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

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spoiler wakefields and mechanical design
SPOILER WAKEFIELDS and MECHANICAL DESIGN

Adriana Bungau

The University of Manchester

Manchester, 24/04/2006

outline
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

motivation

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

people
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/

esa experimental tests

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

slide6
ESA

View upstream from 3BPM9-11

View downstream from 3C2

slide7
ESA

View downstream from the 3WS2

3BPM 3-5

esa the collimators
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
wakefields gdfidl mafia
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
wakefields in merlin
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
wakefields in merlin1
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

material damage geant4 fluka
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)

material damage ansys
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)
future plans
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)