He3-Limited Drift of Charge Carriers in SuperfluidHe4(0.3<T<1.0°K)

Abstract

Measurements were made of the mobility of positive and negative charge carriers in ${\mathrm{He}}^{4}$, for ${\mathrm{He}}^{3}$ impurity concentrations ranging from 10 to 1800 ppm and temperatures in the range $0.3<T<1.0\ifmmode^\circ\else\textdegree\fi{}$K. The excess inverse mobility $\frac{e}{\ensuremath{\mu}}\ensuremath{-}\frac{e}{{\ensuremath{\mu}}_{0}}$ was everywhere found to vary linearly with concentration, as expected. For negative carriers, the data are well explained by a hardsphere scattering model with a collision radius of 21 \AA{}. For positive carriers, the polarization-deficit potential proposed by Bowley and Lekner gives reasonable agreement with experiment, provided a collision radius of 7.0 \AA{} is assumed.