Pressure Dependence of Charge Carrier Mobilities in Superfluid Helium

Abstract

Accurate and extensive measurements were made of the mobility of positive and negative charge carriers in 4He at pressures up to the melting pressure and temperatures in the range 0.27 < T < 1°K. The data are analyzed in terms of the scattering of phonons and rotons by the carriers. The phonon-dominated mobility of the negatives agrees well with existing theories, and analysis of our results provides a new determination of the electron bubble radius as a function of pressure. The phonon term for the positives is calculated from the electrostriction model and is in good agreement with the experimental results.