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

Wir schaffen Wissen – heute für morgen

Paul Scherrer Institut

Beam Position Monitor Developments at PSI

V. Schlott for the PSI Diagnostics Section

ESLS 2013, November 21st and 22nd 2013Volker Schlott,Volker Schlott,


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

Volker Schlott,Volker Schlott,

AcknowledgementsThe presentation summarizes the work from…:

Boris KeilRaphael Baldinger Goran MarinkovicCarl Beard Markus RoggliRobin Ditter Martin RohrerReinhold Kramert Markus StadlerWaldemar Koprek Daniel Treyer

Many thanks also for the support from our colleagues at…: DESY andCEA / Saclay / Irfu

European XFEL in-kind contributions are funded by…: Swiss State Secretary for Education, Research and Innovation (SERI)

ESLS 2013, November 21st and 22nd 2013



Motivation: Large Scale Projects• Swiss IK contribution to European XFEL (~ 470 systems from 2009 – 2015):

→ 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 (~ 150 – 250 systems from 2012 – 2017…):→ 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 2014 – 2016 (2018)):→ renewal & upgrade of BPM electronics (improved resolution at higher BW)→ fast orbit feedback with higher correction bandwidth (> 200 Hz)




Main Specifications for European XFEL BPMs• European XFEL (standard warm button BPMs for 0.1 – 1 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): 15 - 20 m / 25- 30 m

• European XFEL (undulator cavity BPMs for 0.1 – 1 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 0.1 – 1 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 train @ 10 Hz rep. rateESLS 2013, November 21st and 22nd 2013



Main Specifications for SwissFEL and SLS BPMs• SwissFEL (standard / transfer line cavity BPMs for 10 – 200 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 10 – 200 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 bunches) @ 100 Hz rep. rate

• Swiss Light Source (storage ring (FOFB) BPMs for 400 mA beam current (top-up)):→ position resolution: < 100 nm (rms) @ 2 kHz BW / m level for turn-by-turn→ aperture size: 65 mm (h) x 35 mm (v)→ drift (weeks): sub-m




Modular BPM / Diagnostics Platform Architecture


E-XFEL / SwissFEL Cavity BPM Electronics (Simplified)

ControlSystem

3-5GHz

RF Front-end MezzanineCarrierboard

Common housing, fan, power supply

LO

ADC0.1-0.5Gsps

FPGAVirtex-5

FXT

IQ

New SLS BPM Electronics (Simplified)

ADC0.1-5Gsps

FPGAVirtex-5

FXT500MHz Control

System

RF Front-end MezzanineCarrierboard

Common housing, fan, power supply



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)





Pickup Signal Stretched by Chirp Filter

RFFE output signal, mode2: S&H discharge

by external trigger

(=standard mode)

RFFE output signal, mode1: Automatic S&H discharge by

resistor (=non-standard mode

e.g. when external trigger

is missing)





Beam Test Results (FLASH, SwissFEL Test Inj.)Cold button (Ø=78mm) RMS position noise (single bunch):

~ 30 μm @ 20pC~ 5 μm @ 100-1000pC

Warm button (Ø=40.5mm) RMS position noise (single bunch):~ 11μm @ 20pC~ 5μm @ 60pC

Warm button,1 bunch

Expect ~ 3 μm at 150 – 1000 pC, to be measured

Charge noise <0.05% at 50 -

1000 pC

Average over 40 bunches



European XFEL Undulator Cavity BPM Electronics: Design


Gain adjustment: 63dB range, 0.5dB steps

• I/Q downconversion to baseband.• Active temperature stabilization (several sensors + heaters).• Works with or without external trigger & ref. clock.

Differential ADC Inputs

(cables removed)

DOOCS & Timing Interface

(SFP/Optical)

RFFE

MBU Crate: removable fan tray, redundant main power

supply, ...



European XFEL Undulator Cavity BPM Electronics: Results


See IBIC’12, TUPA27, M. Stadler et al.

Only top sample used (so far ...)

