Low-energy ion beam extraction from a hot cathode dc discharge

Abstract

Low-energy argon ions were extracted using a wire extractor geometry from an ion source equipped with a high temperature cathode. Good quality ion beams were produced as long as dilute plasma was present downstream to mitigate space-charge effects. Ion energies were found to depend on the plasma potential (ϕₚ) of the upstream plasma and the extraction potential (ϕext) of the extractors. As ϕₚ increased, the lowest possible energy of ions that can be extracted also increased. When ϕext was beyond 50 V, the ion beams began to diverge irrespective of the discharge current which should be proportional to the plasma density.