Numerical investigation of fine-particle gyrophase drift

Summary form only given. The gyration of a dust grain due to the Lorentz force depends on the grain charge among other parameters. Gyrophase-resonant excursions into inhomogeneous regions causing periodic charge-state changes may occur in science and industry dusty-plasma laboratory experiments involving a strong magnetic field and either inhomogeneous UV illumination or inhomogenous plasma potential. A phase lag between the grain charging cycle and the cycle associated with the grain´s instantaneous surface potential or photocurrent results in a modification to the usual ExB drift, and is known as gyrophase drift [1,2]. The motion of a single dust grain is computed numerically for three different charging models (Orbit-Motion-Limited, Collision-enhanced-current, and Hydrodynamic) while the grain executes its gyro-orbit in inhomogeneous plasma. Parameters are varied, including the ratio of charging timescale to the grain gyroperiod, inhomogeneity length scale to the grain gyroradius, and characteristic axis of the inhomogeneity with respect to the magnetic field direction. The sensitivity of the gyrophase drift upon this model choice will be evaluated by determining the magnitude of the gyrophase drift for parameters relevant to selected astrophysical and experimental regimes. One goal of this project is to emphasize the utility of the charging-model sensitivity of gyrophase drift phenomenon, specifically in a future magnetized-orbit dusty plasma experiment being constructed at Auburn University, to experimentally validate charging-model details for space plasma physics and industrial applications.