Synthesis of MBE-4 accelerating waveforms

An ion induction linac for HIF must operate near the space charge current limit along most of its length. Small errors in the voltages applied to the accelerating gaps can readily produce local unwanted beam bunching and consequent beam loss. Uncompensated space charge forces will generate current loss from longitudinal beam spreading. In the design of the MBE-4 ideal acceleration voltages were developed that assure self-similar amplifying current waveforms at each position along the accelerator. These were approximately synthesized by adding waveforms that can be obtained from realizable electrical pulsers. A code is used to study effects produced by the imperfect synthesis on the longitudinal ion dynamics and beam current waveforms in the presence of space-charge forces