Injection of Electrons into He II from an Immersed Tungsten Filament

Abstract

Tungsten filaments have been operated while immersed in He II at temperatures up to 2500\ifmmode^\circ\else\textdegree\fi{}K, and electron currents as high as 0.5 \ensuremath{\mu}A have been produced in the superfluid, yielding densities of at least ${10}^{9}$ negative ions/${\mathrm{cm}}^{3}$. The fluid in the vicinity of the filament remains quiescent under these conditions as a result of a stable vapor film which forms around the filament.