BEHAVIOR OF CURRENT IN GAS-DISCHARGE SYSTEM BETWEEN PARALLEL-PLANE ELECTRODES

The current-voltage characteristics of a gas discharge system in paral lel-plane geometry are studied. The gas discharge system with a photos ensitive semiconductor cathode have been studied in a wide range of th e gas pressures p (21.3 - 1013 hPa), inter-electrode distances d (10 m u m - 5 mm), and conductivities of the semiconductor. Gallium arsenide (10(7) - 10(8) Omega cm) has been used as the semiconducting cathode. The cathode was irradiated on the back-side with light in a particula r wavelength range that was used to control the photoconductivity of t he material. The semiconductor material was found to ''stabilize'' the discharge. When the current is increased above the stable limit, brea kdown or small current oscillations begin. The filamentation was prima ry due to the formation of a space charge of positive ions in the disc harge gap which changed the discharge from the Townsend to the glow ty pe.