Abstract
Dust grains can be charged to a positive surface potential by various processes. Grains of irregular shapes can reach high surface field even with moderate potential and the electric field initiated self-discharging of such charged grains can be of a high importance for determination of its equilibrium charge.
We have measured the self-discharging current from single positively charged glassy carbon dust grains trapped in the electrodynamic quadrupole under various conditions. The surface electric field was in the range from 1 to 4 kV/μm.
Measured increase of the current after implanting Ar ions into the grain indicates that the ionization probability of atoms leaving the grain surface is six orders of magnitude higher compared to the ionization of same atoms of surrounding gas.