A study of stripped pinched-beam transport for heavy ion fusion

One of the alternative scenarios for a heavy ion driver for inertial confinement fusion is final transport as a self-magnetic pinch. A beam is stripped by passing it through a thin foil (or gas) which also supplies neutralizing electrons. The beam is then centered in a long conducting pipe which may be surrounded by a solenoid to help the confinement of neutralizing electrons. Additional electrons are supplied by ionization of a low pressure gas in the pipe. Immediately before the stripping foil a mini final focusing system would be applied, which makes the envelope waist of a few millimetre radius at the foil. In this scheme, the usual chromatic aberration constraint on the heavy ion fusion driver can be relaxed by at least an order of magnitude, which gives substantial relief on the longitudinal beam dynamics issues. A simulation study has been performed using an (r, z) particle-in-cell code for all six electromagnetic field components and the three components of particle velocity.