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WP5.3 Collimation

WP5.3 Collimation. Nigel Watson (Birmingham) LC-ABD Review, Oxford 24 th October 2005. Overview of WP5.3 goals Status of work to date Plans for the future. People. UK project integrated with EUROTeV “Spoiler Wakefield and Mechanical Design” task

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WP5.3 Collimation

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  1. WP5.3 Collimation Nigel Watson (Birmingham) LC-ABD Review, Oxford 24th October 2005 • Overview of WP5.3 goals • Status of work to date • Plans for the future

  2. People • UK project integrated with EUROTeV “Spoiler Wakefield and Mechanical Design” task • Project web: http://hepunx.rl.ac.uk/swmd/ • Birmingham: N.Watson • CCLRC: C.Beard,G.Ellwood,J.Greenhalgh,J.O'Dell,L.Fernandez • CERN: F.Zimmermann,D.Schulte [EUROTeV] • DESY: I.Zagorodnov [EUROTeV] • Lancaster: D.Burton,N.Shales,J.Smith,A.Sopczak,R.Tucker • Manchester: R.Barlow,A.Bungau,G.Kurevlev,A.Mercer – also WP1.2 • TEMF, Darmstadt: M.Kärkkäinen,W.Müller,T.Weiland [EUROTeV] • For ESA tests, working closely with • WP1.1on optics for wakefield and beam damage studies • SLAC for all aspects Nigel Watson/Birmingham

  3. WP5.3 Goals Design / optimisation of spoiler jaws (geometry and materials) for wakefield and beam damage performance • Development of improved EM modelling methods • Benchmarking of wakefield calculations against experiments • SLAC ESA beam test / data analysis • RF bench tests (training/code comparisons) • Tracking simulations with best models of wakefields • Simulations of beam damage to spoilers • Material studies using beam test Project web: http://hepunx.rl.ac.uk/swmd/ Ongoing: analytic calcs. ECHO-2D/3D Ongoing: Mafia, GdfidL Scheduled Jan. ‘06, Feb. ‘06 In preparation Ongoing, with WP1 Recently started Planning Nigel Watson/Birmingham

  4. Theoretical Studies • Fledgling activity in Lancaster (Tucker, Burton) • New spacetime covariant field-theoretic description of electron beam dynamics is under development • Includes a covariant perturbation expansion of the electric current about the forward light cone • Exact solutions and their relation to solutions obtained using the perturbation scheme are under scrutiny • Will be used to analyse dynamics of an electron beam in collimator geometries • Predications to be compared with results from conventional EM modelling packages Nigel Watson/Birmingham

  5. Computer Simulations of Spoiler designs [Carl Beard] • Codes being developed/used to measure the impedance of vessels • ECHO2D, MWStudio, HFSS, GDFIDL, MAFIA, etc etc • Calculation errors due to small angle of taper • Off axis measurements 1mm ECHO 2D/3D [TEMF] 1m The length of the structure and the frequency make simulation time very long user defined pulse possible

  6. Wakefield Modelling • Increased emphasis on simulations • Development of ECHO-3D [TEMF, Darmstadt] • Baseline simulations with MAFIA (Beard), compared with GdfidL (J.Smith) • RF bench tests (ASTeC, Lanc.), not directly applicable for ILC bunch length • Training and code benchmarking • New RA (EUROTeV) at ASTeC starts 31 Oct., effort on data analysis, ESA tests, collimator damage Collab. with A.Liapine for GdfidL (WP4.2) GdfidL MAFIA Sensitive to mesh definitions Long. wake (V/pC) [Contacts with Bruns, Ng, Corlett] S (m) Nigel Watson/Birmingham

