Simulations of ion dynamics in induction linacs with advanced gap circuit models

The author describes computer simulations of a coasting beam in a periodic multigap accelerator. One advance from previous work is the introduction of shunt capacitance to the gap circuit model. The simulations show that capacitance can stabilize microscopic bunching instabilities. The results give a simple criterion for the value of shunt capacitance to give reduced growth or complete stabilization. A second approach studied for the stabilization of bunching instabilities is the introduction of a coherent energy shift between the beams of a multiple-beam HIF (heavy-ion fusion) transport system. This shift can simulate a broad energy distribution. The simulations show that this approach is successful as long as there is sufficient overlap between the beams in velocity space