• P.-A. Duperrex, P. Baumann, S. Joray, D.C. Kiselev, Y. Lee, U. Müller
  PSI, Villigen

A new current monitor has been built and installed during the last maintenance period in prevision of the high intensity beam operation (3mA, 1.8MW) which is planned in the near future. It is a re-entrant cavity tuned at the 2nd RF harmonic (101 MHz). Compared to the current monitors already in operation, the design had to be modified to improve its cooling. Indeed, this monitor is placed 8 m behind a graphite target and is exposed to scattered particles. The resulting heat load would raise the monitor temperature well above 200 deg C without cooling. The modifications include a slightly different structure to improve the heat conduction, a blackening of the external surface to increase the thermal radiation and an active water cooling. Thermocouples placed on the cavity will monitor the temperature of the system. The new design was supported by simulations for heat load resulting from the scattered particles and by calculations concerning the cooling efficiency. Results obtained during laboratory tests and at the beginning of operation will be presented. Comparison between expected heat load and temperature with the actual measured values will be also discussed.