Theory of dust voids in plasmas.

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