Doctor of Physicomathematical Sciences. Prior to 1956 his scientific interests centered on quantum electrodynamics. From 1957 to 1960 he elaborated the theory proposed by Wexler for coherent methods of charged particle acceleration. Since 1959 he has studied plasma physics and astrophysics. Tsytovich has been responsible, in particular, for investigations of the properties of relativistic plasma, the physics of turbulent plasma, and nonlinear effects in plasma.The original Russian text, first published by Nauka Press in Moscow in 1967, has been corrected by the author for this edition. The present translation is published under an agreement with Mezhdunarodnaya Kniga, the Soviet book export agency.

Dusty plasmas in a gas discharge often feature a stable void, i.e., a dust-free region inside the dust cloud. This occurs under conditions relevant to both plasma processing discharges and plasma crystal experiments. The void results from a balance of the electrostatic and ion drag forces on a dust particle. The ion drag force is driven by a flow of ions outward from an ionization source and toward the surrounding dust cloud, which has a negative space charge. In equilibrium the force balance for dust particles requires that the boundary with the dust cloud be sharp, provided that the particles are cold and monodispersive. Numerical solutions of the one-dimensional nonlinear fluid equations are carried out including dust charging and dust-neutral collisions, but not ion-neutral collisions. The regions of parameter space that allow stable void equilibria are identified. There is a minimum ionization rate that can sustain a void. Spatial profiles of plasma parameters in the void are reported. In the absence of ion-neutral collisions, the ion flow enters the dust cloud's edge at Mach number M=1. Phase diagrams for expanding or contracting voids reveal a stationary point corresponding to a single stable equilibrium void size, provided the ionization rate is constant. Large voids contract and small voids expand until they attain this stationary void size. On the other hand, if the ionization rate is not constant, the void size can oscillate. Results are compared to recent laboratory and microgravity experiments.

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Doctor of Physicomathematical Sciences. Prior to 1956 his scientific interests centered on quantum electrodynamics. From 1957 to 1960 he elaborated the theory proposed by Wexler for coherent methods of charged particle acceleration. Since 1959 he has studied plasma physics and astrophysics. Tsytovich has been responsible, in particular, for investigations of the properties of relativistic plasma, the physics of turbulent plasma, and nonlinear effects in plasma.The original Russian text, first published by Nauka Press in Moscow in 1967, has been corrected by the author for this edition. The present translation is published under an agreement with Mezhdunarodnaya Kniga, the Soviet book export agency.