Collective Plasma Oscillations

Abstract

To start with we shall remind our readers of the elementary description of collective plasma oscillations. We must emphasise that plasma oscillations are excited by the collective motion of many particles, which through simultaneous displacements create a field, rather than by a single particle. Let us consider a quasi-neutral, homogeneous plasma in which at any point the charge of the electrons is cancelled by the charge of the ions. Consider a layer of thickness d and displace the electrons in this layer over a distance δx = d (see Fig.2.1). It is important that all the electrons in the layer δx are displaced over the same distance, as only in this case will the field due to these displacements be created collectively.