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UK LC accelerator programme

UK LC accelerator programme. Philip Burrows John Adams Institute Oxford University. CLIC-UK (started March 2011). CI/Manchester: main beam RF, crab cavities CI/Lancaster: crab cavities ASTeC: drive-beam quads + crab cavities JAI/Oxford: beam FB+FF, laserwire, BPMs

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UK LC accelerator programme

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  1. UK LC accelerator programme Philip Burrows John Adams Institute Oxford University

  2. CLIC-UK (started March 2011) CI/Manchester: main beam RF, crab cavities CI/Lancaster: crab cavities ASTeC: drive-beam quads + crab cavities JAI/Oxford: beam FB+FF, laserwire, BPMs JAI/RHUL: transverse beam size, cavity BPMs Dundee: longitudinal beam profile monitor

  3. Drive beam

  4. Drive Beam Quadrupoles (ASTeC) Erik Adli & Daniel Siemaszko Low Energy Quad High Energy Quad High energy quad – Gradient very high Low energy quad – Very large dynamic range

  5. Basic Engineering Concept Steel PM Block Steel Pole Non-magnetic support Norbert Collomb

  6. Measured Field Quality

  7. Drive beam phase feed-forward (Oxford) Schulte

  8. Drive beam phase feed-forward Skowronski

  9. CTF3 phase FF prototype

  10. Phase monitor (Frascati) Signal down-mixer (CERN) Feedback processor + firmware (JAI Oxford) Drive amplifier (JAI Oxford) Kickers (Frascati)  1 mrad kick  1.2 mm path length change  17 degrees at 12 GHz  0.2 degree resolution CTF3 phase FF prototype

  11. 65kW peak power Bandwidth > 50 MHz 1.2 us (non-combined) beam pulse < 10% droop PCB-based design using SiC FETs Drive amplifier

  12. Feedback and instrumentation

  13. ATF2/KEK: prototype final focus • Goals: • 37 nm beam spot (65 nm achieved 2013) • Beam spot stabilisation at c. 5 nm level 14

  14. ATF2/KEK: prototype final focus Beam feedback + feed-forward systems Precision cavity + stripline BPMs Beam size diagnostics Beam tuning techniques 15

  15. Beam feedback + feed-forward (Oxford) • Aim to stabilise beam in IP region using 2-bunch spill: • 1. Upstream FB monitor beam at IP • 2. Feed-forward from upstream BPMs  IP kicker • 3. Local IP FB using IPBPM signal and IP kicker 16

  16. Upstream FONT5 System Analogue Front-end BPM processor FPGA-based digital processor Kicker drive amplifier Beam Strip-line kicker Stripline BPM with mover system

  17. Interaction Point FONT System Analogue Front-end BPM processor FPGA-based digital processor Kicker drive amplifier Beam • Designed in house • 12.5 cm stripline kicker • Based on ATF stripline BPMs Strip-line kicker Cavity BPM

  18. ATF2 beam stabilisation results • Upstream FB: beam stabilised at IP to • ~ 300 nm • 2. Feed-forward: beam stabilised at IP to • ~ 106 nm • 3. IP FB: beam stabilised at IP to ~ 93 nm • Getting interesting! (i.e. hard)

  19. IP Feedback in CLIC CDR

  20. ATF2 beam position monitors (RHUL) IBIC : Beam Instrumentation at ATF2 (S. T. Boogert for ATF collab.)

  21. CLIC Main beam BPM prototype • Low-Q stainless steel cavity • Simulation in • Gdfidl • Microwave studio • Measurement • VNA @ RHUL (before) and CERN (after brazing) • Beam measurements @ CALIFES • Dipole cavity • fdipole=14.993 GHz • QL= 274 • Q0=450 • Reference cavity • fdipole=14.960 GHz • QL= 150 IBIC : Beam Instrumentation at ATF2 (S. T. Boogert for ATF collab.)

