Numerical investigation of sheath characteristics for electronegative magnetized plasma and dust charging

Abstract

We have studied the effects of the magnetic field on the active electronegative plasma sheath properties and dust charging process in the sheath region for two different collisional models: constant ion mean free path and constant ion mobility using 1d3v fluid hydrodynamics model. It is found that the magnetic field strength and choice of collisional models have a significant effect on the active plasma sheath characteristics and charging of an isolated dust grain. The sheath criterion for an active electronegative magnetized plasma for both collisional models has been extended, and the effects of neutral gas pressure, source frequency, obliqueness of magnetic field, and initial electric field at sheath edge are graphically illustrated. There are two distinct regions observed in the sheath region: magnetic field and electric field dominant regions. The spatial distribution of plasma sheath parameters is systematically presented. It is found that the evolution of dust surface potential is affected by the magnitude of the magnetic field and collisional models. The stable levitation of dust grains in the sheath region is close to the sheath entrance. Moreover, the total force experienced by an isolated dust grain in the sheath region rapidly increases close to the material surface, and the magnitude of force is higher for larger dust grain.

Effects of trapped electrons on the sheath at the boundary of a dusty plasma

“…12) The presence of highly charged dust grains causes a series of impacts both in the sheath structure and the sheath formation. [13][14][15][16][17][18] For example, Ma and Yu 13) demonstrated that dust can narrow the sheath to a few Debye lengths, and that the varying charge of dust plays a vital role in the progress of sheath formation. It was worth noting that, the experimental, 14) simulation 15) and numerical 18) works confirmed the conclusion that variably-charged dust can substantially affect the nature of the dusty plasma sheath.…”

“…It was worth noting that, the experimental, 14) simulation 15) and numerical 18) works confirmed the conclusion that variably-charged dust can substantially affect the nature of the dusty plasma sheath. Besides, assuming dust is constant-charged, Zhao et al 16) researched the properties of the sheath, taking the size distribution of dust into account. Considering polarization and charge gradient forces acting on the dust grains, He et al 17) studied the sheath formation and revealed that the influence of the forces on the critical Mach number.…”