Study of the Charging of Dust Grains in Space Plasma

The charging of dust grains in nonequilibrium space plasma in the orbit motion limited (OML) approximation is studied taking into account various mechanisms for a wide range of parameters of space plasma. Expressions are obtained for the ion and electron fluxes under conditions of a non-Maxwellian distribution of plasma particles. It is shown that, at low grain energies, these formulas are transformed into expressions derived from the Maxwellian distribution. Under the condition of the balance of ion and electron fluxes on the surface of dust grains, dependences of the reduced charge on the electron and ion temperature and mass ratios are obtained. The dependence of the reduced charge on the charging time is also obtained. The characteristic charging time of dust grains in the case of a nonequilibrium kappa distribution increases compared to that for the Maxwellian distribution.