CHARGING PROCESS OF SPACE DUST AND ITS DEPENDENCE UPON PLASMA PARAMETERS

Dust grains immersed in plasma will be charged of various charging currents, this paper considers three main currents due to the relative velocity between the dust grains and the plasma: the primary ions, the primary electrons, and the sec-ondary electrons. The surface potentials of silicate and carbon dusts grains in H⁺ and H₂O⁺ plasma environments are calculated using universal plasma parameters, these plasma conditions are common in space environments, such as comets, plan-etary rings, and interplanetary media. A conclusion is found that the equilibrium potential of dust grains have close correlation with the plasma temperature. At low temperatures, the surface potential will become lower while the temperature rises. The dust can reach a positive potential when the temperature is high enough. The potential of carbon grains is lower than that of silicate grains. The component of plasma may affect the potential, too. For both silicate and carbon grains, potential in H+ plasma is higher than that in H₂O⁺ plasma.