Energy Loss of a Test Charge in Dusty Plasmas: Collective and Individual Particle Contributions

Abstract

The energy loss of a test charge in dusty plasma with dust charge fluctuations has been calculated both analytically (within the frame work of dielectric theory) as well as numerically. The dust charge relaxation rate is found to have a significant effect on the total energy loss of a test charge which is the sum of collective response of the plasma and individual particle interaction. It is shown that the dust charge fluctuation enhances the energy loss due to the collective response of the plasma as well as the individual particle contributions. Further, the charge fluctuation converts the static Coulomb potential to a potential well for slow charge relaxation rates and a small test charge velocity. The test charge therefore gains energy instead of loosing. On the other hand for the large test charge velocity and fast charge relaxation rate, a shielded Debye Hückel type potential is formed and consequently the energy loss is enhanced. These results are useful for understanding coagulation of dust grains in space and laboratory plasmas.