Continuum flux

Our goal in this chapter is to provide a complete mathematical description of plasmas in motion, and to describe how the motion changes with time in response to applied forces. The equations of motion are the central and most essential part of all simulation computer codes. All the other physical processes operative in matter at extreme conditions – thermal energy transport, radiation energy transport, ionization – affect the motion, and in the simulation code are added as source terms to the basic hydrodynamic equations.

We begin by considering motion in one dimension only. We also start with the simplest case of plasma that is a non-viscous and non-conducting fluid. Of course, real plasmas are both viscous and conducting, and we will learn how to add these descriptions to our mathematical modeling in later chapters. We are concerned with describing the bulk motion of the fluid rather than the thermal motion of the constituent particles, so a continuum fluid description will be adequate. We also assume that the bulk material velocities are much less than the velocity of light, so we can treat the fluid as non-relativistic.