Author: Probert, M.A.
Paper Title Page
WEPC25 Optimisation of a Split Plate Position Monitor for the ISIS Proton Synchrotron 739
  • C.C. Wilcox, J.C. Medland, S.J. Payne, A. Pertica, M.A. Probert
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  A new Beam Position Monitor (BPM) has been designed for the ISIS proton accelerator facility at the Rutherford Appleton Laboratory in the UK. The new monitor, which will be installed in the beam line to Target 1, is of a ‘split plate’ design which utilises two pairs of electrodes to allow the beam position to be measured simultaneously in the horizontal and vertical planes. Simulations carried out using the CST low frequency solver have highlighted the inaccuracies in the measured beam position caused by strong inter-electrode coupling in such a monitor. This coupling, along with imbalanced electrode capacitances, leads to reduced sensitivity to changes in beam position as well as producing a positional offset error. This paper describes how the problems associated with inter-electrode coupling have been removed with the addition of grounded rings placed between each of the four electrodes. The design and positioning of the rings also ensured that the four electrode capacitances were matched. The results are presented both as CST simulations of ‘thin wire’ beam position measurements and results from bench measurements of a prototype dual plane BPM.