Charging times for dust particles in plasma

The carging time for grains of micron sizes is studied theoretically with some selected parameters to match the environment of space plasmas. Two models are considered: when the grain is isolated, and when the grain density increases so that the spherical capacitor model and consequently the intersection of the grain Debye spheres is applied. The analysis shows that for both models, the charging time is a strong function of plasma electron temperature. The proximity of the neighbouring grains has effect on both the grain capacitance and the potential difference due to the depletion of the electron population in the plasma. There is one value for the characteristic as well as there is an inversion point at a certain value of the charge on the grain. 4 figs., 9 refs