A single bunch selector for the next low ß continuous wave heavy ion beam

The MEBT line of EURISOL heavy ion post-accelerator and the SPIRAL2 deuton/ion accelerator should transport a continuous wave (cw) beam from a 88.05 MHz RFQ (ß respectively 0.035 and 0.04) to a drift-tube linac. A high frequency chopper is being studied to select only 1 bunch over N, respectively 10 < N and 100 < N as asked by the physicists. It requires pulse voltages up to 2.5k kV, rising in less than 6 ns at a repetition rate up to 8.8 MHz. These figures are at the border of what can be provided by the travelling wave fast choppers and the capacitive-type chopping technologies [1,2,3,4]. We have reviewed the current fast and slow chopping structures and their associated pulse generator [5]. Some preliminary RF simulations to adapt the present chopping devices to our requirements are presented. The main limitations of these technologies when applied to select one bunch in cw ion accelerators are also shown. Our first studies and results to solve the arising problems are discussed.