Vacuum arc ion sources for particle accelerators and ion implantation

The vacuum arc is a generator of highly ionized metal plasma. This method of plasma production can be used to construct a high-current metal ion source. A succession of such metal-vapor vacuum arc ion sources has been developed at Berkeley. Beams from 50 of the solid metals of the periodic table have been produced with mean ion energy up to several hundred keV, and with pulsed beam currents in the ampere range. Typically the source is repetitively pulsed with a pulse length of 250 μs and a duty cycle of the order of 1%. A DC embodiment from which a large-area titanium beam with steady-state ion current of 600 mA was produced has been tested. A 50-cm-diameter set of beam formation grids has been used to form a beam of area 1000 cm² at an energy of 100 keV and a pulsed beam current of approximately 10 A. The source can also be seen as a tool for the study of vacuum arc plasmas. Vacuum arc ion charge state distributions have been studied in this way. The general features and performance characteristics of the sources and their use for accelerator injection and ion implantation applications are described