AN ACCELERATOR FOR ALKALI-METAL PLASMAS

A washer plasma gun for alkali-metal plasma is developed. This gun is suitable as a source for experiments on alkali-metal plasmas, plasma d iagnostics, and in various applications such as ion-beam sputter depos ition. The gun uses an injector of alkali-metal vapor based on the pri nciples of laser ablation. Acceleration is performed by a large electr ical field provided across eight washers. The gun is compact, stable, and easy to fabricate and use. The gun produces a neutral Li0 beam cur rent of 1 A/cm2 and a Li+ ion current of 50 A/cm2 at its exit at 10 kV of capacitor bank voltage. With this intensity, it is possible to pro duce beams of neutral Li0 atoms of density 6 X 10(9) cm-3 and Li+ ions of density approximately 10(11) cm-3 at 1 m from the gun, moving with a velocity of approximately 10(7) cm/s.