Beam Position Monitor Developments at PSI

Transcription

1 Paul Scherrer Institut V. Schlott for the PSI Diagnostics Section Wir schaffen Wissen heute für morgen Beam Position Monitor Developments at PSI

2 Overview Motivation European XFEL BPM Systems SwissFEL BPM System SLS BPM and FOFB Upgrades Summary & Outlook

3 Acknowledgements The presentation summarizes the work from : Boris Keil Raphael Baldinger Carl Beard Robin Ditter Reinhold Kramert Waldemar Koprek Goran Marinkovic Markus Roggli Martin Rohrer Markus Stadler Daniel Treyer Many thanks also for the support from our colleagues at : DESY and CEA / Saclay / Irfu European XFEL in-kind contributions are funded by : Swiss State Secretary for Education, Research and Innovation (SERI)

4 Motivation: Large Scale Projects Swiss IK contribution to European XFEL (~ 470 systems from ): electronics for button, re-entrant cavity and cavity BPMs beam stabilization with fast intra bunch-train FB ( s latency) SwissFEL XFEL user facility at PSI (~ systems from ): BPM system (cavity BPMs) for all accelerator parts electronics platform (and firmware) for all other diagnostics systems SLS BPM system and FOFB upgrade (~ 150 systems from (2018)): renewal & upgrade of BPM electronics (improved resolution at higher BW) fast orbit feedback with higher correction bandwidth (> 200 Hz)

5 Main Specifications for European XFEL BPMs European XFEL (standard warm button BPMs for nc beam charge): position resolution: 50 m (rms) single bunch * / 10 m (rms) 1000 bunch average aperture size: 40.5 mm (round beam pipe) drift (hour / week): m / m European XFEL (undulator cavity BPMs for nc beam charge): position resolution: 1 m (rms) single bunch * / 0.2 m (rms) 1000 bunch average aperture size: 10 mm (round beam pipe) drift (hour): < 1 m European XFEL (transfer line (IBFB) cavity BPMs for nc beam charge): position resolution: 10 m (rms) single bunch * / 1 m (rms) 1000 bunch average aperture size: 40.5 mm (round beam pipe) drift (hour / week): < 6 m / 11 m * bunch spacing: 200 ns, up to 3000 bunches per 10 Hz rep. rate

6 Main Specifications for SwissFEL and SLS BPMs SwissFEL (standard / transfer line cavity BPMs for pc beam charge): position resolution: 5 m (rms) single bunch * (for ± 5 mm position range) aperture size: 16 mm (round beam pipe) drift (week): < 5 m SwissFEL (undulator cavity BPMs for pc beam charge): position resolution: 1 m (rms) single bunch * (for ± 1 mm position range) aperture size: 8 mm (round beam pipe) drift (week): < 1 m * bunch spacing: 28 ns (two 100 Hz rep. rate Swiss Light Source (storage ring (FOFB) BPMs for 400 ma beam current (top-up)): position resolution: < 100 nm 2 khz BW / m level for turn-by-turn aperture size: 65 mm (h) x 35 mm (v) drift (weeks): sub- m

7 Modular BPM / Diagnostics Platform Architecture E-XFEL / SwissFEL Cavity BPM Electronics (Simplified) 3-5GHz IQ LO RF Front-end ADC Gsps Mezzanine Common housing, fan, power supply Carrier board FPGA Virtex-5 FXT Control System New SLS BPM Electronics (Simplified) 500MHz ADC 0.1-5Gsps FPGA Virtex-5 FXT Control System RF Front-end Mezzanine Carrier board Common housing, fan, power supply

8 European XFEL Button BPM Electronics: RFFE Diode + S&H capacitor. Discharge: Automatic, or via external trigger Active temperature stabilization (several sensors + heaters) On-board test/calibration pulser simulates beam signal Finite-response chirp filter improves low-charge resolution Two modes: External trigger, or self-trigger (on beam signal)

