Density dependence of the electrical conductivity of slightly ionised mercury vapour

Abstract

The density dependence of the electrical conductivity of slightly ionised mercury vapour has been measured for the 1520 degrees C supercritical isotherm and the density range from 1.4 to 6 g cm-3. The observed values are in excess of 10-4 ( Omega cm)-1 at the lower densities and exhibit a surprising density dependence. A theoretical model is proposed to interpret the observations; its central element is the thermal generation of a spectrum of molecular ions: Hgl+. The large cohesion of these clusters plays a dominant role in the ionisation balance. Also, estimated limits on the spectrum of l-values can account for the observed density dependence.