  7. Collimator Wakefield Beam Test • Wakefield beam tests at ESA • SLAC Proposal T-480 (Tenenbaum, Watson et al), 4/2005 Many people involved directly, see proposal • Part of evolving programme of ILC tests at ESA • Purpose • Commision/validate CollWake Expt. at ESA • Additional study of resistive wakes in Cu • First study of 2-step tapers • Development of ECHO-3D code (TEMF) for shallow tapers/short bunches • Schedule • Short run, 4-8 Jan. 2006, 4 collimators • Longer run, 20 Feb. – 1 Mar. 2006, 8 collimators • Status • Beamline prep., DAQ, BPM set up ongoing • 4 sets of collimators designed and fabricated in house at RAL (O’Dell, Greenhalgh), 5 sets ready to ship Nov. 3. • Related activity • Implementation of validated/realistic 3D wakefunctions in Merlin • Collimator damage studies also envisaged at ESA Nigel Watson/Birmingham

  8. ESA beamline layout Wakefield box • Measure kick factor using incoming/outgoing beam trajectory, scanning collimator gap through beam • Stage 1, 5 rf cavity BPMs, 1 stripline BPM, 2 wire scanners • Wakefield box, proposal for 2 sets of four pairs of spoiler jaws • Each set mounted in separate “sandwich” to swap into WF box • (relatively) rapid change over, in situ • 4 day run, Jan 4-8, 2006 • 9 day run, Feb 20 – Mar 1, 2006 Nigel Watson/Birmingham

  9. Optical design • Optical design of A-line for WF expt., WP1.1 (F.Jackson/D.Angal-Kalinin) sy~100mm and flat in vicinity of WF box Nigel Watson/Birmingham

  10. Wakefield box 1500mm ESA sz ~ 300mm – ILC nominal sy ~ 100mm (Frank/Deepa design) Magnet mover, y range = 1.4mm, precision = 1mm Nigel Watson/Birmingham

  11. 38 mm h=38 mm L=1000 mm a r=1/2 gap As per last set in Sector 2, commissioning Extend last set, smaller r, resistive WF in Cu 7mm cf. same r, tapered Nigel Watson/Birmingham

  12. RF Bench Tests ~1.7m • From SRS tests (sz~6mm) • Consider vertical plane operation to avoid sag • Critical issue: • Pulse speed • Time ~ LC bunch sz • ~1 ps • Survey, fastest available “off the shelf” pulse generator for TDR ~ 10ps (Tek. 80E04 module+PSPL module+ TDS8200 scope) • Use for training/benchmarking in general of codes [From Hill&Pugh, EPAC’94] Nigel Watson/Birmingham

  13. [Carl Beard] Impedance Rig

  14. Impedance Rig 2 Matching Parts Test Vessels Launch cone

  15. [Contact with F.Caspers] Decided bench tests less urgent/critical Will not use to design test beam proposal Useful for training/education Impedance Rig 3 Tektronics 7854 TDR Scope 6 GHz NA – S-parameter test set

  16. New results A. Mercer Vertical profile histograms with count vs displacement No wakefields Simulation Parameters20mrad opticsSR onCollimation onVertical plane consideredOffset at linac exit Wakefields present • Corresponds to :- 1.1% y growth for a one 1y offset - 9.4% y growth for a 3y offsetHigher modes decreasing importance Difficult to see but profile broadens as expected Collimation Summary Talk, Snowmass 2005, ILC WG4, Frank Jackson

  17. Damage Studies • Initial ANSYS studies to check steady state heating (Ellwood and Kurevlev) • Next steps, real energy deposition profile (EGS/Fluka) • Study transient effects, fracture, etc. • Will call on CCLRC expertise from NF target studies as necessary • Discussions with Lew Keller at DL Collim. Meeting, 2-3 Nov. • Beam tests to be designed following simulations • Could use ESA • Quantify damage • Consider using new collimators in these tests – assess impact on measured wakefields [G.Ellwood] Nigel Watson/Birmingham

  18. Future Plans • Further round of collimators for test at ESA, based on improved 3d calculations • Iterate on candidate designs studies in tracking simulations (WP1) • Continue study into beam damage/materials • Devise beam test if/as necessary • Combine information on geometry, material, construction, to find acceptable baseline design regarding all of • Wakefield optimisation • Collimation efficiency • Damage mitigation Nigel Watson/Birmingham

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