Low Level RF Status Outline Overview showing hardware instances Refresher – status at time of last review Progress since last review Top level LLRF GUI System performance and reliability Near term (next 1-2 months) tasks Far term (> 2 months) tasks

Refresher – status at time of last review As of October 2006: Several instances of LLRF Phase and Amplitude Detectors (PADs) and several instances of LLRF Phase and Amplitude Controllers (PACs) existed LLRF VME crate and powerpc were in-house Timing hardware for LLRF VME was in-house All algorithms for the different flavors of PADs were written and one was tested in both the lab and gallery (details in Appendix)

Progress since last review LLRF hardware installation complete for sectors 20 and 21 Eight feedback loops have been commissioned. Top level GUI shown on slide 5. Loops control: phase and amplitude of S-band klystrons 20-5, 20-6, 20-7, 20-8, 21-1 and X-band klystron 21-2. GUIs on slides 7-9 show 21-1 loop laser phase. GUI shown on slide 9 gun temperature. GUI shown on slide 10 Diagnostics PAD for klystron 21-2 installed System uses save and restore tool to recover its configuration at boot System uses bootp to determine IOCs network parameters from host. No locally stored values.

Laser Stability: FB off vs on Beam Current Actual Laser Phase Feedback off Feedback on

Laser Oscillator RF Phase Stability LCLS Jitter Specification for 2 Seconds is 0.5 pS Feedback ON 20 Second Plot shows Phase Jitter 0.168 degrees 476MHz 1.0 pS Feedback ON 20 Second Plot shows Phase Jitter 0.163 degrees 476MHz 0.98 pS Short Term RF Jitter Specification for Laser Oscillator are not met. Needs work. No complaints from physicists. Photodetector is possible jitter source. Phase cavity may solve this.

RF Gun RF Stability LCLS Jitter Specification for 2 seconds is 0.1% amplitude and 0.1 degree Phase Feedback OFF 20 Second Plot shows Phase Jitter 0.145 degrees Amplitude Jitter 0.034% Feedback ON 20 Second Plot shows Phase Jitter 0.053 degrees Amplitude Jitter 0.04% Short Term RF Jitter Specification for the RF Gun are met. Need to work on reduction of flyers, adjust modulator thyratron.

L0A RF Stability LCLS Jitter Specification for 2 seconds is 0.14% amplitude and 0.14 degree Phase Feedback ON 20 Second Plot shows Phase Jitter 0.149 degrees Amplitude Jitter 0.22% Feedback ON 20 Second Plot shows Phase Jitter 0.157 degrees Amplitude Jitter 0.21% Short Term RF Jitter Specification for L0A are not met. Need to work on reducing 2-state variations.

L0B RF Stability LCLS Jitter Specification for 2 Seconds is 0.14% Amplitude and 0.14 degree Phase Feedback ON 20 Second Plot shows Phase Jitter 0.043 degrees Amplitude Jitter 0.022% Feedback ON 20 Second Plot shows Phase Jitter 0.043 degrees Amplitude Jitter 0.024% Short Term RF Jitter Specification for L0B are well Exceeded. This is as good as it gets – Don’t tell Physicists or they will expect it.

L1S RF Stability LCLS Jitter Specification for 2 Seconds is 0.14% Amplitude and 0.14 degree Phase Feedback ON 20 Second Plot shows Phase Jitter 0.095 degrees Amplitude Jitter 0.042% Feedback ON 20 Second Plot shows Phase Jitter 0.104 degrees Amplitude Jitter 0.043% Short Term RF Jitter Specification for L1S are met.

L1X RF Stability LCLS Jitter Specification for 2 Seconds is 0.25% Amplitude and 0.5 degree Phase Feedback ON 20 Second Plot shows Phase Jitter 1.28 degrees Amplitude Jitter 0.63% Feedback ON 20 Second Plot shows Phase Jitter 1.18 degrees Amplitude Jitter 0.62% Short Term RF Jitter Specification for L1X are not met. Needs work.

TCav RF Stability LCLS Jitter Specification for 2 Seconds is 1.0 degree Phase Feedback ON 20 Second Plot shows Phase Jitter 0.102 degrees Amplitude Jitter 0.011% Feedback ON 20 Second Plot shows Phase Jitter 0.149 degrees Amplitude Jitter 0.017% Short Term RF Jitter Specification for TCav are met. Need to work on reduction of flyers, adjust modulator thyratron.

Near term (in next 1-2 months) tasks Beam synchronous data acquisition (BSA) on phase and amplitudes SLC-aware (after BSA complete) Access security – define and implement Alarm handler configuration definition Klystron diagnostic PADs (20-5, 20-6, 20-7, 20-8 and 21-1) Software configuration adaptation to project standards (evolving) re: version control, tagging, layout, nodename hierarchy for startup files

Far term (> 2 months) tasks Sector 24 PAC, TCav PADs and PAC Sector 29 PAC Sector 30 PAC Switch PADs and PACs to talk to VME over private network Switch PADs to use second ethernet port to send whole waveform (will allow phase and amplitudes for EACH point in sample) HPRF

Appendix

PAD Software Different LLRF apps need different calculations There are 5 different algorithms: AVG+STD – calculate average I and Q and variance of I and Q RF WF – calculate average I and Q WF – calculate average of sample RF WF2 – calculate average I and Q of two samples IQ Cal – send 64K raw data waveform Each channel on a PAD can run a different algorithm with its own sample size and offset Each PAD can run in CALIBRATION or RUNNING mode, which use different algorithms

PAC Software PACs can run in either CALIBRATING or RUNNING mode. A state machine keeps track. If CALIBRATING, calibration waveforms are loaded into FPGA and I and Q gains and offsets can be adjusted. If RUNNING, I and Q gains and offsets are fixed, operational waveforms are loaded into FPGA and I and Q adjustments can be applied at the operational frequency.

