Dust Particles And Low Pressure Plasma Interaction

Charged dust particles exist widely in space, laboratory as well as plasma processing. The interactions between dust particles and plasmas have attracted much attention in the recent years since dust contamination is recognized as a serious problem in plasma processing of integrated circuits. In this paper, we focus on the following three topics:(I) Density distribution of dusty plasma in the low-pressure collisionless positive columnThe radial density distributions of electron, ion and dust particle in the low-pressure collisionless positive column are investigated with a fluid theory and a self-consistent dust-charging model. Numerical simulation results indicate that, for low temperature dust particles, dust particles mainly exist in the area near the column center and their charge-number can be considered as a constant, while in the area where there are no dust particles, ion and electrons are in ambipolar diffusion; for high temperature dust particles, both the distribution regions of dust particle and high ion density are expanded and dust charge-number is increasing with the distance from the center.(II) Charging effects on temporal and spatial evolution of dusty plasma sheath in plasma source ion implantation.The temporal and spatial evolution of a dusty plasma sheath in plasma source ion implantation has been investigated with a fluid theory and a self-consistent dust-charging model. A negative potential pulse is introduced to form the plasma sheath. The effect of the dust charging process becomes significant when the charging time is longer than either the pulse period or the ion response time (measured by the inverse of the ion plasma frequency). Numerical results indicate that the sheath expands faster than dust-free sheathes. It is also shown that, for small dust particles, the motion of dust particles is very remarkable and the charging effect can be negligible, and for large dust particles, the charging effect of dust particles becomes more evident while they are almost kept stationary during the whole negative potential pulse.(III) Dust charging and levitation in cathode sheath of glow discharges with energetic electron beam. The dust charging and levitation in a collisionless cathode sheath of dc glow discharges withenergetic electron beams released from a plane cathode are investigated with a self-consistent theoretic model. The dust charging associated with the electron beams including the secondary emission of dust can dominate the dust surface potential in the close cathode region. In this case, dust of the same size can levitate at two different positions in the cathode.