Upgrade and Improvement of the TRIUMF ECRIS Charge State Booster

Abstract

Recently, the RF system of the TRIUMF electron cyclotron resonance ion source charge state booster (ECRIS CSB) underwent an upgrade to implement two-frequency heating using a single waveguide. The injection and extraction optics, as well as the injection and extraction systems, were carefully modelled and systematically optimized to improve the efficiency and beam quality of the charge state booster. With optimized plasma and beam optics under the single-frequency heating regime, the maximum charge state of the 133Cs isotope produced was 27+, with the peak of the charge state distribution at Cs23+ with an efficiency of 8.5 %. However, with the implementation of two-frequency heating, the maximum charge state of Cs that can be produced increased to 32+, and the charge state distribution’s peak shifted to Cs26+ with an efficiency of 9.1 %. Additionally, the two-frequency heating resulted in a total beam RMS emittance that was approximately half of the one that was measured under the single-frequency heating due to the more pronounced negative potential dip created at the plasma center.