Oscillation Phenomena of Electron Current in Liquid Helium II

Abstract

Electron bubble current in liquid helium II under a strong pulsed electric field was investigated and a new oscillation phenomenon was found. The frequency was about 0.2∼2 kHz in usual experimental conditions and it depends strongly on temperature and field strength. There is a critical field below which no oscillation is found. A theoretical analysis shows that the phenomenon can be attributed to the space charge bunching effect induced by the field dependent mobility of electron bubble. The mechanism is, to some extent, similar to the Gunn effect in semiconductors such as n-type GaAs.