ABSTRACT
Up to now, we have considered only the electrodynamics of a single particle, or of a plasma in the approximation in which each species may be regarded as a continuous (and usually pressureless) charged fluid. For the remainder of the book we investigate those properties of plasmas for which the thermal distribution of velocities must be taken into account. We begin by setting up the means of describing this velocity distribution and an equation for calculating its approximate development in time. In doing so, we shall proceed rather intuitively, postponing the detailed discussion of the approximation involved. Later, in Chapter 12, we shall reconsider this question in a much more fundamental way. This order of presentation is not, therefore, the most direct, but it has the advantage that both the physical ideas and the mathematical methods developed in the meantime will themselves be found to be very helpful in the more complex fundamental discussion.
