Feedback + feed-forward plans Philip Burrows John Adams Institute - PowerPoint PPT Presentation

Feedback + feed-forward plans Philip Burrows John Adams Institute Oxford University Philip Burrows UK-CLIC kickoff meeting, CERN 13/4/11 1

Outline • The UK team • Main-beam IP feedback • Drive-beam phase stability feed-forward • Summary Philip Burrows UK-CLIC kickoff meeting, CERN 13/4/11 2

Feedback On Nanosecond Timescales Beam-based FB/FF R&D for future Linear Colliders Philip Burrows Glenn Christian Javier Resta Lopez Colin Perry Graduate students: Ben Constance Robert Apsimon Douglas Bett Alexander Gerbershagen Michael Davis Neven Blaskovic Valencia, CERN, DESY, KEK, SLAC Philip Burrows UK-CLIC kickoff meeting, CERN 13/4/11 3

IP intra-train feedback system - concept Last line of defence against relative beam misalignment Measure vertical position of outgoing beam and hence beam-beam kick angle Use fast amplifier and kicker to correct vertical position of beam incoming to IR FONT – Feedback On Nanosecond Timescales Philip Burrows UK-CLIC kickoff meeting, CERN 13/4/11 4

CLIC IP FB system • Prototype IP FB hardware has been developed since 2000 Philip Burrows ALCPG11, Eugene 21/03/11 5

FONT2 results – NLCTA (2001) Beam starting positions beam start beam end Beam flattener on Feedback on 4 1 2 3 Delay loop on

CLIC IP FB system • Prototype IP FB hardware has been developed since 2000 • CLIC IP FB luminosity simulations (EuroTeV, EUCARD) • For past 18 months have been working with MDI team (Lau Gatignon et al) on realisation of an IP intra-train FB system engineered for CLIC • Approved as baseline at CTC - February 2010 • Interactions on mechanical integration with Alain Herve et al February – June 2010 • Agreed on baseline conceptual engineering design – July 2010 • Documented in draft sections for CDR – October 2010 • Ready to provide any modifications to CDR text Philip Burrows ALCPG11, Eugene 21/03/11 7

CLIC Final Doublet region Elsner Philip Burrows ALCPG11, Eugene 21/03/11 8

Technical issues for TDR phase • Engineering of real hardware optimised for tight spatial environment: BPM, kicker, cables … • Large (and spatially-varying) B-field  operation of ferrite components in kicker amplifier?! • Further studies of radiation environment for FB system: was studied for ILC, so far preliminary for CLIC; where to put electronics? need to be rad hard? shielded? • EM interference: beam  FB electronics kicker  detector Philip Burrows ALCPG11, Eugene 21/03/11 9

Draft work programme • Simulation, design and prototyping of IP feedback system for luminosity stabilisation and optimisation • Integration of components within Machine Detector Interface (MDI) design • Completion of the ATF2 prototype systems as part of the ATF2 collaboration goals of 37nm beam size and nanometer-level beam stabilisation • Bench testing of relevant component prototypes, and exploration of the possibility of beam tests at CTF3 • Provision of feedback system parameters for modeling the integrated performance of feedback and feed-forward systems in the global CLIC design Philip Burrows ALCPG11, Eugene 21/03/11 10

FONT5 location

FONT5 layout P1 P2 P3 To dump K1 QD10X QF11X K2 QD12X QF13X QD14X QF15X FB board P2  K1 (‘position’) P3  K2 (‘angle’) DAQ P3  K1

FONT5 beamline hardware 3 new BPMs and 2 new kickers installed in new ATF2 extraction line February 2009; BPM movers installed 2010

Each FONT5 system loop 300ns train of bunches separated by 150ns Kicker BPM e- Drive Analogue BPM amplifier processor Digital feedback 14

FONT3 ‘CLIC’ prototype at KEK/ATF (2004-5) 56ns train of bunches separated by 2.8ns Kicker BPM BPM BPM 1 2 3 e- Analogue BPM processor FB loop closed with electronics latency 13ns

P2  K1 loop jitter reduction Bunch 1 Bunch 2 Bunch 3 13 um  5 um  3 um

P2  K1 loop jitter reduction Bunch 1 Bunch 2 2.1 um  0.4 um Factor of 5 jitter reduction

