Investigations of longitudinal hollow-cathode discharge

Abstract

Results of investigations of a longitudinal hollow-cathode discharge are presented for a hollow cathode of 5 mm diameter and a length variable from 8 mm up to 96 mm. Hollow cathodes of such dimensions are used in discharge tubes employed in laser technology. Axial distributions have been determined for the current density over the cathode surface, discharge current intensity and discharge plasma potential. Also voltage vs current discharge characteristics have been measured. The measurements have been carried out for discharge in helium at a pressure ranging from 1.67 hPa to 34 hPa. The current intensity varied from 1.86 mA to 250 mA depending on the cathode length. The investigations covered hollow-cathode discharges in the presence of one anode as well as two anodes located at the opposite ends of the cathode. An axial inhomogeneity of the discharge plasma resulting in nonuniform axial distributions of the cathode and longitudinal currents as well as nonuniform axial distribution of the discharge plasma potential was observed for both cases. The inhomogeneity of the longitudinal hollow-cathode discharge affects the operation of the laser discharge tube. Some consequences of this inhomogeneity are discussed.