Histogram (X1+X3)/2 – X2

Sampled RFFE IQ Signals

SwissFEL Test Injector BPM Test Set-Up SwissFEL Test Injector BPM Test Set-Up

Determination of Position Resolution from Correlation of 3 EXFEL Undulator Cavity BPMs



European XFEL Undulator Cavity BPM Electronics: Results


Position Resolution (rms noise, single bunch)Undulator cavity (Ø = 10 mm):

~ 11 μm @ 2 pC (± 5 mm range)< 0.5 μm @ 100 – 1000 pC (± 1 mm range)

Transfer line cavity (Ø = 40.5 mm):~ 1 μm @ 100 – 1000 pC (± 1 mm range)

Charge Measurement rms Noise (single bunch)Undulator cavity (Ø = 10 mm):

< 0.06 % @ 100 – 1000 pC< 60 fC @ 100 pC< 10 fC @ 2 pC

2x improvement feasible by digital removal of angle signal

(15x bigger than for undulator BPMs) – work in progress ...

20 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)



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)

reference resonator (used signal ~ charge)

resonator gap width

“waveguide depth”

Waveguides connected to beam pipe



SwissFEL Cavity BPMs: Improvements and Adaptations


Injector andLinac

Undulator (Baseline)

Undulator (Alternative Option)

Pickup Type Cavity (2 Resonators, Mode-Suppressing Couplers)Frequency 3.284 GHz 4.8 GHzLoaded Q ~ 40 ~ 200 ~ 100 - 1000Material Stainless Steel Cu-Coated SteelGap Width 7 mm 7 mm TBDWaveguide Depth 14 mm 25 mm TBD

Beampipe Ø 16 mm 8 mm 8 mm

Signal [V/mm/nC] 7.1 9.3*** TBDRFFE IQ Downconversion*

IF Frequency ~ 0 Hz ~ 50 MHzADC 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



SwissFEL Cavity BPMs: First Prototype Test Results



IQ outputs, just Q shown

Low bunch-to-bunch crosstalk

SwissFEL BPM Prototype: RFFE Output Signals

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)

Correlation with E-XFEL undulator BPM:

< 0.1 pC RMS charge noise at 135pC bunch charge

SwissFEL BPM-16 Charge Resolution Measurement


Swiss Light Source: BPM System (and FOFB) Upgrade



beam

RF Front-Ends

Digitizer/DDCBoards

DSP Boards

Beam Dynamics Server PC

Button Pickups

CorrectorMagnets

12

74

74

74 74H74V

CorrectorPower

Supplies

74H74V

Power SupplyInterface

Board12H12V

EPICS IOCs / VME Crates 12

1 Control RoomGUI PCs

BPM

electronics

FOFB

electronics

1+

“Stupid”: Sends 4 amplitudes

Part of BPM (Calc: X,Y,...)

Present System

beam

RF Front-Ends

Digitizer/DDCBoards

DSP Board


Button Pickups

CorrectorMagnets

1

37

74

74 74H74V

CorrectorPower

Supplies

74H74V


Board12H12V



BPM

electronics

FOFB

electronics

1+

Intelligent/autonomous (X,Y, FFT, Fault Detect, FOFB Interface, ...)

Just for FOFB

Algorithm

Future Systemblue=newhardware

pink=newsoftware/firmware


Swiss Light Source: BPM System (and FOFB) Upgrade



beam

RF Front-Ends

Digitizer/DDCBoards

DSP Boards


Button Pickups

CorrectorMagnets

12

74

74

74 74H74V

CorrectorPower

Supplies

74H74V


Board12H12V



BPM

electronics

FOFB

electronics

1+

“Stupid”: Sends 4 amplitudes

Part of BPM (Calc: X,Y,...)

beam

RF Front-Ends

Digitizer/DDCBoards

DSP Board


Button Pickups

CorrectorMagnets

1

37

74

74 74H74V

CorrectorPower

Supplies

74H74V


Board12H12V



BPM

electronics

FOFB

electronics

1+

Intelligent/autonomous (X,Y, FFT, Fault Detect, FOFB Interface, ...)

Just for FOFB

Algorithm

blue=newhardware

pink=newsoftware/firmware

Present System Future System

Fast LOCAL feedback loop (4kHz): Each

DSP gets only data from 18

BPMs.

Slow GLOBALfeedback loop,

few Hz: (RF frequency & horizontal dispersion correction)

Fast GLOBALfeedback loop

(10-20kHz): New global real-time

network.


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).


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, ...)


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

Documents

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