Beam Position Charge Monitors LCLS Lehman Review July
Beam Position & Charge Monitors LCLS Lehman Review July 11, 2007 BPM Pickup Types Striplines Resonant Cavities (in undulator) Requirements / Specifications System overview Status July 11, 2007 Beam Position & Charge Monitors 1 Steve Smith ssmith@slac. stanford. edu
Requirements Full document: July 11, 2007 Beam Position & Charge Monitors 2 Steve Smith ssmith@slac. stanford. edu
Last Review Had just decided on a digitizer Commercial VME module did not perform Switched to 4 channel, 16 -bit, 130 Msample/sec digitizer developed for LCLS LLRF Packaging Throw in a box with BPM analog front end Schedule concerns: July 11, 2007 Beam Position & Charge Monitors 3 Steve Smith ssmith@slac. stanford. edu
Injector BPMs • 23 Stripline BPMs • 19 in injector • 1 in gun spectrometer • 3 in 135 Me. V spectrometer Installed and commissioned in early April • • just ahead of beam • Used to establish 1 st beam through injector July 11, 2007 Beam Position & Charge Monitors 4 Steve Smith ssmith@slac. stanford. edu
BPM Processor July 11, 2007 Beam Position & Charge Monitors 5 Steve Smith ssmith@slac. stanford. edu
July 11, 2007 Beam Position & Charge Monitors 6 Steve Smith BPM and Timing Racks ssmith@slac. stanford. edu
BPM Performance Take data synchronized pulse-by-pulse Use linear prediction of each BPM from adjacent BPMS Example: Compare bunch charge pulse 300 pulses 17 BPMs Average rms/mean 0. 0007 May include pulse -pulse variation in losses July 11, 2007 Beam Position & Charge Monitors 7 Steve Smith ssmith@slac. stanford. edu
Performance Predict BPM position reading from linear fit to adjacent BPMs (Model-independent) July 11, 2007 8 300 machine pulses Beam Position & Charge Monitors Effective beam charge 0. 35 n. C sx = 2. 5 microns Steve Smith sy = 1. 7 microns ssmith@slac. stanford. edu
BPM Performance Q~ 200 p. C Resolution requirement is 10 microns for the small aperture BPMs Meets resolution requirements July 11, 2007 Beam Position & Charge Monitors 9 Steve Smith ssmith@slac. stanford. edu
Cavity Position Monitors July 11, 2007 Beam Position & Charge Monitors 10 Steve Smith ssmith@slac. stanford. edu
LTU and Undulator BPM System Specification Parameter Specification Limit Condition Resolution < 1 m 0. 2 – 1. 0 n. C +/- 1 mm range Offset Stability < +/- 1 m 1 hour +/- 1 mm range 20. 0 +/- 0. 56 Celsius Offset Stability < +/- 3 m 24 hours +/- 1 mm range 20. 0 +/- 0. 56 Celsius Gain Error < +/- 10 % +/- 1 mm range 20. 0 +/- 0. 56 Celsius Dynamic Range, Position +/- 1 mm 10 mm diameter vacuum chamber Dynamic Range, Intensity > 14 d. B PC Gun 0. 2 – 1. 0 n. C July 11, 2007 Beam Position & Charge Monitors 11 Steve Smith ssmith@slac. stanford. edu
X-Band Cavity BPM Development Five X-Band Cavity BPM built and tested Two qualified vendors for machined parts Brazing procedure optimized to preserve tune Tuning and testing procedures generated July 11, 2007 Beam Position & Charge Monitors 12 Steve Smith ssmith@slac. stanford. edu
BPM Simulations Cavity BPMs simulated in Microwave Studio, HFSS and Mafia Test data indicates good agreement between simulated model and measured BPMs Port 1 Port 4 YPort 2 Mono pole mode XPort Vertical dipole mode Port 3 July 11, 2007 Beam Position & Charge Monitors 13 Steve Smith ssmith@slac. stanford. edu
Cavity BPM Development R&D phase of near completion Testing phase II expected completed by end of July Entering production phase July 11, 2007 Beam Position & Charge Monitors 14 Steve Smith ssmith@slac. stanford. edu
Undulator System Layout Beam X-band receiver LRU July 11, 2007 Beam Position & Charge Monitors 15 Steve Smith ssmith@slac. stanford. edu
Receiver Development X-Band down-converter developed from existing Miteq product Modified to meet LCLS requirements 3 channel receiver with common LO 4 first article packaged receivers delivered and presently being tested July 11, 2007 Beam Position & Charge Monitors 16 Steve Smith ssmith@slac. stanford. edu
X-Band Receiver System Features Input RF Power Surge Limiters Input DC power regulation High/Low gain feature (28/0 d. B) to extend dynamic range Integrated self-test Multi-mode operation with phase locked LO to control system or free-run mode July 11, 2007 Beam Position & Charge Monitors 17 Steve Smith ssmith@slac. stanford. edu
BPM Testing Non-Vacuum Single BPM cold test unit complete 04/06 (Phase I) test in APS Injector Test Stand complete 09/06 (Phase II) 3 -BPM test in APS LEUTL Complete test matrix to prove compliance to specification Testing phase II expected completed by end of July 11, 2007 Beam Position & Charge Monitors 18 Steve Smith ssmith@slac. stanford. edu