CLIC drive beam phase FF system • For past 20 months have been working with Daniel Schulte, Frank Stulle et al on concept for a drive-beam phase stability FF system • Meetings to map out requirements for amplifier system needed to provide phase correction – August 2009 – August 2010 • Preliminary design presented – October 2010 • Documented in draft sections for CDR – November 2010 • Ready to provide any modifications to CDR text 18

Reminder of phase feed-forward concept

Requirements & Assumptions - 1 Based on discussion in August 2009 , we assumed: Speed: 10ns - we shared the bandwidth limitation equally between kicker and amplifier - kicker active length is limited to 1.1m - split amplifier bandwidth equally between amplifier modules and combining system - each needs a 70MHz bandwidth Kickers: stripline kickers, 20mm clear aperture, 1m long - ~120 ohm impedance, balanced - each connected to amplifier with pair of coaxial cables - fit maximum possible total length of kickers for minimum total power required - this means 4 at each bend (3, slightly longer, might be better)

Requirements & Assumptions - 2 Deflection: +/-720 μ rad at each bend - divided over 4 kickers = +/-180 μ rad at each Amplifier architecture: modular, MOSFET - standard solution for fast, high-power amplifiers - output from many low power modules have to be combined - output voltage has to be stepped-up to provide the kV needed by the kicker - the very low duty factor required (0.002%) is very unusual - it allows extremely high power densities and (relatively) low cost - note: MOSFETs have almost entirely superceded bipolar transistors in this role

A Preliminary System Concept 1 dipole magnet 1m kicker 5m 8m 8m NOT TO 250kW amp SCALE - 4 kickers at each bend - 250kW peak power amplifier to each kicker - 256 amplifier modules in each amplifier - 1.2kW output each amplifier module (1kW after losses in combining etc)

A Preliminary System Concept 2 - amplifier size: 60 x 60 x 30cm (=100 litres) min (double that is more comfortable) - amplifier cost: £75K per 250kW amplifier (£300 per kW delivered to kicker) *** This is all very very approximate *** - it makes no allowance for technological progress - no single dominant cost, so estimates very rough until details worked out - very dependent on high-volume costs: we have no sound basis for these - 16 amplifiers & kickers / drive beam, 768 amplifiers total, 200MW total peak power - SYSTEM COST: £60M (perhaps +/-£30M)

Modified Design (Feb 2010) - required kick angle at each bend was reduced to +/-375 μ rad - this would have reduced power per kicker to 66kW peak - much more reasonable than the previous 250kW - but energy spread of beam & dispersion of chicane increased kicker aperture - 0.5% rms energy spread, 1m dispersion - adds 5mm rms spread to beam width in middle section - to accept up to 4 σ in energy, extra 40mm aperture needed - allowing for beam deflection and a finite beam size, need 50mm aperture - brings power back up to 410kW peak - allowing any sort of margin brings this to 600kW - eg for a slightly higher energy spread than assumed Later it was indicated that full kick would not be essential at full bandwidth - this may prove a useful dispensation

Amplifier Modules Module power is a matter of cost and size - sweet spot looks today to be 1 to 2kW peak for 100MHz module bandwidth - we are forced to low voltage, low impedance operation, and transforming the output  2kW peak output 10ns amplifier module  typical fast, high voltage MOSFETs (DE150-501N)

Engineering validation for CLIC amplifier output stage: - can we actually get the predicted performance? combining system: - can we do this reliably? - can we do it at the final power levels needed? - can we get adequate frequency response? transformers and associated ferrites: - will they work well enough? - what are the detailed properties of the ferrites? - how big and how expensive will they end up? size and cost: - push an amplifier module to a more-or-less finished design - that would set an upper bound on size and cost - amplifier module will dominate system cost system concepts: - functional test of a small-scale system would be an appropriate next stage - eg: 16 amplifier modules and one combining stage, driving a kicker

Timescale This is a serious project for 1 FTE fully-dedicated engineer! Basic feasibility study  conceptual design 2-3 years Build + test prototype unit 1-2 years 27