Multiply charged ion source based on high current short pulse vacuum arc

Abstract

In vacuum arc ion source, the ion charge states of the extracted beam were elevated by using high current and short pulse mode of arc. The beam of heavy metal ions of several microseconds duration with pulsed beam current of more than 100 mA and mean ion charge state of more than 10+ was generated. Measurements of ion mass-to-charge ratio of ion beam, and images of vacuum arc plasma within the ion source taken with nanosecond resolution prove that higher charge state ions are produced at characteristic distances of ∼10 mm from the cathode as the arc current peaks, and the process responsible for their generation is additional ionization as the discharge is pinched by its self-magnetic field. For bismuth ion beam, the maximum charge state reaches a value of 17+, which is a record-breaking for the vacuum arc ion source.