Electron mobility and localization in dense He4 gas

Abstract. An extensive experimental investigation has been carried out on the mobility of electrons in dense helium gas with particular emphasis on the drastic decreases in mobility which are believed to result from the onset of electron localization in the fluid. The mobility was measured for gas densities 2 < p < 40 x lo2 ’ atoms cm-3, and for gas temperatures 4 < T < 300 K. Refinements of former treatments of electron localization via the bubble model are presented which demonstrate a strong correlation between the mobility ‘edge ’ and a localiza-tion criterion. Detailed agreement between theory and experiment is not realized, but the general features of the density and temperature dependence of the mobility are reproduced in a consistent manner. 1