Investigation of MEVVA ion source for metal ion injection into accelerators at GSI

Abstract

High current metal ion production is a challenging task for ion source designers. The MEVVA ion source has proven to be a useful tool for accelerator injection and for ion implantation. We have investigated the MEVVA ion source in connection with the GSI heavy ion accelerators. At the Unilac accelerator as injector for the heavy ion Synchrotron SIS (1 Hz and 100 μs pulse length) the MEVVA can deliver mA beams of multiply charged ions up to 3+ (or mass to charge ratio of ≤24 accepted by Unilac). At the 300 kV ion implantation facility the MEVVA is used to inject metal ions into the RFQ accelerator with duty cycles above 1%. Here we discuss the ion beam currents and charge state distributions for various ion species and beam formation and transport at the accelerators. Space-charge effects and ion beam instabilities are discussed in detail. At the Unilac injector results with titanium and nickel from the MEVVA ion source are compared with those of neon from a CHORDIS gas ion source.