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Davies, K. P.

Paper Title Page
MOPP069 A Prototype Target Wheel for the ILC Positron Source 706
 
  • I. R. Bailey, L. J. Jenner, C. J. Nelson
    Liverpool University, Science Faculty, Liverpool
  • I. R. Bailey
    Cockcroft Institute, Warrington, Cheshire
  • D. G. Clarke, K. P. Davies, A. Gallagher
    STFC/DL, Daresbury, Warrington, Cheshire
  • J. A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. Gronberg, L. B. Hagler, W. T. Piggott
    LLNL, Livermore, California
 
  In this paper we describe the design, construction and commissioning of a prototype based on the positron production target wheel planned for the ILC positron source. The efficiency of the current baseline positron source design for the ILC can be improved if the conversion target is partially immersed in the magnetic field of the capture optics, thereby increasing the overall capture efficiency for positrons by a factor of two or more. However, immersion of the rotating target wheel generates strong eddy currents leading to additional heating and stresses on the wheel. The primary purpose of our prototype, which had been assembled at Daresbury Laboratory, is to investigate the effects of eddy currents induced in a titanium alloy wheel moving with rim speeds up to 100 metres per second in magnetic fields of the order of 1 Tesla.  
MOPP072 A Study of Mechanical and Magnetic Issues for a Prototype Positron Source Target 715
 
  • L. J. Jenner, I. R. Bailey
    Cockcroft Institute, Warrington, Cheshire
  • D. G. Clarke, K. P. Davies, A. Gallagher
    STFC/DL, Daresbury, Warrington, Cheshire
  • J. A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. Gronberg, L. B. Hagler, W. T. Piggott
    LLNL, Livermore, California
  • S. Hesselbach
    Durham University, Durham
  • C. J. Nelson
    STFC/RAL, Chilton, Didcot, Oxon
  • J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
 
  In order to construct a high yield, positron source that can meet the intensity requirements of future facilities, a robust conversion target is needed. One solution is to use a rotating titanium alloy wheel upon which a beam of photons is incident. The efficiency of capturing the resulting positrons can be optimised by immersing this system in a magnetic field. As described elsewhere*, a prototype of such a target has been built at Daresbury Laboratory, to investigate the mechanical challenges associated with its construction and to study the magnetic effects that the wheel will experience. In this paper, calibration of the instrumentation, the data acquisition system and the initial results from operating the wheel in a strong magnetic field are described. Such phenomena as the eddy current heating experienced by the wheel are measured and compared to results from modelling codes. Vibrational issues surrounding the wheel and supporting structure at various speeds are studied.

*ID: 3894 A Prototype Target Wheel for the ILC Positron Source