9 European XFEL Button BPM Electronics: RFFE Pickup Signal Stretched by Chirp Filter RFFE output signal, mode1: Automatic S&H discharge by resistor (=nonstandard mode e.g. when external trigger is missing) RFFE output signal, mode2: S&H discharge by external trigger (=standard mode)

10 European XFEL Button BPM Electronics: RFFE Beam Test Results (FLASH, SwissFEL Test Inj.) Cold button (Ø=78mm) RMS position noise (single bunch): ~ 30 20pC ~ pC Warm button (Ø=40.5mm) RMS position noise (single bunch): ~ 20pC ~ 60pC Expect ~ 3 μm at pc, to be measured Warm button, 1 bunch Charge noise <0.05% at pc Average over 40 bunches

11 European XFEL Undulator Cavity BPM Electronics: Design Gain adjustment: 63dB range, 0.5dB steps RFFE MBU Crate: removable fan tray, redundant main power supply,... Differential ADC Inputs (cables removed) DOOCS & Timing Interface (SFP/Optical) I/Q downconversion to baseband. Active temperature stabilization (several sensors + heaters). Works with or without external trigger & ref. clock.

12 European XFEL Undulator Cavity BPM Electronics: Results SwissFEL Test Injector BPM Test Set-Up SwissFEL Test Injector BPM Test Set-Up Sampled RFFE IQ Signals Only top sample used (so far...) Determination of Position Resolution from Correlation of 3 EXFEL Undulator Cavity BPMs Histogram (X1+X3)/2 X2 See IBIC 12, TUPA27, M. Stadler et al.

13 European XFEL Undulator Cavity BPM Electronics: Results Position Resolution (rms noise, single bunch) Undulator cavity (Ø = 10 mm): ~ 11 2 pc (± 5 mm range) < pc (± 1 mm range) Transfer line cavity (Ø = 40.5 mm): ~ pc (± 1 mm range) 2x improvement feasible by digital removal of angle signal (15x bigger than for undulator BPMs) work in progress mm offset at 1 nc: 50 V signal! RFFE may need input protection via attenuator (4x worse low-charge resolution), or extra protection circuit (to be developed for IBFB) Charge Measurement rms Noise (single bunch) Undulator cavity (Ø = 10 mm): < pc < pc < 10 2 pc

14 SwissFEL Cavity BPMs: Improvements and Adaptations SwissFEL BPMs require similar position resolution at much lower charges improve sensitivity and production costs of cavity BPM design keep electronics similar to European XFEL design position resonator (used signal ~ position*charge) resonator gap width waveguide depth reference resonator (used signal ~ charge) Waveguides connected to beam pipe

15 SwissFEL Cavity BPMs: Improvements and Adaptations Injector and Linac Undulator (Baseline) Undulator (Alternative Option) Pickup Type Cavity (2 Resonators, Mode-Suppressing Couplers) Frequency GHz 4.8 GHz Loaded Q ~ 40 ~ 200 ~ Material Stainless Steel Cu-Coated Steel Gap Width 7 mm 7 mm TBD Waveguide Depth 14 mm 25 mm TBD Beampipe Ø 16 mm 8 mm 8 mm Signal [V/mm/nC] *** TBD RFFE IQ Downconversion* IF Frequency ~ 0 Hz ~ 50 MHz ADC 16-Bit 160MSPS (Linac/Injector: 12-Bit 500MSPS Option)** * Undulators (alternative option): single-channel downconversion feasible, to be evaluated ** Sample rates of available ADCs for European XFEL (E-XFEL) BPM electronics built by PSI *** E-XFEL Undulator: 2.9 V/mm/nC (Q=70) -> ~3x better low charge resolution for SwissFEL

