Plasma generation using a large V-groove cathode discharge

Abstract

The results of an investigation of the plasma parameters generated by a large V-groove cathode discharge are presented. The cathode consists of a twelve inch aluminum plate into which V-grooves of 1/8th inch spacing and 60 deg angle are milled. With this cathode, a negative glow discharge is produced which yields a stable, steady-state plasma. Electron densities up to 2×10¹² cm⁻³ have been obtained in the 12 inch diameter chamber. The electron temperature is about 1200 K and is independent of discharge current and gas pressure over the range, 0.3 to 0.9 Torr.

The discharge operates in the same fashion as a conventional brush cathode discharge but with lower operating voltage for equal current densities. The lower operating voltage which reduces the arcing problems at the cathode-glass junction and the relative ease in fabricating the V-groove cathode make it an attractive alternative to the brush cathode for many applications. It is shown that the plasma is beam generated and the dominant electron loss mechanism in the steady state is electron-ion recombination. However, although most electrons are lost by recombination, diffusion losses still play a strong role in determining the electron density profile.