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LCLS LLRF System Safety and Upgrade Status

Learn about hazards and mitigation measures in the LLRF system, as well as the status of upgrades for Linac Sector 0 and Sector 20. Details on RF components, control systems, and monitoring. Stay informed on the latest developments.

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LCLS LLRF System Safety and Upgrade Status

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  1. Linac Coherent Light Source (LCLS) Low Level RF SystemInjector Turn-on December 2006April 20, 2006

  2. Safety First and Second and Third…..to Infinity • Hazards in the LLRF system • RF 1kW at 120Hz at 5uS = 0.6 Watts average, • 2 Watt average amps at 2856MHz, • 60W average amps at 476MHz • Hazards – RF Burns • Mitigation – Avoid contact with center conductor of energized connectors. All employees working with LLRF systems are required to have the proper training. • 110VAC Connector • Hazards - Shock • Mitigation - Don’t touch conductors when plugging into outlet. • All chassis are inspected by UL trained inspector.

  3. Scope of Work – Injector Turn-on • Linac Sector 0 RF Upgrade WBS 1.02.04.03.01 • All 3 RF Chassis completed and Installed • Control Module ready for test – John Dusatko • Sector 20 RF distribution system WBS 1.02.04.03.02 • Phase and Amplitude Controllers (PAC) – 6 units in Design • Phase and Amplitude Detectors (PAD) – 1 unit in Design • Phased Locked Oscillator – Use SPPS unit for Turn On • LO Generator – Design 90% Complete and tested • Multiplier – 476MHz to 2856MHz – Complete • 4 distribution chassis - Complete • Laser Phase Measurement – in Design – not required for turn on • LLRF Control and Monitor System WBS 1.02.04.03.03 • 1 kW Solid State S-Band Amplifiers – 5 units – in Fab, 2 done • PAD – 12 units as above in design • PAC – 6 units as above in design • Bunch Length Monitor Interface – awaiting Specs • Beam Phase Cavity WBS 1.02.04.03.04 • Will use single channel of PAD Chassis • Pill box cavity with 2 probes and 4 tuners - Complete next month

  4. LCLS Layout P. Emma

  5. LLRF Control system spans Sector 20 off axis injector to beyond Sector 30

  6. 0.50 X- X-band LCLS RF Jitter Tolerance Budget Lowest Noise Floor Requirement 0.5deg X-Band = 125fS Structure Fill time = 100nS Noise floor = -111dBc/Hz @ 11GHz 10MHz BW -134dBc/Hz @ 476MHz RMS tolerance budget for <12% rms peak-current jitter or <0.1% rms final e− energy jitter. All tolerances are rms levels and the voltage and phase tolerances per klystron for L2 and L3 are Nk larger, assuming uncorrelated errors, where Nk is the number of klystrons per linac. P. Emma

  7. Slow Drift Tolerance Limits (Top 4 rows for De/e < 5%, bottom 4 limited by feedback dynamic range) P. Emma, J, Wu (Tolerances are peak values, not rms) * for synchronization, this tolerance might be set to 1 ps (without arrival-time measurement)

  8. Linac Sector 0 RF Upgrade LCLS must be compatible with the existing linac operation including PEP timing shifts Master Oscillator is located 1.3 miles from LCLS Injector 1.3 Miles to LCLS Injector Measurements on January 20, 2006 at Sector 21 show 30fS rms jitter in a bandwidth from 10Hz to 10MHz PEP PHASE SHIFT ON MAIN DRIVE LINE MDL RF with TIMING Pulse – Sync to DR

  9. Linac Sector 0 RF Upgrade Status • New Low Noise Master Oscillator – Done • New Low Noise PEP Phase Shifter • RF Chassis – Done • Control Chassis – In Test • New Low Noise Master Amplifier – Done • Main Drive Line Coupler in Sector 21 – Done • Measurements • Noise floor on 476MHz of -156dBc/Hz • Integrated jitter from 10Hz to 10MHz of 30fS

  10. Sector 20 RF Distribution Phase Critical Cables Laser <140ft < 700fSpp Gun < 100ft < 400fSpp

  11. Sector 20 RF Distribution System Status • Phase Locked Oscillator – 476MHz • Initial Turn On use SPPS Oscillator • May modify control to achieve better stability during 2007 • LO Generator – 2830.5MHz • Design complete – Prototype tested – 25MHz SSB modulator board done • 2856MHz IQ Modulator prototype near completion • Multipliers - 476MHz to 2856MHz – Done • Phase and Amplitude Control (PAC) Unit • In Design – IQ Modulators and Amplifiers selected – See Next Section • Phase and Amplitude Detector (PAD) Unit • In Design – Testing Mixers, Amplifiers, Filters – See Next Section • Amplifiers – not ordered yet • Laser Phase Measurement System – Design Started