LEUTL 3 -BPM Test PC gun installed and LEUTL tunnel commissioned PC gun beam 325 Me. V (400 p. C) to dump 33 Hor. and 23 Vert. micron normalized emittance Compressed beam 1 ps bunch length July 11, 2007 Beam Position & Charge Monitors 19 Steve Smith ssmith@slac. stanford. edu
In-Tunnel Progress 2 -axis translation stage installed and tested provide sub-micron controllable horizontal and vertical motion Multiple experiments presently conducted to verify operation Testing ongoing July 11, 2007 Beam Position & Charge Monitors 20 Steve Smith ssmith@slac. stanford. edu
3 BPM Test June 20 data Had trouble getting acquisition synchronous Took 2 calibration scans One in X, one in Y Move BPMs in 100 micron steps Use to establish phase amplitude scale offset of BPM signal Then mover ran away ending run (Very) Preliminary results look good July 11, 2007 Beam Position & Charge Monitors 21 Steve Smith ssmith@slac. stanford. edu
X Scan Mover X-scan Steps of 100 microns Predict BPM 2 X from BPMS 1 & 3 Resolution ~8 microns July 11, 2007 Beam Position & Charge Monitors 22 Steve Smith ssmith@slac. stanford. edu
Y Scan Mover Y-scan Steps of 100 microns Predict BPM 2 Y from BPMS 1 & 3 Resolution ~12 microns July 11, 2007 Beam Position & Charge Monitors 23 Steve Smith ssmith@slac. stanford. edu
Summary X-Band Cavity BPM Development Nearly Complete 4 Cavity BPM built and tested Machining and braze critical tasks identified BPM phase ll testing expected complete July 07 Production procurement ongoing Receiver Prototype Development Nearly Complete First 4 prototypes assembled and tested with good results 3 -BPM testing prototypes incorporate receiver, local oscillator and filter first article packaging Production procurement ongoing Test Qualification Collaborating with SLAC to test and qualify Qualifying system with the same ADC (PAD) as SLAC LINAC BPM upgrade Testing is ongoing at this time with promising results Entering Production phase July 11, 2007 Beam Position & Charge Monitors 24 Steve Smith ssmith@slac. stanford. edu
Charge Monitors July 11, 2007 Beam Position & Charge Monitors 25 Steve Smith ssmith@slac. stanford. edu
Charge Monitors S 2 Channel 4 Chan Fast Digitizer Access Channel Access Raw Data Toroids 5 -8 trig Analog Charge Values July 11, 2007 Beam Position & Charge Monitors LNA Baseline Int#1 + - S 4 S 3 MPS Signals S/H Beam Pulse S 5 Int#2 to Fast Acquisition Board for waveform capture MPS Acromag IP 330 16 channel, 16 bit 8 u. S conv. time 26 Signal amplitude Toroid/Cal Cables Toroids 1 -4 IOC EVR ADC LMR-400 x 8 S 1 EVR Beam Pulse Int#2 #1 Dark Current t 1 t 2 t 3 t 4 t 5 Steve Smith ssmith@slac. stanford. edu t 6
Charge Monitoring Injector: 6 toroids, 2 Faraday cups All installed Toroid IM 01 output shorted by vacuum bolt Replace when we can break vacuum at gun Faraday cup FC 01 disabled when first inserted July 11, 2007 Beam Position & Charge Monitors 27 Steve Smith ssmith@slac. stanford. edu
Commisioning Toroid amplifier input bandwidth too high Decrease bandwidth seen by first amp Present bandwidth not useful Early indication is that a simple RC filter reduces jitter Presently don’t trust online calibration Use fixed, bench calibration numbers Use online cal for status of health of electronics July 11, 2007 Beam Position & Charge Monitors 28 Steve Smith ssmith@slac. stanford. edu
Toroid System Next Phase Complete Injector installation/commissioning REmianing in LCLS: 7 more toroids in BC 2 LTU Undulator Dump All toroids built Baked Electrically tested On shelf BC 2 / BTH west installation design in progress July 11, 2007 Beam Position & Charge Monitors 29 Steve Smith ssmith@slac. stanford. edu
Backup Slides July 11, 2007 Beam Position & Charge Monitors 30 Steve Smith ssmith@slac. stanford. edu
Beam Position Monitor System Analog Frontend Version Three July 11, 2007 Beam Position & Charge Monitors 31 Steve Smith ssmith@slac. stanford. edu
Calibration Calibrate through BPM Via stripline-stripline coupling Performance not yet verified July 11, 2007 Beam Position & Charge Monitors 32 Steve Smith ssmith@slac. stanford. edu
Linearity Measured IP 3 of BPM signal path found IP 3 within a few d. B of calculation Bench test of apparent position vs. amplitude looks good Test consists of 15 k. Hz 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 m. A 140 m. A Reduce bandwidth of first filter, raise that of second filter Narrowband filter before 2 nd gain stage July 11, 2007 Beam Position & Charge Monitors 33 Steve Smith ssmith@slac. stanford. edu
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