This book is intended as an introduction to the theory of plasma instabilities. It is directed at graduate students, advanced undergraduate students with some background knowledge of plasma physics, and to researchers seeking to become more familiar with the field.

In most applications of plasma physics, plasma instabilities of various kinds play important roles. Some laboratory examples include instabilities limiting inertial or magnetic confinement of fusion plasmas, instabilities which produce enhanced radiation and anomalous transport coefficients in current-carrying plasmas, and instabilities which provide coherent sources of radiations in gyrotrons and free electron masers. Some examples from space plasmas include instabilities which produce nonthermal wave and particle distributions in the magnetosphere and the interplanetary medium and nonthermal radiation from the planets and the solar corona, instabilities involved in nonlinear propagation effects in the ionosphere, and instabilities leading to scattering and acceleration of fast particles in astrophysical plasmas. The richness and variety of the plasma instabilities and the diversity of their applications preclude any thorough treatment in a single book. In this book I have attempted to be thorough only in the coverage of the qualitative kinds of plasma instability which are possible. The main emphasis is on instabilities at moderate to high frequencies, that is frequencies from about the ion gyrofrequency to above all the natural frequencies.