  12. LLRF Control System • Distributed Control System • Microcontroller based IOC Control and Detector Modules • Ethernet Switch • Central Feedback Computer

  13. LLRF Control and Monitor System Klystron Station

  14. LLRF Control and Monitor System Status • 1 kW Solid State S-Band Amplifiers – 5 units • 1kW amplifier modules currently in test • Existing amplifier support design under review • Phase and Amplitude Detectors – 11 dual chan units • Preliminary Design Complete • Evaluating amplifiers, mixers, and filters • Phase and Amplitude Controllers – 6 single chan units • Preliminary design complete • Evaluating mixers and amplifiers • Bunch Length Monitor Interface • Need Specifications

  15. Beam Phase Cavity Status Measurement of beam phase to RF reference phase. The result will be used to correct timing of laser to RF reference. Cavity is located between L0A and L0B. • Electronics will use single channel of PAD Chassis • Pill box cavity with 2 probes and 4 tuners • Cavity Electronics will use single channel of RF Monitor • Cavity in fabrication • Complete – May 2006 • Bake – June 2006

  16. Controls Engineering Requirements • When beam is present, control will be done by beam-based longitudinal feedback (except for T-cavs); when beam is absent, control will be done by local phase and amplitude controller (PAC) • Adhere to LCLS Controls Group standards: RTEMS, EPICS, Channel Access protocol • Ref: Why RTEMS? Study of open source real-time OS • Begin RF processing of high-powered structures June 2006

  17. External Interfaces • LLRF to LCLS global control system • PVs available for edm screens, archiving, etc over controls network • LLRF VME to beam-based longitudinal feedback • from feedback: phase and amplitude corrections at 120 Hz over private ethernet • from LLRF: phase and amplitude values • (internal) LLRF VME to LLRF microcontrollers • from VME: triggers, corrected phase and amplitude • from microcontrollers: phase and amplitude averaged values at 120 Hz, raw phase and amplitude values for diagnostics

  18. Sector 20 PAC and PAD Control • VME IOC • Ethernet Switch • Arcturus Coldfire • 13 PADs • FIFO • ADC • 13 PACs • FPGA • DAC

  19. EPICS PANELS • Single Pulse Diagnostic Panels for PADs are Running • Remaining Software • History Buffer Select PVs • Multi pulse data analysis, correlation plots • Local RF Feedback loops • Links to global Feedback loops

  20. RF Status Summary • Linac New Low Noise Source – RF components installed, Controls Feb06 • RF Distribution – Prototyping underway (R. Akre, B.Hong, H. Schwarz) • Monitor Controller Board (J. Gold, R. Akre, Till Straumann) • Single channel prototype for ADS5500 tested to specifications • Four channel ADS5500 board – layout complete (SNR 70dBFS) • Switched to LTC2208 16bit 130MSPS ADC (Prototype in test) (SNR 77dBFS) • RF Monitor Board in preliminary design (H. Schwarz, B.Hong) • Testing mixers • Control Boards (J. Olsen) • Fast Control Board – All but slow ADCs for temp and voltages tested and low level drivers written • Slow control board – use fast board • RF Control Board in preliminary design (H. Schwarz, B. Hong) • Software (D. Kotturi, Till Straumann) • EPICS on RTEMS on Microcontroller done • Drivers – data collection interrupt routine done • Algorithms – PAD 90% complete PAC in progress • Calibration routines – Need specifications • Collision free Ethernet

  21. LLRF Schedule • RF Distribution Design Complete May 2006 • RF Hut Distribution System installed August 2006 • PAC design Complete June 2006 • PAD design Complete July 2006 • PAC and PAD minimal operational software complete • Ethernet testing with multiple PACs and PADs??? • Single S-Band station – hardware installed Sept 2006 • 4 other S-Band Stations – November 2006 • Feedback software interfacing??? • Test and debug with Klystrons On – December 2006 • X-Band Station January 2007

  22. End of LLRF RF TalkBackup for RF TalkMostly Correct

  23. DESIGN PHILOSOPHY • Reliability is inversely proportional to the number of connectors. • Stability is inversely proportional to the number of connectors. • Measurement accuracy is inversely proportional to the number of connectors and the amount of Teflon,which is typically found in connectors. • Cost of maintenance is proportional to the number of connectors.

  24. Electro-Optical Sampling Timing Jitter (20 Shots) 200 mm thick ZnTe crystal Single-Shot e- <300 fs Ti:Sapphire laser e- temporal information is encoded on transverse profile of laser beam 170 fs rms Adrian Cavalieri et al., U. Mich.

  25. MPS – PPS Issues Addressed by Controls Group Not Reviewed Here • Vacuum • New vacuum system summary to be fed to each klystron existing MKSU. • PPS System • Injector modulators will be interlocked by Injector PPS system. • PPS requirements for radiation from the injector transverse accelerator needs to be determined. Radiation levels will be measured during testing in the Klystron Test Lab – Feb 06.

