Moderate pressure plasma source of nonthermal electrons

Abstract

Plasma sources of electrons offer control of gas and surface chemistry without the need for complex vacuum systems. The plasma electron source presented here is based on a cold cathode glow discharge (GD) operating in a dc steady state mode in a moderate pressure range of 2-10 torr. Ioninduced secondary electron emission is the source of electrons accelerated to high energies in the cathode sheath potential. The source geometry is a key to the availability and the extraction of the nonthermal portion of the electron population. The source consists of a flat and a cylindrical electrode, 1 mm apart. Our estimates show that the length of the cathode sheath in the plasma source is commensurate (~0.5-1 mm) with the interelectrode distance so the GD operates in an obstructed regime without a positive column. Estimations of the electron energy relaxation confirm the nonlocal nature of this GD, hence the nonthermal portion of the electron population is available for extraction outside of the source. The use of a cylindrical anode presents a simple and promising method of extracting the high energy portion of the electron population. Langmuir probe measurements and optical emission spectroscopy confirm the presence of electrons with energies ~15 eV outside of the source. These electrons become available for surface modification and radical production outside of the source. The extraction of the electrons of specific energies by varying the anode geometry opens exciting opportunities for future exploration.

The effect of nonlinear acoustic oscillations on the current-voltage characteristics of a glow discharge

“…Glow discharge is widely used in practice. In lighting devices, gas lasers, electron sources, plasma-chemical reactors, devices for the synthesis of micro-and nanoscale objects and other applications [1][2][3][4][5][6][7][8][9][10].…”