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SPOILER WAKEFIELDS and MECHANICAL DESIGN

SPOILER WAKEFIELDS and MECHANICAL DESIGN. Adriana Bungau The University of Manchester

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SPOILER WAKEFIELDS and MECHANICAL DESIGN

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  1. SPOILER WAKEFIELDS and MECHANICAL DESIGN Adriana Bungau The University of Manchester Manchester, 24/04/2006

  2. Outline • Motivation • Wakefield simulations 2.1 Progress for ESA tests - ESA experiment - Collimator fabrication 2.2 Wakefield studies - Gdfidl/Mafia - Merlin studies 3 Material damage - Geant4/Fluka studies - Ansys studies 4. Future plans

  3. spoiler Motivation Aim : optimal design of the ILC colimators to minimise wakefield effects • Transverse wakefields excited can lead to • emittance dilution • amplification of position jitter at the IP N.Watson 1% halo is enough to damage a thick collimator (L.Keller) • Damage near the edge is easier than in the middle of the solid volume Main goal: the collimators should be able to survive at 2 bunches at 250 GeV and 1 bunch at 500 GeV

  4. People • Birmingham: N.K.Watson (+D.Adey, M.Stockton) • CCLRC: C.Beard,G.Ellwood,J.Greenhalgh,J.O'Dell,L.Fernandez • CERN: F.Zimmermann,D.Schulte [EUROTeV] • DESY: I.Zagorodnov [EUROTeV] • Lancaster: J.Smith,A.Sopczak • Manchester: R.Barlow,A.Bungau,G.Kourevlev, A.Mercer, R.Jones • TEMF, Darmstadt: M.Kärkkäinen,W.Müller,T.Weiland [EUROTeV] • For ESA tests, working closely with • F.Jackson (CCLRC)on optics for wakefield and beam damage studies • M.Woods, P.Tenenbaum, R.Arnold, +…(SLAC)for all aspects • For evolving damage studies, L.Keller, M.Ross, M.Seidel, DESY/SLAC/… Project web: http://hepunx.rl.ac.uk/swmd/

  5. 1500mm ESA – Experimental tests Procedure:(P.Tenenbaum) - insert collimators in beam path (x mover) - move collimator vertically (y mover) - measure centroid kick to beam via BPMs - Analyse kick angle vs collimator position • Commissioning: 4-9 Jan 2006 (4 old collimators) - Successful • Physics: 24 Apr – 8 May (8 new collimators – CCLRC) • People: N. Watson, J. Smith, C.Beard, L. Fernandez, A.Sopczak, F.Jackson Next run : 3 – 17 Jul 2006

  6. ESA View upstream from 3BPM9-11 View downstream from 3C2

  7. ESA View downstream from the 3WS2 3BPM 3-5

  8. ESA – the collimators • Collimators made at RAL (J.Greenhalg, J. O’Dell) • The full set of collimators is at SLAC (four of • these are in the sandwich box, second • sandwich yet to be prepared) • Carry out a swap of the sandwiches at the • beamline -> measurements with 8 collimators • within 2 weeks is a big step forward • Commissioning run starts on 24 April

  9. Wakefields – Gdfidl / Mafia (J.Smith - Lancaster, C. Beard -Astec) • Gdfidl/Mafia simulationsof longitudinal wakes are in acceptable agreement ( Cho’s results (EPAC paper) – still to be understood; result of assumed symmetry ?) • Performed comparison with ABCI for very simple configurations (pillbox cavity as test, with varying bunch length) • + R.Jones (expertise in this field area) However • Short timescale for getting results to compare with test data at SLAC, even shorter for prediction of kicks

  10. Wakefields in Merlin The Existing Code: • Wakefield formalism implemented in Merlin • Wakefield effects previously studied by R.Barlow, G. Kourevlev, A. Mercer • SLAC tests were simulated -> good agreement with the data when higher order modes are included • But : the wakepotential – the same for all accelerator components

  11. Wakefields in Merlin r’, θ’ Changes and Additions to the Code: Cm = ∑ r’m cos (mθ’) Sm = ∑ r’m sin (mθ’) wL = ∑ W’m (s) rm [Cm cos (mθ) – Sm sin (mθ)] wX = ∑ mWm (s) rm-1 {Cm cos [(m-1)θ] – Sm sin[ (m-1)θ]} wY = ∑ mWm (s) rm-1 {Sm cos [(m-1)θ] – Cm sin[ (m-1)θ]} • define new derived classes : SpoilerWakeProcess (Cm, Sm), WakePotentials (aperture information), SpoilerWakePotentials (longitudinal and transverse wakes) • Work currently ongoing (A.Bungau, R.Barlow) s z r, θ

  12. Material Damage – Geant4 /Fluka Simulate energy deposits (Fluka – L.Fernandez, Geant4 – A.Bungau) ->instantaneous T rise Beam profile as in ILC FF9 optics at SP2/4 locations Various spoiler design considered (solid material/combination of two materials) Results passed on for transient state studies • Discussions started with • L.Keller (Nov 2005) • Agreement between three • codes: EGS/Fluka/Geant4 0.6 Xo of Ti alloy leading taper (gold), graphite (blue), 1 mm thick layer of Ti alloy 0.3 Xo of Ti alloy each side, central graphite part (blue). [L.Fernandez, ASTeC] A.Bungau (Manchester)

  13. Material Damage - ANSYS • Study of steady/transient state heating effects: • used Edep from Fluka/Geant4 • good agreement between simulation • and analytic calculations • predicted the stress induced in a 3d • solid (variation with different spoiler • geometries and beam impact • locations) G. Ellwood (RAL) • Studies from beam damage compiled into a proposal • To be discussed with people from SLAC/DESY • Various EPAC’06 abstracts were submitted • EUROTeV reports submitted for review (Fluka and Geant4 studies)

  14. Future Plans • Analyse the data from the first round of tests 24/4 – 08/05 • Compare with analytic calculations and e.m. simulations • Design/build a new set of collimators to test at ESA (input also from ECHO-3D code) • Extend the damage simulations into real experimental tests with beam • Post-April 2007 : development of real collimators (not just jaws material+geometry)

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