  26. Bandwidth of S-Band System • Upper Frequency Limit – 10MHz • Beam-RF interaction BW due to structure fill time • < 1.5MHz S-Band Accelerators and Gun • ~10MHz X-Band and S-Band T Cav • Structure RF Bandwidth ~ 16MHz • 5045 Klystron ~ 10MHz • Lower Frequency Limit – 10kHz • Fill time of SLED Cavity = 3.5uS about 100kHz • Laser – Needs to be measured ~ 10kHz

  27. Noise Levels • RF Reference Single Side Band (SSB) Noise Floor • 2856MHz RF Distribution -144dBc/Hz • -174dBc/Hz @ 119MHz (24x = +28dB +2 for multiplier) • 2830.5MHz Local Oscillator -138dBc/Hz • Integrated Noise • -138dBc/Hz at 10MHz = -65dBc = 32fS rms • SNR = 65dB for phase noise • Added noise from MIXER (LO noise same as RF) • SNR of 62dB • ADC noise levels • SNR of 70dB – 14bit ADS5500 at 102MSPS

  28. Phase Noise – Linac Sector 0 OLD MASTER OSCILLATOR -133dBc/Hz at 476MHz 340fSrms jitter in 10MHz BW NEW MASTER OSCILLATOR -153dBc/Hz at 476 MHz 34fSrms jitter in 10MHz BW Integrated Noise - Timing Jitter fs rms Integral end 5MHz 10kHz Integral start 1M 100k 10k 1k 100 10 Aug 17, 2004 Sector 30 27 30 33 38 75 82 Jan 20, 2006 Sector 21 15 19 20 20 8 17

  29. Sector 20 RF Distribution Cable Errors Temperature Coefficient of 2.8ppm/ºF and Cable length is 1200ºS/ft All Cables except LASER are less than 100ft Distances feet and errors in degrees S total range RF Hut Down Linac Wall Injector Total Unit Ft degS ft degS ft degS ft degS ft degS DegS Laser 8 0.054 25 0.017 10 0.014 10 0.007 85 0.58 0.68 Gun 8 0.054 25 0.017 10 0.014 10 0.007 40 0.27 0.37 L0-A 8 0.054 25 0.017 10 0.014 10 0.007 30 0.21 0.31 B Phas 8 0.054 25 0.017 10 0.014 10 0.007 20 0.14 0.24 L0-B 8 0.054 25 0.017 10 0.014 10 0.007 20 0.14 0.24 L0-T 8 0.054 25 0.017 10 0.014 10 0.007 10 0.07 0.17 L1-S 8 0.054 25 0.017 50 0.068 0.14 L1-X 8 0.054 25 0.017 60 0.081 0.16 Temperature Variations: RF Hut ±1ºF : Penetration ±0.1ºF : Linac : ±0.2ºF Shield Wall ±0.1ºF : Injector ±1ºF

  30. RF System Topology / Specifications

  31. RF Monitor Signal Counts ADC Chan CntChassis Count/Location • Distribution (5~2850MHz, 4<500MHz) 4 1Hut • RF Gun 9 1Kly 1.5Hut • Beam Phase Cavity 2 0.5Hut • L0-A Accelerator 4 1Kly 0.5Hut • L0-B Accelerator 4 1Kly 0.5Hut • L0-T Transverse Accelerator 4 1Kly 0.5Hut • L1-S Station 21-1 B, C, and D Acc 6 1Kly 1.0Hut • L1-X X-Band accelerator X-Band 5 1Kly 0.5Hut • S25-Tcav 4 1Kly • S24-1, 2, & 3 Feedback 0 • S29 and S30 Feedback 0 • Total Chassis 7Kly 6Hut • Total into Hut IOC 12

  32. RF Control Signal Counts • Distribution (3~2850MHz, 3<500MHz) 6 IQ Mod • RF Gun 1 Klystron • Beam Phase Cavity 1 IQ mod • L0-A Accelerator 1 Klystron • L0-B Accelerator 1 Klystron • L0-T Transverse Accelerator 1 Klystron • L1-S Station 21-1 B, C, and D accelerators 1 Klystron • L1-X X-Band accelerator X-Band 1 IQ Mod • S25-Tcav 1 Klystron • S24-1, 2, & 3 Feedback 3 Klystrons • S29 and S30 Feedback 2 IQ modulators 476MHz • Total modulators 11 Fast 8 Slow 19 modulators • Totals at ~2856MHz 14 modulators • Total into Hut IOC 14 modulators

