Simple design criterion for high-intensity hadron linacs

A simple procedure is established to optimize fundamental design parameters of a high-intensity hadron linac where interparticle Coulomb interaction plays a crucial role. Based on the recently proposed semi-empirical resonance condition, a stability map is constructed which reveals potentially dangerous operating regions in tune space. The map is shown to be consistent with numerical data obtained from more complicated approaches. The effectiveness of the new design scheme is demonstrated through systematic particle-in-cell simulations assuming the most typical structure of an Alvarez-type drift tube linac. The present results suggest that the so-called equipartitioning condition, which has often been taken very seriously in high-intensity linac designs, is not necessarily met to guarantee the best machine performance. The basic design concept described here can be applied not only to linacs but also to circular machines.