Modulation Of Void Motion Behavior Of Dusty Plasma Under Electromagnetic Field

Dusty plasmas are fully or partially ionized low-temperature gases comprisingneutral gas molecules, electrons, ions, and submicron-and micron-sized charged dustgrains. Dust and dusty plasmas are ubiquitous in space, and have a great influence onthe plasmas in space and laboratory, as well as in fusion and semiconductor processing.The massive and charged dusts has a great influence on the dusty plasma, and isresponsible for a rich variety of phenomena occurring in the systems, including dustvoids, mach cones, dusty plasma crystal, dust lattice waves and dust rotation under amagnetic field, etc. These static and dynamical motion properties of the dusts are oftendetermined by the ion drag force on the dusts.In this paper, we proposed a nonlinear time-dependent model for void formation industy plasmas. In cylindrical coordinate, we modulated the void motion behavior in astatic electric or magnetic field and an alternating magnetic field.First, we proposed atime-dependent model for void formation in dusty plasmas in Cartesian coordinate andconformed that the voids are formed by the interaction of ion drag force and electricforce on the dusts. In cylindrical coordinate we also found the dust void grows with theneutral gas pressure, which is consistent with the experimental observations.In staticelectric field, we studied the impact of the static electric field on the size of the void andfound the electric force changes the balance position of the dusts.Then we proposed amodel for void formation and the rotation of the dusts in a static magnetic field. In theradial direction, the inward electrical force and the outward ion drag force on negativelycharged dust particles make the initial uniform equilibrium dust density evolve to a void,without obvious effect of the static magnetic field. In the tangential direction, theazimuthal component of the ion drag force pushes the dusts rotating around the axis ofthe magnetic field, which means the rotation of the dusts is caused by the drag of theazimuthal ion flow. Meanwhile, the azimuthal velocities of ion and dust are bothproportional to the strength of the magnetic field and the rotation of dusts slows downwith the increase of neutral gas pressure, which are consistent with the phenomenaobserved in experiments. Besides, when we take account of both static electric andmagnetic field, the results of them turn out to be independent.Finally, we furtherdeveloped the model to study the void motion behavior in an alternating magnetic field.The vortex electric field caused by the alternating magnetic field disturbs the azimuthalion flow and has an impact on the rotation of dusts, which ultimately extends the voids.In conclusion, the electromagnetic field can modulates the void motion behavior,and a different field has a unique effect. These results can be used in the study of dustyplasmas in different areas.