BROAD-BEAM MULTI-AMPERE METAL-ION SOURCE

An embodiment of the MEVVA (metal vapor vacuum arc) high current metal ion source has been developed in which the beam is formed from a 10-cm-diam set of extractor grids and which produces a peak beam current of up to several amperes. The source, MEVVA V, operates in a pulsed mode with a pulsewidth, at present, of 0.25 ms and a repetition rate of up to several tens of pulses per second (power supply limited). The multi-cathode feature that was developed for the prior source version, MEVVA IV, has been incorporated here also; one can switch among any of 18 separate cathodes and thus metallic beam species. Maximum beam extraction voltage is over 90 kV, and since the ion charge states are typically from Q=1 to 5, depending on the metal employed, the ion energy in the extracted beam can thus be up to several hundred keV. This source is a new addition to the MEVVA family of metal ion sources, and we are at present investigating the operational regimes and the limits to the source performance. In this article we describe the source, and present some preliminary results.