Oscillations of Electron Cloud in External Fields

Abstract

The collective behavior of density fluctuations in a purely electronic cloud which is not neutralized by positive ions is analysed under the influence of external electromagnetic fields. In an equilibrium state the electrostatic space charge force is counter-balanced by the external fields and it gives rise to the mean drift flow of electronic cloud accompanying with the oscillations similar to those in the usual plasma. The classical description lead to the dispersion relation, which involves additional terms due to the drift velocity of electron flow. The effect of this drift velocity on the frequency shift is briefly discussed.