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Safety First and Second and Third…..to Infinity

Linac Coherent Light Source (LCLS) LLRF Preliminary Design Review LLRF Monitor and Control System September 26, 2005 Ron Akre. Safety First and Second and Third…..to Infinity. Hazards in the LLRF system

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Safety First and Second and Third…..to Infinity

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  1. Linac Coherent Light Source (LCLS) LLRF Preliminary Design ReviewLLRF Monitor and Control SystemSeptember 26, 2005Ron Akre

  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 • Training, do not disconnect cables and stick them in your eye. This is true even if they don’t have RF on them. • Do not use your tongue to test for RF • 110VAC Connector • Hazards - Shock • Mitigation - Don’t touch conductors when plugging into outlet.

  3. LCLS Layout P. Emma

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

  5. X- X-band LCLS Machine Stability Tolerance Budget Lowest Noise Floor Requirement 0.5deg X-Band = 125fS Structure Fill time = 100nS Noise floor = -108dBc/Hz @ 11GHz 5MHz 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

  6. Bandwidth of S-Band System • Upper Frequency Limit – 10MHz • Beam seen due to structure fill time ~ 1.2MHz • Structure RF Bandwidth ~ 16MHz • 5045 Klystron ~ 10MHz • Lower Frequency Limit – 100kHz • Fill time of SLED Cavity = 3.5uS about 100kHz • Laser – Needs to be measured ~ 100kHz

  7. Noise Levels • RF Reference Noise Floor • Oscillator -148dBc/Hz SSB at 2856MHz • RF -138dBc/Hz SSB at 2856MHz • 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 119MSPS 8.5MHz

  8. RF Control and Monitor Points Summary • RF Gun 1 Klystron 3 RF monitors • Beam Phase Cavity 1 IQ modulator 1 RF monitor • L0-A Accelerator 1 Klystron 2 RF monitors • L0-B Accelerator 1 Klystron 2 RF monitors • L0-T Transverse Accelerator 1 Klystron 2 RF monitors • L1-S Station 21-1 B, C, and D accelerators 1 Klystron 4 RF monitors • L1-X X-Band accelerator X-Band • S25-Tcav 1 Klystron 2 RF monitors • S24-1, 2, & 3 Feedback 3 Klystrons • S29 and S30 Feedback 2 IQ modulators 476MHz • Totals 2856MHz 10 modulators 16 monitors

  9. RF Monitor • LO 2830.5MHz : RF 2856MHz • IF 25.5MHz (8.5MHz x 3 in sync with timing fiducial) • Double-Balanced Mixer • Mixer IF to Low Pass Filter and Amp • Amp output to ADC (119MSPS or 102MSPS)?

  10. 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

  11. Status • Monitor Controller Board (J. Gold) • Single channel ADS5500 tested to specifications • Four channel ADS5500 board in layout • RF Monitor Board in preliminary design (H. Schwarz, B.Hong) • Control Boards (J. Olsen) • Fast Control Board in design • Slow control board not started • RF Control Board in preliminary design (H. Schwarz, B. Hong) • Software (D. Kotturi) • EPICS on RTEMS done • Drivers • Algorithms • Initial Testing – May 2005 • System Completion - December 2005

  12. 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.

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