FRIB, East Lansing, Michigan, USA
As a follow-up study to the initial design of FRIB Loss Monitor Ring (previously named Halo Monitor Ring [1]), we present recent results of coupling studies between the FRIB CW beam and the Loss Monitor Ring (LMR). While a ~33 kHz low-pass filter was proposed to attenuate high-frequency AC-coupled signals [1,2], the LMR current signal may still contain low frequency signals induced by the un-intercepted beam, for example, by the 50μs beam notch that repeats every 10ms. We use CST Microwave Studio to simulate the AC response of a Gaussian source signal and benchmarked it to analytical model. A circuit model for beam-notch-induced AC signal is deduced and should put a ~33pA (peak) bipolar pulse on the LMR at 100Hz repetition rate. Although its amplitude falls into our tolerable region, we could consider an extended background integration to eliminate this effect.
