CHARGING OF DUST GRAINS IN A PLASMA

Charging of micron-sized dust grains in a plasma has been investigated experimentally. Dust grains were dispersed into a fury ionized, stead y-state, magnetized plasma column consisting of electrons and K+ ions, both at a temperature of approximate to 0.2 eV. Langmuir probe measur ements were used to determine how the negative charge in the plasma is divided between free electrons and dust grains. By varying the ratio d/lambda(D) between the intergrain spacing and the plasma Debye length , the predicted reduction in the grain charge for the case of ''closel y packed'' grains (d/lambda(D), < 1) has been demonstrated experimenta lly.