• S. An, S.M. Wei, T.J. Zhang
  CIAE, Beijing
• K. Bongardt
  FZJ, Jülich

The 10 mA, 40keV H^- pulsed injection line for the CIAE 10 MeV CRM cyclotron has two main operation modes for bunched beams: delivering 5 mA CW beam or chopped pulse with more than 100uA. Chopped pulse is achieved by placing behind the 70.5 MHz bunching cavity a sinusoidal transverse deflecting cavity with frequency of 2.2 MHz, 1/32 of the bunching frequency. Particles outside the wanted ±3° phase width @ 2.2 MHz, corresponding to ±90° @ 70.5 MHz, are either absorbed in a 50cm drift after chopper or at round slit1, 1cm aperture. Time dependence of sinusoidal chopping field causes RMS emittance increase by a factor 3 and changes twiss parameter alpha by a factor 2 before the round slit1. Solenoid couples motion in transversal planes, but equalizes both RMS emittances. Particle tracking results are presented for the chopped pulse, showing longitudinal-transverse coupling in the deflector and equalization of RMS emittances in the solenoid. Optimised focusing strength leads to about 1 % transmission efficiency for the chopped pulse. The CRM inflector receives 2.4 ns long pulse at about 4.4 MHz repetition rate, 1/16 of the RF frequency.