• S. Hesselbach, G.A. Moortgat-Pick
  Durham University, Durham
• I.R. Bailey, L.J. Jenner
  Cockcroft Institute, Warrington, Cheshire
• J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• S. Riemann, A. Schälicke, A. Ushakov
  DESY Zeuthen, Zeuthen
• J. Rochford
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• L. Zang
  The University of Liverpool, Liverpool

Energy deposition in the conversion targets of positron sources for future linear colliders will lead to thermal shock waves which could limit the targets' lifetimes. For the International Linear Collider baseline source, we have studied the energy deposition in a target taking the higher harmonics of the undulator radiation fully into account and applying hydrodynamical models for the resulting heat flow to determine the thermal stress in the target and to assess its survivability.

• J. Rochford
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• I.R. Bailey
  Lancaster University, Lancaster
• E. Baynham, T.W. Bradshaw, A.J. Brummitt, D.A. Burton, F.S. Carr, A.J. Lintern
  STFC/RAL, Chilton, Didcot, Oxon
• J.A. Clarke, O.B. Malyshev, D.J. Scott, B.J.A. Shepherd
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• Y. Ivanyushenkov
  ANL, Argonne
• G.A. Moortgat-Pick
  Durham University, Durham
• N.C. Ryder
  University of Bristol, Bristol

The ILC positron source relies upon a ~200 m long superconducting helical undulator in order to generate the huge flux of gamma photons required. The period is only 11.5 mm but the field strength is ~1 T. The UK is building and testing a full scale 4 m long ILC cryomodule at the moment. It will be completed in 2008 and the results used to demonstrate the feasibility of the full (200 m long) system.

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