Design of a drift tube linac for the ISAC project at TRIUMF

The ISAC radioactive ion beam facility under construction at TRIUMF combines an isotope-separator-on-line with a post accelerator. Required in the accelerator chain is a drift tube linac capable of accelerating unstable nuclei with a post stripper charge to mass ratio of ≥ 1/6 from E = 0.15MeV/u to a final energy fully variable up to 1.5 MeV/u. Due to the relatively low intensities of some of the ion species continuous (cw) operation of the accelerator is required. A five tank interdigital H-type structure, operating at 105 MHz, has been chosen. The beam dynamics conceptual design and the results of various particle simulations are presented. Computer modelling of the rf structure and model measurements have been completed and are reported. (author)