Optogalvanic spectroscopy and thermal relaxation in high-pressure mercury and sodium arc discharges

Abstract
Thermal relaxation processes in high‐pressure Hg and Na arc discharges have been studied by measuring the frequency dependence of the optogalvanic effect up to 5000 Hz. The experimental results are interpreted in terms of two linear relaxation processes, using a simple model for the energy flow in the arc. For the Hg arc (400 W dc) the two characteristic times are found to be 4.0×10−4 s and ?4×10−6 s. For the Na arc (180 W dc) only one characteristic time of 5.3×10−5 s is obtained.