16 SwissFEL Cavity BPMs: First Prototype Test Results SwissFEL Cavity-BPM 16 mm Prototype: Raw Signals SwissFEL BPM-16 Position Resolution Measurement Correlation Measurement < 0.8 μm RMS noise at 135pC and 0.35 mm offset (range > ±1mm) SwissFEL BPM Prototype: RFFE Output Signals SwissFEL BPM-16 Charge Resolution Measurement Low bunch-tobunch crosstalk IQ outputs, just Q shown Correlation with E-XFEL undulator BPM: < 0.1 pc RMS charge noise at 135pC bunch charge

17 1 Swiss Light Source: BPM System (and FOFB) Upgrade Present System Beam Dynamics Server PC Control Room GUI PCs 1+ blue=new hardware 1 Future System Beam Dynamics Server PC Control Room GUI PCs 1+ pink=new software/ firmware Part of BPM (Calc: X,Y,...) EPICS IOCs / VME Crates 12 Just for FOFB Algorithm EPICS IOCs / VME Crates DSP Boards Digitizer/DDC Boards RF Front- Ends BPM electronics Power Supply Interface Board Corrector Power Supplies 12H 12V 74H 74V FOFB electronics DSP Board Digitizer/DDC Boards RF Front- Ends BPM electronics Power Supply Interface Board Corrector Power Supplies 12H 12V 74H 74V FOFB electronics Stupid : Sends 4 amplitudes Intelligent/autonomous (X,Y, FFT, Fault Detect, FOFB Interface,...) 74 Button Pickups Corrector Magnets 74H 74V 74 Button Pickups Corrector Magnets 74H 74V beam beam

18 1 Beam Position Monitor Developments at PSI Swiss Light Source: BPM System (and FOFB) Upgrade Part of BPM (Calc: X,Y,...) Present System Beam Dynamics Server PC EPICS IOCs / VME Crates Control Room GUI PCs Slow GLOBAL feedback loop, few Hz: (RF frequency & horizontal dispersion correction) blue=new hardware 1 Just for FOFB Algorithm Future System Beam Dynamics Server PC EPICS IOCs / VME Crates Control Room GUI PCs pink=new software/ firmware Fast GLOBAL feedback loop (10-20kHz): New global real-time network DSP Boards Digitizer/DDC Boards RF Front- Ends Button Pickups BPM electronics Stupid : Sends 4 amplitudes Power Supply Interface Board Corrector Power Supplies Corrector Magnets 12H 12V 74H 74V 74H 74V FOFB electronics Fast LOCAL feedback loop (4kHz): Each DSP gets only data from 18 BPMs DSP Board Digitizer/DDC Boards RF Front- Ends Button Pickups BPM electronics Power Supply Interface Board Corrector Power Supplies Corrector Magnets 12H 12V 74H 74V Intelligent/autonomous (X,Y, FFT, Fault Detect, FOFB Interface,...) 74H 74V FOFB electronics beam beam

19 Swiss Light Source BPM System: EPICS GUI for DDC Filters Matlab/EPICS GUI allows real-time optimization of BPM filters (-> optimize for best orbit stability & lowest noise & latency...). Not available for commercial BPMs (have fixed black-box filters).

20 Swiss Light Source BPM System: First Prototype Test Results 1st prototype for new SLS BPM electronics: Just re-combining existing FEL BPM electronics modules (designed by PSI). Result: Position resolution 80nm RMS (2kHz BW)! But: SLS needs new dedicated RFFE (higher gain range, active temperature stabilization,...)

21 Summary and Outlook Modular approach for BPM system developments allows the use of similar electronics, firmware & software (!) for European XFEL, SwissFEL and Swiss Light Source Performance of prototype systems are promising European XFEL: < 5 m (warm buttons), < 0.5 m (undulator cavities) SwissFEL: < 1 m (@ 135 pc, ± 1 mm range), < 2 m (@ 10 pc) Swiss Light Source: < 100 nm (rms noise at 2 khz BW) Implementation of Systems between 2014 and 2018 Re-Use of electronics platform (digital back end) for other diagnostics