Author: Keelan, M.
Paper Title Page
THPPD077 ISIS Injector 2 MW Pulsed RF System Power Supply Upgrade 3695
  • R.J. Anderson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • M. Keelan
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  The ISIS pulsed neutron and muon source uses a 4-stage 70 Mev linear accelerator powered by TH116 triode valves. The TH116 anode supply capacitor banks have until recently been supplied by conventional 6-pulse silicon controlled rectifier (SCR) bridges delivering up to 40 kV at 5 A direct current. This dated system has become increasingly difficult to maintain. Early trials of an upgraded system using modern, compact, capacitor charging, switch mode supplies (SMPSs) resulted in severe supply power quality issues due to the pulsed nature of the current demanded from the capacitor banks. Measurements and Spice simulations of the old and replacement supplies allowed the power quality issues to be investigated and an additional external-to-the-SMPS regulator control loop to be developed. The new SMPSs operating with the additional control loop have been tested successfully on several of the linear accelerator stages and are now in continuous operational use. The process of replacing all the original SCR 6-pulse bridges is now well advanced and the operational benefits for ISIS are becoming evident.