Injection optimization in a heavy-ion synchrotron using genetic algorithms

Abstract

The control of the beam loss induced dynamic pressure is one of the most challenging problems for synchrotrons operated with high intensity beams of intermediate charge state ions. This loss-induced vacuum degradation and associated life-time reduction is one of the key intensity limiting factors. Beam loss during Multi-Turn Injection (MTI) can trigger the pressure bump instability. An optimized injection can relax the dynamic vacuum problem, but is also crucial to fill the available machine acceptance. A numerical model has been developed to describe the intensity limitation due to loss-induced vacuum degradation. In order to optimize the multi-turn injection for given initial losses, a genetic algorithm based optimization has been performed. For the SIS18 synchrotron at GSI the optimization resulted in a significant improvement of MTI performance and subsequent transmission for intense beams. A range of suitable injector brilliances for given initial loss could be defined. This information is crucial for the layout of the injector upgrade for FAIR. The effect of transverse space charge force on MTI has been included in the optimization studies.