Optogalvanic spectroscopy applied to the study of hollow cathode discharges devices

Doppler free two-photon optogalvanic spectroscopy has been applied to measure the electric field strength in the cathode fall region of a hollow cathode discharge, via the Stark splitting of the 2S level of atomic hydrogen. Important improvements in the experimental arrangement and in our understanding of the discharge, have allowed us to measure accurately the dependence of the electric field with different parameters like the cathode material (stainless steel and tungsten), geometry (10 and 15 mm inner diameter) and the buffer gas. The study is done for different pressures and currents. The first results seem to reveal different behaviour in the electric field, depending on the material and geometry of the cathode and the discharge conditions.