Dynamical properties of random charge fluctuations in a dusty plasma with different charging mechanisms

A dust particle in a plasma acquires electric charge by collecting electron s and ions, and sometimes by emitting electrons. The charging currents cons ist of discrete charges, causing the charge to fluctuate around an equilibr ium value. We developed a model yielding a general expression for the charg e fluctuations' temporal autocorrelation function. Both the magnitude and c haracteristic time of fluctuations can be obtained, knowing the specific fo rm of charging currents. Numerical results are presented for different char ging mechanisms, including charging by thermionic and photoelectric emissio n. It is shown that for all charging mechanisms the amplitude of fluctuatio ns varies as Delta Z=alpha root[\Z\], where [Z] is the equilibrium dust;gra in charge in units of electron charges. [S1063-651X(99)09004-2].