Transcript BPM Update
Beam Position Monitors Facility Advisory Committee October 12, 2006 Action Items from previous review Requirements / Specifications System overview Status Schedule October 12, 2006 LCLS Facility Advisory Committee 1 S. Smith [email protected] Action Items from Previous FAC Decide on a Digitizer Echotek glitches, lockups, lack of progress Plan B Plan A: Select 4 channel PAD digitizer. Fix schedule Still schedule trouble Plan barely finishes on time No schedule contingency October 12, 2006 LCLS Facility Advisory Committee 2 S. Smith [email protected] PRD 1.1-314 Full document: October 12, 2006 LCLS Facility Advisory Committee 3 S. Smith [email protected] Beam Position Monitor System Analog Frontend Version Three Switchable Attenuators Band pass Low Noise Amplifier Amp Pad Band pass Amp Input To ADC Fc=140MHz 0dB NF=2.8dB 0dB NF=3.3dB BW=14MHz to Gain=20dB to Gain=15dB (was 20 MHz) 15dB IP3=40dBm 15dB IP3=40dBm October 12, 2006 LCLS Facility Advisory Committee 4 6 dB Fc=140MHz NF=3.3dB BW=6 MHz Gain=15dB IP3=40dBm S. Smith [email protected] Beam Test 100 machine pulses Effective beam charge 0.35 nC sy = 2.5 microns October 12, 2006 LCLS Facility Advisory Committee 5 S. Smith [email protected] Resolution vs. Charge 5mm @ 200pC Measured with beam in machine Tightest machine requirement: 5 micron resolution @ 200 pC Achieve 4 micron resolution @ 200 pC Resolution scales like 1/Q for the three measured bunch charges, as expected October 12, 2006 LCLS Facility Advisory Committee 30 6 400 S. Smith [email protected] Linearity Measured IP3 of BPM signal path found IP3 within a few dB of calculation Bench test of apparent position vs. amplitude looks good Test consists of 15 kHz AM of 140 MHz signal Results impeccable. But beam test shows big amplitude position modulation Discovered prototype not built to schematic Gain distribution wrong Fixed Took further steps: Raise amp idle current 90 mA 140 mA Reduce bandwidth of first filter, raise that of second filter Narrowband filter before 2nd gain stage October 12, 2006 LCLS Facility Advisory Committee 7 S. Smith [email protected] Status Prototype meets resolution requirement Stability not well established Long weekend test looks great But doesn’t apply controlled temperature cycles Attempt to resurrect CPE environmental chambers not successful Thermal cycle tests yet to be performed Proceeding with first article production October 12, 2006 LCLS Facility Advisory Committee 8 S. Smith [email protected] Calibration Calibrate through BPM Via stripline-stripline coupling Not prototyped October 12, 2006 LCLS Facility Advisory Committee 9 S. Smith [email protected] Schedule What should be done: (E.M. 9/20/2006) PCB layout – end of September - 29 ? PCB fabrication – one week – October 9 ? PCB assembling – one board here – October 13 Chassis layout – September 28 Panels punching and painting - early October buy the rest of the components – connectors, resistors, capacitors, etc. buy 23 chassis Write detailed test procedure October 12, 2006 LCLS Facility Advisory Committee 10 S. Smith [email protected] Software & Interface VME IOC EPICS PVs SLC - Aware EVR Archive FIFO Timing X,Y,TMIT Calib. Waveform->U,V,S Dedicated Ethernet PAD IOC AFE CTL Timing + Cal Data ADC Acq. diagnostic EPICS PVs AFE October 12, 2006 LCLS Facility Advisory Committee 11 S. Smith [email protected] BPM Controls Description User Interface Layer (EPICS, SLC-aware) VME IOC Converts raw waveforms into X,Y,TMIT and feeds them (timestamped) to SLC. Conversion parameters are Pvs Controls calibration PAD IOC Sends raw data upstream (dedicated ethernet) Diagnostic EPICS PVs October 12, 2006 LCLS Facility Advisory Committee 12 S. Smith [email protected] Software Functionality (Day 1) From SLC-aware IOC averaged BPM readings buffered acquisition EPICS raw waveforms conversion params. (raw position -> x,y) attenuator settings diagnostics October 12, 2006 LCLS Facility Advisory Committee 13 S. Smith [email protected] Functionality (Near Future) Calibration [some features may be present at day one; untested]. More sophisticated history buffers [other than SLC 'buffered acq'] Filtering of beam codes in EPICS Adjusting to beam charge in 'real-time' October 12, 2006 LCLS Facility Advisory Committee 14 S. Smith [email protected] Conclusions Good performance demonstrated Schedule critical October 12, 2006 LCLS Facility Advisory Committee 15 S. Smith [email protected]