H- ion source development for the FNAL 750keV injector upgrade

The new FNAL 750keV injector upgrade for the replacement of the 40 year old Fermi National Laboratory (FNAL) Cockcroft-Walton accelerators with a new ion source and 200MHz Radio Frequency Quadrupole (RFQ), Low Energy Beam Transport (LEBT) and Medium Energy Beam Transport (MEBT) [1], has been built and is now being tested prior to installation during the 2012 shutdown. The new H^- ion source is a round aperture magnetron which was developed at Brookhaven National Lab (BNL) by Jim Alessi[2]. Operational experience from BNL has shown that this type of source is more reliable with a longer lifetime (on the order of 6 to 9 months) due to better power efficiency. With a similar duty factor to BNL, we expect to have a comparable lifetime between source changes. The new source design reliably produces 90mA of H^- beam current at 15Hz rep-rate, 250μs pulse width, and a duty factor of 0.38%. The measured emittances at the end of the LEBT are horizontally ∊_H = 0.21π mm* mrad and vertically ∊_V = 0.17π mm* mrad. With 35kV extraction the power efficiency is 60mA/kW. The source design, along with data from a test stand and the LEBT, will be presented in this paper.