High-Field Electronic Conduction in Liquid Nitrogen

Conduction characteristics between a needle and a plane electrode in liquid nitrogen (LN2) were investigated when a negative dc voltage was applied to the needle. Both characteristics, the overall time of voltage application T vs current I and the applied voltage V vs current I, showed the onset currents at specific values of applied voltage. On the other hand, it was found that positive triboelectric charge was produced when LN2 was forced through a metal pipe from a Dewar into a cryostat. By applying the Fowler-Nordheim theory, we showed that electron emission from a cathode was greatly influenced by both the layer of positive ions and microscopic projections on the cathode surface. Parameters in the theory concerning the emission of electrons from the cathode have not been made clear, but in this paper, they were investigated and numerically determined.