Plasmas as Conducting Fluids

Abstract

A plasma is a fluid medium capable of conducting electrical current. Therefore, a simple model for a plasma is the model of a conducting fluid. In this model we do not examine the motion of individual particles; instead, the plasma is assumed to be a continuous medium similar to those that are treated in hydrodynamics. When this simplifying assumption is used there are no differences between liquids and gases. In the absence of ionization the difference between these states of matter lies in the compressibility, gases being much more compressible. However, compressibility is also important in flow phenomena if the flow velocity is near the sound speed. Therefore, ordinary hydrodynamics is the study of the motion of liquids and gases at velocities which are small compared with the speed of sound.