Optogalvanic Measurement of the Cathode-Fall Region of Kr Hollow Cathode Discharge

Abstract

Optogalvanic observation of the Stark shift of the Kr 8d[3/2]₂⁰-5p[3/2]₂ atomic line has been carried out on a Kr hollow cathode discharge in a discharge tube with a cylindrical cathode, at a fill pressure of 1 to 6 Torr (1 Torr = 133.322 Pa), and a discharge current from 1 to 10 mA, to reveal the linear decrease of electric field with radial distance from the cathode surface. Values of current density, charge density, and other discharge parameters have been derived and their behavior has been compared with theoretical formula; it is concluded that a major role is played by the photons from the negative-glow region. Unusual features observed in the discharge at 1 Torr pressure and above 5 mA of current have been attributed to the effect of Penning ionization of sputtered copper atoms.