ABSTRACT
This chapter summarizes the basic parameters and characteristics of the plasma medium. It discusses the ionization phenomena — the ways in which the ionized plasma may be formed from the neutral medium. The various ways in which the ionization can be done include electron impact ionization, photoionization, field ionization, and surface ionization. Plasmas have a number of natural modes of oscillation, perhaps the most fundamental of which are the electron plasma oscillations — the response of the plasma to small departures from complete charge neutrality. These are oscillations of the plasma electron component, and the oscillation frequency is called the electron plasma frequency. The chapter also summarizes some of the characteristics of the plasma boundary and plasma behavior in magnetic fields. The behavior of a plasma in a magnetic field can be profoundly different from a plasma in the absence of a magnetic field.
