Overview on Beam Instrumentation Cyrille Thomas On behalf

Overview on Beam Instrumentation Cyrille Thomas On behalf of the Beam Diagnostics Section www. europeanspallationsource. se

ESS Linac Diagnostics layout 2. 4 m LEBT Source 75 ke. V 4. 6 m RFQ 352. 21 MHz 3. 8 m 39 m MEBT DTL 3. 6 Me. V Warm linac 704. 42 MHz 56 m 77 m Spokes Medium β 90 Me. V 216 Me. V 179 m High β 571 Me. V Cold linac Warm Linac Cold Linac HEBT & Contingency 2000 Me. V HEBT / A 2 T Target HEBT and A 2 T Instrument Function Target BCM (current) Protection 9 4 5 BLM (loss) Protection 15 52 190 BPM (phase and position) Monitoring / Protection 2+25 43 29 - 3 EMU (emittance) Scanning 2 - - WS/NPM (transverse profiles) Scanning/ Monitoring 3/2 5/5 3/2 - - BSM (long. Profile) Scanning 2 - - Imaging (2 D profile) Monitoring / Protection 2 1 Grid (1 D profile) Monitoring / Protection - - - 1 - APTM (current out) Protection - - - 3 21 - Dump. L 2 6

Beam modes: Commissioning and Operation 5 μs 100 μs 6 - 62. 5 m. A Commissioning 6 -62. 5 m. A Commissioning ≦ 14 Hz ≦ 1 Hz 2. 86 ms 6 -62. 5 m. A Commissioning ≦ 0. 034 Hz • • Operation 14 Hz Main goal: achieve 2. 86 ms pulse on target to the Neutron Instruments Peak Current as adjustment variable • For tuning RF (minimize beam loading) • For Production (control power while meeting neutron instruments 2. 86 ms pulse requirements)

Measurements provided by beam diagnostic systems Measurement Emittance (4 -D) Current Detect Beam loss Current Out of Aperture Instrument Type observation Comment EMU scanning Measurement of single mode point, holds the machine while been used Publishes emittance value in 1 axis once scan achieved and after processing the data (minutes to hours) BCM Monitoring MPS interlock Running IOC at any time MPS interlock Publishes peak current values at 14 Hz. Waveform available BLM Monitoring MPS interlock Running IOC at any time MPS interlock Publishes loss detected and needs calibration to determine MPS threshold APTM Monitoring MPS interlock Located at the Dump. L, NSW and Target Monolith MPS interlock Publishes current distribution measured outside define aperture at time scale from 1µs to minutes 4

Measurements provided by beam diagnostic systems Measurement Instrument WS Transverse Beam Profile NPM GRID Type observation Comment Scanning Limited to low energy Beam Mode (pulse length <50µs) Publishes 1 D transverse profile and beam size, once scan achieved. Sampling waveforms could be processed to produce beam profile along pulse. Detection threshold at the limit of the WS, no other limitation Publishes 2 x 1 D transverse profiles and beam size per pulse (14 Hz). Fast-Kinetic mode can be developed to acquire (100) profiles per pulse. Monitoring In Target Monolith Publishes 2 x 1 D profiles at 14 Hz, with similar profile analysis as for the imaging. Redundant measurement to imaging. MPS interlock. Located at the Dump. L and Target Monolith Monitoring 2 D current density distribution Imaging Monitoring Long. Beam profile BSM scanning Measure averaged bunch profile Limited to specific beam modes Publishes 2 D beam profile at 14 Hz, with image analysis such as beam size, position, current density homogeneity, beam current density out of nominal 99% power area. MPS interlock (planned but not demonstrated). Publishes waveform of bunch profile, with additional measurement of the bunch length 5

