Charging of spinning insulating ob jects by plasma and photoemission

Abstract

The charging of spinning insulating objects by plasma and photoemission is studied with the particle-in-cell method. Unidirectional photon flux, different angular velocities of the object, and different plasma flow speeds are considered. Photoemission can lead to a positive total charge and electric dipole moment on the object. The spinning of the object redistributes the surface charge. The total object charge oscillates in time with the period matching the period of the object rotation. Plasma potential and density in the vicinity of the object oscillate with the same frequency. The plasma is rarefied close to a positively charged object, and the density wake diminishes when the object is charged negatively. The time averaged charge depends on the angular velocity of the object.Comment: 15 pages, 4 figures, submitted to Geophys. Res. Let