Operational Aspects of the High Current Upgrade at the Unilac

Abstract

With the new GSI High Current Injector, the beam pulse intensity will be increased by more than two orders of magnitude. The high beam power and the short stopping range at particle energies below 12 MeV/u can destroy accelerator components even during a single beam pulse. Therefore, the operation of the whole accelerator facility has required major changes in hardware, software and operating strategy. A sophisticated beam diagnostic system is indispensable for a safe operation. Preferably non-destructive devices were installed. Destructive elements, e.g. beam stoppers, slits, apertures, were improved in order to withstand the high beam power. Automatic damage prevention was realised by beam loss monitors comparing and evaluating very fast beam current transformer signals. Additionally, the component status will be controlled permanently. For foil stripping at 11.4 MeV/u, a magnetic beam sweeping system was installed Thereby, the hit area will be increased during one 100 micro sec pulse. During operation, manual variation of parameters has to be reduced. Set-up and automatic beam adjustment procedures have to exclude uncontrolled beam loss. The versatility of the UNILAC is enhanced by the possible three-beam operation on a pulse-to-pulse basis. Since November 1999 the upgraded UNILAC is serving the experiments.