Interface Definition: beam instrumentation and beam physics apps • All beam instrumentation devices are integrated into EPICS IOCs • Channel Access used in prototypes; will follow ICS standards and work with them to deploy devices: intend to use PV Access for first beam in Lund. • Beam physics apps will access some device IOCs directly; where appropriate, an intermediate layer will be provided by beam diagnostics and ICS: • • Beam Diagnostics Section primarily develops functionality that requires instrumentation expertise • • Combine correlated data from multiple instrumentation devices and types Proxy to control load on individual IOCs Communication via PV Access goal is to increase robustness of the measurement data provided to the high level applications; the beam physics section develops the accelerator model-based applications Beam Diagnostics Section will also benefit from high level apps • • Device commissioning and performance verification (System Acceptance Tests) Calibration and studies (ex. Difference orbits to verify BPMs, Raster scanning for imaging calibration, etc) 6

Example of diagnostics • EMU: Emittance – Delivered and operational • BPM: phase and position – Prototype well advanced – EPICS IOC in development, nearly achieved 7

Example of scanning instrument Emittance: invasive measurement, single use Scanning diagnostic, as BSM, WS Courtesy B. Cheymol 8

Time resolved at 1 MHz X’ (160 mrad) Log scale Signal for a single point in phase-space X (100 mm) Beamlet angular profile Scan position and Angles: waveform data for all phase-space points Ø Large data set to store and analyse Ø Calculation of the emittance Main beam Extra beam under investigation 11/01/2017 Courtesy B. Cheymol -40 Secondary electrons generated on repeller/second slit 0 q (mrad) Scattered protons on deflecting plates 40 9

• Example of monitoring instrument BPM: Monitoring diagnostic for the beam phase and position • • • Non-invasive Multiple users Other examples: BCM, BLM, NPM, target instrumentation, etc. High level Application access: - RAW data, sampled at ~88 MHz - Amplitude and phase of the signal on each antenna - Phase relative to the Phase Reference Line - Beam Position calculation (D / S) - SUM of the amplitudes (proxy of current x bunch length) From Fredrik K. presentation, BPM PDR, October, 2017 10

BPM processing Beam Position BPM RAW data Baseband phase/amplitude Courtesy of Rafael Baron Baseband filtered phase/amplitude Beam Phase relative to PRL 11

BPM: EPICS IOC overview Example: BPM • Near IQ sampling algorithm for position, magnitude and phase calculation • Using machine timing system for triggers and clocks • Operating in pulsed mode • Digitizing at 88. 025 Mhz • Configurable pulse duration to work with different machine modes • MPS interface (real-time) and alarm reporting (software) • IOC can handle up to 20 BPM stations • 2 BPMs per AMC (granularity of firmware and software) • 4 input signals per BPM + reference (shared among two BPMs) • data time stamping per pulse for correlation Courtesy of Hinko Kocevar 12

Phase, Amplitude, Position is available as Channel Access PV, published at 14 Hz Ø Application using these PVs should be accessing a Service Layer or could eventually directly through CA 13 Courtesy of Hinko Kocevar

EPICS IOC high level PVs • 18 waveforms per BPM: – X & Y position waveforms (2) – Antenna magnitudes & phase waveforms (8) – Magnitude & phase sum waveforms (8) • • • Filtering Region of interest (flat top) Statistics, averaging, FFT, etc. File saving (HDF 5) of bulk data (what does not go to archiver) Data-of-demand functionality • On event, update PVs with measurements buffered prior to event and pulses occurring after event • use cases: post mortem after MPS trip, detect near missed events 14 Courtesy of Hinko Kocevar

Service layer • Combine correlated data from multiple instrumentation devices and types • Proxy to control load on individual IOCs • Provide results as PVs so that all generic EPICS tools are supported • Beam diagnostics section primarily develops functionality that requires instrumentation expertise; goal is to increase robustness of the measurement data provided to the high level applications; the beam physics section develops the accelerator model-based applications • Will consider EPICS V 4 features in the future; V 3 for now, with all of the attendant simplicity and limitations. o It as a set of tools to: o o o • allow scripting against BI devices (for data correlation) • proxy the individual IOC data (to be served to multiple EPICS clients) • archive the IOC data for off line processing • calibrate the individual BPM BI group prepared to investigate, develop and support service layer tools that would be of interest to BP BP develop XAL applications and then port (with BI) to ICS service layer tools Currently finalizing EPICS IOC and debugging outstanding issues 15 Courtesy of Hinko Kocevar

Thank you 16