Gather list of devices requiring timing • Develop table Frank Lenkszus Advanced Photon Source

  28. Results of 1/17/2006 FERMI ILC RF and Controls Meeting • LLRF LO to be 52 MHz (1.3GHz/25) • LLRF ADC sampling frequency 86.667 MHz (1.3GHz/15) • 2% loss in Luminosity is driving Bunch Compressor specs. • Bunch compressor (BC) requires a separate rf spec (0.03 deg, 0.08%) • Rest of the system: • (+/-)0.5% energy error – brick wall limit! • 0.5 deg, 0.5% uncorrelated • 0.1 deg, 0.03% correlated • For MO/phase reference distribution/reconstruction and no beam (pilot bunch) spec is • +/- 0.5 degrees rms (1 psec @1.3GHz) over 15 km over “long” time scale • Beam based feedback (from cavity) will be used to stabilize locally distributed phase reference to the beam. • Fermilab ILC Beam Test Facility Spec: • Rf specs for three cryomodules (24 cavities) powered by a single Klystron: 0.5%, 0.5 degree rms long term • Timing distribution jitter: 1 ps rms Frank Lenkszus Advanced Photon Source

  29. References • “First Generation of Optical Fiber Phase Reference Distribution System for TESLA”, Krzysztof, C., et al, TELSA Report 2005-08 • “A High Stability , Low Noise RF Distribution System”, Frisch, J., et al, Proceedings of 2001 PAC, Chicago, pp 816 – 818 • “R&D for the ILC Phase/Timing Distribution System”, Frisch, J. 10/20/04 • Larsen, R. S., Technical Systems Configurations – Electrical Subsystem: Instrumentation – Timing, Rev. 1, March 23, 2001 • “Basic Timing Requirements for TELSA”, Kriens, W. TELSA Report • “Some Timing Aspects for ILC”, Ehrlichmann, H, DESY, Presented at GDE Freascati, December 2005. Frank Lenkszus Advanced Photon Source

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