Metal vapor vacuum arc ion sources (invited)

Abstract

High current beams of metal ions can be produced efficiently using a metal vapor vacuum arc to establish the metal plasma from which the beam is formed. Pulsed beam currents of several amperes of metallic ions have been produced from nearly all of the solid metals of the periodic table, and in some recent tests dc beams have been produced also. Beam extraction voltage up to 100 kV has been used and since the ions produced in the vacuum arc plasma are in general multiply ionized the ion energy is up to several hundred keV. These kinds of sources are finding application for heavy-ion synchrotron injection, metallurgical ion implantation, and other uses. A number of different embodiments of the source have been developed at Berkeley and elsewhere around the world. Interesting features include multiple cathodes and the ability to switch between up to 18 separate cathode materials simply and quickly, and broad beam source versions (up to 50 cm diameter) as well as miniature versions (about ‘‘thumb size’’). Here we review the design features, operational behavior, and beam performance characteristics of these sources from the perspective of the Berkeley program.