High field transport phenomena in point-plane geometry in liquid helium

Conductivity and ionization phenomena in liquid helium have been investigated by using high field conduction phenomena occurring near sharp needle electrode. When the voltage V applied between the needle and the plane is greater than threshold voltage V_s, a corona-like regime was observed. Above V_s the mean current is space charge limited. The mobility of charge carriers has been deduced from analysis of current-voltage characteristics. Charge carriers are generated in the high field region close to the point where an intense light emission is detected. The simultaneous measurement of electrical and optical signals linked to a spectral analysis of the emitted light were used to determine the possible mechanisms involved in charge generation.