ION ENERGY SPREAD AND CURRENT MEASUREMENTS OF THE RF-DRIVEN MULTICUSPION-SOURCE

Axial energy spread and useful beam current of positive ion beams have been carried out using a radio frequency (rf)-driven multicusp ion so urce. Operating the source with a 13.56 MHz induction discharge, the a xial energy spread is found to be approximately 3.2 eV. The extractabl e beam current of the rf-driven source is found to be comparable to th at of filament-discharge sources. With a 0.6 mm diameter extraction ap erture, a positive hydrogen ion beam current density of 80 mA/cm(2) ca n be obtained at a rf input power of 2.5 kW. The expected source lifet ime is much longer than that of filament discharges. (C) 1997 American Institute of Physics.