  33. LLRF Control and Monitor System • LLRF Control and Monitor System • 1 kW Solid State S-Band Amplifiers – 5 units • Phase and Amplitude Monitors – 12 units • Phase and Amplitude Controllers – 6 units • Bunch Length Monitor Interface – Need Specifications

  34. RF Control Required 13 Units Includes Distribution RF Control Module consist of the following: Input Coupler, IQ Modulator, Amplifier, Output Coupler Filters for I and Q inputs

  35. RF Monitor • Required 13 Chassis for Injector – Includes Distribution • LO 2830.5MHz : RF 2856MHz • IF 25.5MHz (8.5MHz x 3 in sync with timing fiducial) • Double-Balanced Mixer • Mixer IF to Amp and then Low Pass Filter • Filter output to ADC sampling at 102MSPS 2830.5MHz Local Osc. To ADC LTC2208 SNR = 77dBFS 102MSPS 2856MHz RF Signal

  36. 1 kW Solid State S-Band Amplifiers • Design Complete • Two Units on the Shelf • Modules in house – and tested • Support parts – Some parts in house • Power Supplies, relays, chassis on order

  37. SLAC Linac RF – New Control The new control system will tie in to the IPA Chassis with 1kW of drive power available. Reference will be from the existing phase reference line or the injector new RF reference I and Q will be controlled with a 16bit DAC running at 119MHz. Waveforms to the DAC will be set in an FPGA through a microcontroller running EPICS on RTEMS. Existing System

  38. Controls Talk

  39. LLRF Controls • Outline • Requirements • External Interfaces • Schedule • Date Needed • Prototype Completion Date • Hardware Order Date • Installation • Test Period • Design • Design Maturity (what reviews have been had) • State of Wiring Information • State of Prototype

  40. Requirements • At 120 Hz, meet phase/amp noise levels defined as: • 0.1% rms amplitude • 100 fs rms in S-band (fill time = 850 ns) • 125 fs rms in X-band (fill time = 100 ns) • All tolerances are rms levels and the voltage and phase tolerances per klystron for L2 and L3 are Nk larger, assuming uncorrelated errors, where Nk is the number of klystrons per linac (L2 has 28; L3 has 48)

  41. Engineering Requirements • When beam is present, control will be done by beam-based longitudinal feedback (except for T-cavs); when beam is absent, control will be done by local phase and amplitude controller (PAC) • Adhere to LCLS Controls Group standards: RTEMS, EPICS, Channel Access protocol • Ref: Why RTEMS? Study of open source real-time OS • Begin RF processing of high-powered structures May 20, 2006

  42. External Interfaces • LLRF to LCLS global control system • PVs available for edm screens, archiving, etc over controls network • LLRF VME to beam-based longitudinal feedback • from feedback: phase and amplitude corrections at 120 Hz over private ethernet • from LLRF: phase and amplitude values • (internal) LLRF VME to LLRF microcontrollers • from VME: triggers, corrected phase and amplitude • from microcontrollers: phase and amplitude averaged values at 120 Hz, raw phase and amplitude values for debug

  43. External Interfaces: Laser - Tcav

  44. External Interfaces: L2-L3

  45. Design • Design maturity (what reviews have been had): • RF/Timing Design, DOE Review, August 11, 2004 • Akre_FAC_Oct04_RF_Timing, FAC Review, October, 2004 • Low Level RF Controls Design, LCLS Week, January 25-27, 2005 • Low Level RF, Lehman Review, May 10-12, 2005 • LLRF Plans for Development and Testing of Controls, LCLS Week, July 21, 2005 • Low Level RF Design, Presentation for Controls Group, Sept. 13, 2005 • LLRF Preliminary Design review, SLAC, September 26, 2005 • LCLS LLRF Control System - Kotturi, LLRF Workshop, CERN, October 10-13, 2005 • LCLS LLRF System - Hong, LLRF Workshop, CERN, October 10-13, 2005 • LLRF and Beam-based Longitudinal Feedback Readiness - Kotturi/Akre, LCLS Week, SLAC, October 24-26, 2005 • LCLS Week LLRF and feedback - Kotturi/Allison, LCLS Week, SLAC, October 24-26, 2005 • LLRF, LCLS System Concept Review/Preliminary Design Review, SLAC, November 16-17, 2005 Comments • LLRF Beam Phase Cavity Preliminary Design review, SLAC, November 30, 2005 Docs at: http://www.slac.stanford.edu/grp/lcls/controls/global/subsystems/llrf • State of wiring: percent complete Captar input will be given at time of presentation • State of prototype: PAD (1 chan ADC) and PAC boards built (shown on next pages).Testing.

  46. PAD – the monitor board

  47. PAD – the monitor board

  48. PAC – the control board

  49. PAC – the control board

  50. Additional Slides • The following two pages show an overview of the LLRF control modules. From these diagrams, counts of module types, as well as function and location are seen.

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