Plasma Science: From Fundamental Research to Technological Applications (1995)
Chapter: INTRODUCTION AND BACKGROUND
2
Nonneutral Plasmas
INTRODUCTION AND BACKGROUND
A nonneutral plasma is a many-body collection of charged particles in which there is not overall charge neutrality. Such systems are characterized by self-electric fields and, in high-current configurations, self-generated magnetic fields. Single-component plasmas are an important class of nonneutral plasmas, the most common examples of which are pure electron and pure ion plasmas. For single-component plasmas in cylindrical geometry, there exists a stringent confinement theorem. The practical consequence of this theorem is that, in contrast to electrically neutral plasmas, a magnetized single-component plasma can be confined easily for very long times (e.g., hours). Therefore, thermal equilibrium and controlled departures from equilibrium can be achieved readily. Nonneutral plasmas exhibit a broad range of collective plasma behavior, such as plasma waves, instabilities, and Debye shielding. Moreover, the rotation and self-generated fields in these plasmas can have a significant effect on plasma properties and stability behavior.
In addition to their importance in understanding fundamental aspects of the behavior of many-body charged-particle systems, there are many practical applications of nonneutral plasmas. Examples discussed elsewhere in this report include the generation of coherent radiation by intense charged-particle beams, the development of advanced accelerator concepts, and the stability of electron and ion flow in high-voltage diodes. Other applications include particle-beam fusion, and the stability and propagation of intense charged-particle beams through background plasma or through the atmosphere. This section focuses