VME Software Generic Feedback algorithm: Phase and amplitude are calculated from I and Q averages from each channel of the PAD Phases are corrected by phase offset correction Amplitudes are corrected by amplitude power correction Phase and amplitudes are weighted by configurable weighting factors to determine one average phase and amplitude Pavg=(P0*PWT0 + P1*PWT1 + P2*PWT2 + P3*PWT3)/4*(ΣPWTi) Aavg=(A0*AWT0 + A1*AWT1 + A2*AWT2 + A3*AWT3)/4*(ΣAWTi) Local or global feedback corrections are applied (0 < A <= 1) Pcor = A(Pdes – Pact) + (1-A)Pcorn-1 Pcorn+1 = A(Pdes n+1 – Pactn+1) + (1-A)Pcorn For amplitude, (Pdes – Pact) is replaced by Pdes/Pact Corrected phase and amplitude is converted to I and Q Corrected I and Q values are sent to PAC

Local feedback

VME Software Beam Phasing Cavity algorithm (for Laser Timing): Two sets of I and Q averages arrive (since there are two windows of interest) Phase1 is calculated from I1 and Q1 Phase2 is calculated from I2 and Q2 Measured beam phase is the y-intercept of the equation to the line of phase as a function of FIFO position Frequency is the slope of the line Amplitude is calculated from I1 and Q1 (only) Phase is corrected by phase offset correction Amplitude is corrected by amplitude power correction Local feedback corrections are applied Corrected phase and amplitude is converted to I and Q Corrected I and Q values are sent to laser PAC

Beam Phase Cavity: calculation of freqency and phase from a line through 2 points

VME Software Other calculations For RF Reference Distribution Phase and amplitude are calculated from I and Q averages from each channel of the PAD Phases are corrected by phase offset correction Amplitudes are corrected by amplitude power correction Standard deviation of I and Q is calculated from I and Q variances from each channel of the PAD

Host Applications Generic Distribution System PAC PAD Testing Correlation plots Calibration of power levels using beam energy Distribution System Rotate Phase 360 degrees Monitor Phase Errors in Dividers Correct Divider Phase Errors PAC Calibration Mode Operation Generate and Load Waveforms Panels for Phase and Amplitude Adjustment PAD Testing Crosstalk, SNR, Noise Floor Sine Wave Histogram Panels for Phase and Amplitude Monitoring Local Feedback Control Panels

Status of Documentation + Reviews All documentation and reviews are accessible from LLRFhomepage Recent milestones: LLRF Control Design Specification This Engineering Specification Document was signed off by Project Office on 9/27/2006. LLRF Final Design Review This review was held on 9/19/2006. The scope of the review covered: RF Distribution Reference System for Injector Commissioning RF System for Injector Commissioning PAD PAC VME These were the goals given to the committee last September: Injector RF turn on is January 3, 2007. The designs of the prototype PADs and PACs have been built and tested. Fabrication is scheduled for October, 2006. Please review analysis of test data and the proposed design and comment on the proposed systems' ability to meet LCLS specifications. Review our test plans and suggest improvements

LCLS New Reference System Lab Measurements Lab Tests Show Reference System Noise Levels Meet All LCLS Requirements 2856MHz = 70fSrms 2830.5MHz = 70fSrms 25.5MHz = 2pSrms 102MHz = 2pSrms 2856MHz : 22fSrms 10Hz to 10MHz 2830.5MHz : 22fSrms 10Hz to 10MHz John Byrd - LBNL 25.5MHz : 152fSrms 10Hz to 1MHz 102MHz : 281fSrms 10Hz to 10MHz

SLAC Linac RF – New Control The new control system will tie in to the IPA Chassis with 800W of drive power available. The RF Reference will be from the new RF reference system. Solid State Sub-Booster PAC I and Q will be controlled by the PAC chassis, running 16bit DACs at 102MHz. Waveforms to the DACs will be set in an FPGA through a microcontroller running EPICS on RTEMS. Existing System

Linac 21-1 Test Set-up Power Coupled out from 476MHz MDL drives a 476MHz Amplifier which feeds a 6X Multiplier from 476MHz to 2856MHz. The 2856MHz out drives both the LO generator and the PAC. The 2830.5MHz LO and 102MHz CLK Generator supplies the LO and CLK to the PAD. A CLK output of the PAD drives the PAC CLK. The PAC output drives the SSSB. The SSSB drives the existing IPA chassis The klystron output coupler is used to measure phase and amplitude with the new PAD.

Linac 21-1 Test Results Tests were done in the gallery with no temperature regulation on cables. Average RMS value of 2 second sliding average is 0.068 degrees. Exponential Smoothing Yields the Following Results. Lowest noise is with a time constant of about 2 points.