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 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.

LCLS Layout P. Emma

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

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 X-band X- 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

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

Noise Levels RF Reference Noise Floor Integrated Noise 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

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

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)?

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

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

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.