Fast ion bunch compression by barrier pulse control

We report a novel scheme for fast ion bunch compression by barrier pulse control in an induction synchrotron in which an effective acceleration voltage pulse with a pseudo-linear slope is generated by temporal handling of rectangular induction acceleration pulses. With beam handling, a head-to-tail momentum gradient is yielded to the beam in a desired manner and the beam is gradually compressed over 30 turns. In the proof-of-principle experiment, which used a 75 μA He$^{1+}$ beam at 50 keV per nucleon, the root mean square bunch length was reduced to 0.44 μs by a factor of 3.5 in 30 turns with no appreciable beam loss due to the beam compression scheme. This scheme is useful for various beam applications including ion beam heating.