EFFECT OF DISCHARGE CONDITIONS AND CATHODE IDENTITY ON CHARGED-PARTICLE POPULATIONS IN THE NEGATIVE GLOW REGION OF A SIMPLE DIODE GLOW-DISCHARGE

Plasma properties of electron temperature, average electron energy, electron energy distribution function, and electron and positive ion number densities in the negative glow region are determined for a range of discharge conditions for various cathode identities (materials). The results show that the so-called "slow" electrons are heavily populated, with depletion of higher energy electrons, above 1.2 eV. This depletion seems to be caused by atomic excitation collisions. The results also show that the electron temperature and average electron energy are controlled mainly by "fast" electrons. The work function of the cathode plays an important role in the emission of secondary electrons but does not affect significantly the bulk plasma excitation conditions.