Bunching and chopping for tandem accelerators. Part II: Chopping

A chopping system of a tandem accelerator based on two pairs of parallel plates is investigated. The first chopper operating at 37.5 MHz cuts off the tails of the bunched beam and the second, at a lower frequency of 4.6875 MHz, eliminates the satellite low intensity pulses. The experimental procedures for measurement of the performance of a chopping system including a Beam Profile Monitor (BPM) technique and a pulsed beam diagnostic monitor are described. The results of simulations and experimental observations are presented. An analytical technique to reconstruct the real profile of deflected beams from the profile measured with a BPM is discussed in detail. Theoretical and experimental data on the chopper scanning window are presented. An analyses of the factors limiting the chopping system performance is conducted and technical solutions to overcome it are discussed.his work has been supported by the Australian Federal Government Superscience/EIF funding and the NCRIS HIA capability