A proposed high-current nanosecond source of energetic ions

Abstract

Experiments by Friedman (1972), and theoretical analysis by Sudan & Lovelace (1973), Rostoker (1972), Rostoker & Poukey (1971) and Wheeler (1974), considered ion emissionin a vacuum diode. The ions emitted (e.g. in the Friedman experiment) were generated by laser irradiation of the anode. Using this technique, multiply-ionized species could be obtained. The ion currentwas limited non-relativistically to the square root of the mass ratio times the electron current, so that energy transfer to the ions was relatively inefficient. Some improvement was obtained at relativistic electron energies.Sloan & Drummond (1973) proposed a high-current ion accelerator, where the transfer of energy to the ions is achieved by a negative energy cyclotron wave on an intense E beam. Such an accelerator requires an ion source capable of providing several hundred Amperes of protons at energies in the range of a few hundred keV to several MeV. In this article, we propose a suitable ion source for an accelerator.