End-to-end simulations of an accelerator for heavy ion beam bunching

Longitudinal bunching factors in excess of 70 of a 300- keV, 27-mA K+ ion beam have been demonstrated in the Neutralized Drift Compression Experiment in rough agreement with particle-in-cell end-to-end simulations. These simulations include the ion source temperature, experimental diode voltage and induction bunching module voltage waveforms in order to determine the initial beam longitudinal phase space critical to longitudinal compression. To maximize simultaneous longitudinal and transverse compression, we designed a solenoidal focusing system that compensated for the impact of the applied velocity tilt on the transverse phase space of the beam. Here, pre-formed plasma provides beam neutralization in the last one meter drift region where the beam perveance becomes large. We compare simulation results with the experimental measurements and discuss the contributions to longitudinal and transverse emittance that limit compression.