4 rod RFQ injectors for the GSI linac

A four-rod RFQ (radio-frequency quadrupole) is being built as a part of the new high charge state injector for the UNILAC at GSI Darmstadt. It will accelerate heavy ions from an ECR (electron cyclotron resonance) ion source with charge-to-mass ratio of q/u>or=0.117 (U/sup 28+/) from 2.5 keV/u to 300 keV/u, which corresponds to an energy gain of 2.5 MeV/q. The four-rod RFQ will be 2.9 m long with a tank diameter of 35 cm and will operate at 108.5 MHz with a duty cycle of up to 50%. The status of the project and first results are presented. In addition, work on a high-current prototype accelerator designed for U/sup 2+/ (25 emA), 2.5 to 25 keV/u, and an operating frequency of 27 MHz is reported.<>