Mobility of Ions in LiquidHe4I andHe3as a Function of Pressure and Temperature

Abstract

In this paper we present an experimental study of the pressure and temperature dependence of the mobility of the positive and negative species of charged particles in liquid ${\mathrm{He}}^4$ above the $\lambda$ transition and in liquid ${\mathrm{He}}^3$. The mobility of the positive species in ${\mathrm{He}}^4$ decreases linearly with increasing density, and the Stokes radius of the positive species is inversely proportional to $T^{\frac{1}{2}}$. The mobility of the negative species initially increases with increasing density and then falls off linearly with further increase in density. The Stokes radius of the negative species increases with increasing temperature. At constant density the mobilities of both species in ${\mathrm{He}}^4$ and ${\mathrm{He}}^3$ vary very slowly with temperature. At the vapor pressure and around 2.2°K there is a larger temperature dependence than indicated above, but this is probably due to the approach of the $\lambda$ transition. The mobility of the positive species in ${\mathrm{He}}^4$ and ${\mathrm{He}}^3$ at 3.0°K is a linear function of density, independent of the isotope.