| Dusty Plasma |
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Dusty plasmas are encountered in:
Dusty plasmas are interesting because presence of particles significantly alters the charged particle equilibrium leading to different phenomena. It is field of current research. CHARACTERISTICS The temperature of dust in a plasma may be quite different from its environoment. For example:
The ''', which tends to reduce the negative potential, can be important due to the small size of the particles. The Photoelectric Effect and the impact of positive ions may actually result in a positive potential of the dust particles. DYNAMICS The motion of solid particles in a plasma follows the ''momentum equation'' for ions and electrons: where m, q are the mass and charge of the particle, g is the gravitation acceleration, m''v''c'''v''' is due to viscosity, and '''f''' respresents all other forces including radiation pressure. Then depending in the size of the particle, there are four categories: #Very small particles, where q ('''E''' + '''v''' × '''B''') dominates over m'''g'''. #Small grains, where q/m ≈ √G, and plasma still plays a major role in the dynamics. #Large grains, where the electromagnetic term is negligible, and the particles are referred to as grains. Their motion is determined by gravity and viscosity, and the equation of motion becomes m''v''c'''v''' = m'''g'''. #Large solid bodies. In centimeter and meter-sized bodies, viscosity may cause significant perturbations that can change an orbit. In kilometer-sized (or more) bodies, gravity and inertia dominate the motion. REFERENCES
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