A long lifetime ion source with plasma cathode has been developed for use in ion implantation. In this ion source, a plasma of a nonreactive working gas serves as a cathode in place of a thermionic tungsten filament used in the Freeman ion source. In an applied magnetic field, the plasma is convergent, i.e., filamentlike; in zero magnetic field, it turns divergent and spraylike. In the latter case, the plasma exhibits a remarkable ability when the working gas has an ionization potential larger than the feed gas. By any combination of a working gas of either argon or neon and a feed gas of AsF5or PF5, the lifetime of this ion source was found to be more than 90 h with an extraction voltage of 40 kV and the corresponding ion current density 20 mA/cm2. Mass spectrometry results show that this ion source has an ability of generating a considerable amount of As+and P+ions from AsF5and PF5, and hence will be useful for realizing a fully cryopumped ion implanter system. This ion source is also eminently suitable for use in oxygen ion production.