  22. Transverse beam size (JAI)

  23. Electro-Optical Spectral Decoding (Dundee) Simulations of bunch-induced polarisation change and non-linear interaction Spectral Decoding (EOSD): The Coulomb field temporal profile of the e-bunch is encoded on to a time-wavelength correlated optical probe pulse. The profile is read-out through the spectrum of the probe pulse. Where, Where,

  24. Implementation of the EO monitor at CALIFES Diagnostic section Accelerating structure Photo-injector Beam direction Grating P: Polarizer H: Half wave plate Q: Quarter wave plate : Mirror with actuators : Finger camera Laser: Wavelength: 780 nm Duration: 100 fs Repetition: 37.4815 MHz Pulse energy: 2.7 nJ Crystal: Thickness: 1mm Separation: 5-10 mm In Lab In CLEX 10 Plane mirrors 3 Gratings 3 Lenses 1 Fibre head 1 Laser 1 ICCD Camera 1 Motor stage 7 Plane mirrors 2 Polarizers 2 Wave plates 1 Lens 1 Fibre head • 10 Actuators • 3 Rotation motors • Finger cameras

  25. Crab cavity (Lancaster, ASTeC)

  26. Full structure(with couplingand damping) magEz at 11.9942 GHz

  27. CLIC Prototype 1 - UK manufactured The 1st CLIC crab cavity prototype has been manufactured by Shakespeare Engineering in the UK. Tolerance and surface roughness on single parts have been measured and are acceptable. • Test by measuring S-parameters at each port then combining to get the dual port F-parameters. • Cavities have not been tuned yet. Structure is planned to be tested at SLAC in the near future.

  28. Revised Crab Synchronisation Scheme RF path length is continuously measured and adjusted 4kW5ms pulsed 11.8 GHz Klystron repetition 5kHz Cavity coupler 0dB or -40dB Cavity coupler 0dB or -40dB Waveguide path length phase and amplitude measurement and control Forward power main pulse 12 MW Single moded copper plated Invar waveguide losses over 35m ~ 3dB -30 dB coupler -30 dB coupler Expansion joint Expansion joint LLRF Magic Tee LLRF Reflected power main pulse ~ 600 W Reflected power main pulse ~ 500 W Phase shifter trombone Phase shifter trombone (High power joint has been tested at SLAC) Waveguide from high power Klystron to magic tee can be over moded Phase Shifter Main beam outward pick up Main beam outward pick up From oscillator 48MW200ns pulsed 11.994 GHz Klystron repetition 50Hz Vector modulation 12 GHz Oscillator Control

  29. Board Development and CW tests Front end electronics to enable phase to be measure during the short pulses to an accuracy of 2 milli-degrees has been prototyped and dedicated boards are being developed. MCU PLL controller 10.7 GHz VCO Wilkinson splitter Digital phase detector 400 ns span: RMS: 1.8 mdeg Pk-Pk: 8.5 mdeg DBMs 90 s span: Drift rate : 8.7 mdeg/10s Total drift: 80 mdeg Power Meters Inputs

  30. Main linac structure studies (Manchester) Alternative designs including wakefield suppression of HOMs

  31. CLIC_DDS_E Elliptical Design –E Fields b a Circular Square Single undamped cell Iris radius=4.0 mm Convex ellipticity

  32. UK LC machine expertise • Beam dynamics, beam transport, backgrounds …

  33. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs …

  34. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs … • Feedback and controls: fast analogue + digital FB …

  35. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs … • Feedback and controls: fast analogue + digital FB … • Alignment, position monitoring and stabilisation …

  36. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs … • Feedback and controls: fast analogue + digital FB … • Alignment, position monitoring and stabilisation … • Undulators, targets, beam dumps …

  37. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs … • Feedback and controls: fast analogue + digital FB … • Alignment, position monitoring and stabilisation … • Undulators, targets, beam dumps … • RF cavities: wakefields, higher-order modes …

  38. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs … • Feedback and controls: fast analogue + digital FB … • Alignment, position monitoring and stabilisation … • Undulators, targets, beam dumps … • RF cavities: wakefields, higher-order modes … • Collimation systems: design, sim. + meas. of wakefields

  39. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs … • Feedback and controls: fast analogue + digital FB … • Alignment, position monitoring and stabilisation … • Undulators, targets, beam dumps … • RF cavities: wakefields, higher-order modes … • Collimation systems: design, sim. + meas. of wakefields • Vacuum systems

  40. UK LC machine expertise • Beam dynamics, beam transport, backgrounds … • Beam instrumentation: • transverse and longitudinal emittance, BPMs … • Feedback and controls: fast analogue + digital FB … • Alignment, position monitoring and stabilisation … • Undulators, targets, beam dumps … • RF cavities: wakefields, higher-order modes … • Collimation systems: design, sim. + meas. of wakefields • Vacuum systems • Magnet systems …

  41. Applicable to • Beam delivery system • Machine – detector interface • Damping rings • Positron source •  Strong role in a European team to deliver key system(s) for ILC

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