Effect of cathode-bore geometry and filler-gas pressure on the observed distribution of sputtered copper atom densities in ahollow-cathode lamp

Abstract

Atomic absorption spectrometry has been used to probe the distribution of sputtered copper atoms in the body of a discharge cell specially constructed to reproduce the environment of a hollow-cathode lamp. Variations in the sputtered atom distribution have been characterized in terms of the absorption value at a Cartesian origin defined at the intersection of the cathode-bore axis and the top of the cathode bore. This value is extrapolated from the dependence of each individual absorption measurement on the corresponding distance from the Cartesian origin. The dependence of this extrapolated value on a range of cathode-bore geometries, current densities and filler-gas pressures has been investigated. This study demonstrates that absorption measurements from the region above the hollow cathode show a self-consistent sensitivity to variations in the glow discharge that result from the variation of cathode-bore geometry and filler-gas pressure. Comment is made upon the applicability of this technique to the assessment of novel cathode materials.