In the interest of speed and economy the notation of the original text has been retained so that the cross product of two vectors A and B is denoted by [AB], the dot product by (AB), the Laplacian operator by ~. etc. It might also be worth pointing out that the temperature is frequently expressed in energy units in the Soviet literature so that the Boltzmann constant will be missing in various familiar expressions. In matters of terminology, whenever possible several forms are used when a term is first introduced, e. g. , magnetoacoustic and magnetosonic waves, "probkotron" and mirror machine, etc. It is hoped in this way to help the reader to relate the terms used here with those in existing translations and with the conventional nomenclature. In general the system of literature citation used in the bibliographies follows that of the American Institute of Physics "Soviet Physics" series. Except for the cor­ rection of some obvious misprints the text is that of the original. We wish to express our gratitude to Academician Leontovich for kindly providing the latest corrections and additions to the Russian text. v CONTENTS Steady-State Plasma Flow in a Magnetic Field A. I. Morozov and L. S. Solov'ev Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Chapter 1. Acceleration Mechanisms , • • • • • • • • • • . 2 §1. Microscopic Picture of Plasma Acceleration . . . . . . . . . . . . . . . . . . . 2 §2.