Further development for the TRIUMF H−/D− multicusp source

We have reported a 15 mA dc H− multicusp source at the sixth International Ion Source Conference in 1995 at Whistler. Since then, the H− beam has been further upgraded to 20 mA for 25 kV dc extraction. The D− beam output of the new cusp source has also been measured at 25 and 12.5 kV energies. An 8 mA D− peak current at 25 kV with 0.5 π mm mrad normalized 4 rms emittance has been obtained. Special attention was given to the effects of gas flow, pumping speed, and neutralization on the 12.5 kV operation which is used for the D− injection into a 15 MeV D− cyclotron. At present, we are making an effort to test the effect of injecting Cs in the vicinity of the plasma aperture. On the other hand, a hybrid of filament plus LaB6 cathode mechanism has been tested for filament lifetime issue. The results from these tests are reported. In particular, the experience in operating this new source for the Triumf/Nordion TR30 cyclotron is summarized.