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Appelbee, C. W.

Paper Title Page
MOPAN104 Current Monitor for the ISIS Synchrotron RF Cavity Bias Regulator 407
 
  • A. Daly
    STFC/RAL, Chilton, Didcot, Oxon
  • C. W. Appelbee, D. Bayley
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
 
  The ISIS facility at the Rutherford Appleton Laboratory in the UK is currently the world's most intense pulsed neutron source. The accelerator consists of a 70 MeV H- Linac and an 800 MeV, 50 Hz, proton Synchrotron. The synchrotron beam is accelerated using six, ferrite loaded, RF cavities each having its own high voltage r.f. drive amplifier and bias system. Each of these cavities is driven as a high Q tuned r.f. circuit; the resonant frequency being controlled by passing a current through a bias winding. This current comes from the Bias Regulator system which consists in part of eight banks of 40 transistors. This paper describes the design of a system which will use digital techniques to monitor and display the current of each of the 320 transistors in the Bias Regulator system.  
TUPAN117 Progress on Dual Harmonic Acceleration on the ISIS Synchrotron 1649
 
  • A. Seville, D. J. Adams, C. W. Appelbee, D. Bayley, N. E. Farthing, I. S.K. Gardner, M. G. Glover, B. G. Pine, J. W.G. Thomason, C. M. Warsop
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
 
  The ISIS facility at the Rutherford Appleton Laboratory in the UK is currently the most intense pulsed, spallation, neutron source. The accelerator consists of a 70 MeV H- linac and an 800 MeV, 50 Hz, rapid cycling, proton synchrotron. The synchrotron beam intensity is 2.5·1013 protons per pulse, corresponding to a mean current of 200 μA. The synchrotron beam is accelerated using six, ferrite loaded, RF cavities with harmonic number 2. Four additional, harmonic number 4, cavities have been installed to increase the beam bunching factor with the potential of raising the operating current to 300μA. The dual harmonic system has now been used operationally for the first time, running reliably throughout the last ISIS user cycle of 2006. This paper reports on the hardware commissioning, beam tests and improved operational results obtained so far with dual harmonic acceleration.  
WEPMN076 Digital Master Oscillator Results for the ISIS Synchrotron 2203
 
  • C. W. Appelbee, A. Seville
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • A. Daly
    STFC/RAL, Chilton, Didcot, Oxon
 
  Rutherford Appleton Laboratory in Oxfordshire is home to an 800MeV synchrotron particle accelerator called ISIS. Its main function is to direct a beam of protons into a heavy metal target to produce neutrons for scientists to analyse condensed matter. A second harmonic system is being developed to upgrade the beam current from 200uA to 300uA in order to drive a second target station. This is being achieved by the inclusion of four second harmonic cavities to increase the width of the RF bucket. In the past the six fundamental cavities were driven by an analogue master oscillator but the extra cavities will bring more difficultly in the phasing of the system. This could be more easily and precisely controlled by embedding a Direct Digital Synthesis core into an FPGA chip as the heart of a new digital Master Oscillator. This paper describes the results of the setting up and performance of the prototype instrument and the implications it has for the synchrotron.