SIMULATION OF DUSTY PLASMAS NEAR SURFACES IN-SPACE

A two-dimensional particle-in-cell/Monte Carlo simulation code is deve loped and used to examine the electrodynamics of a finite-size dust (p articulate) plasma. The model that can be applied to a dusty plasma bo unded by surfaces or to a dust cloud embedded in an unbounded plasma a ccounts for the dynamics of plasma and dust particles, includes the co llisional absorption of plasma species by the dust with the use of a m ultistep Monte Carlo algorithm, and solves Poisson's equation for the electric fields. Charging of isolated particulates is compared with es timates based on orbital motion-limited current collection. The charge and potential structure of finite-length dust clouds embedded in a pl asma are examined, and the results are compared to previous one-dimens ional solutions. The average dust charge is found to decrease with inc reasing dust density. Low-density dust clouds do not perturb the poten tial and their average charge approaches that of isolated particulates . In the case of dense dust clouds the potential forms a sheathlike st ructure while the charge forms a double layer with the negative charge residing on the outer boundary of the cloud. Dust clouds initialized in the sheath of a surface biased to a potential are also examined. It is found that the dusty plasma electrodynamics is affected by the app lied surface potential, plasma drift energy, and dust density. Collect ive effects in high-density clouds alter the sheath, which can expand or collapse. It is found that particulates can be charged negatively o r positively depending on the drift energy and the applied surface pot ential.