WAKE POTENTIAL OF A DUST GRAIN IN A PLASMA WITH ION FLOW

Debye screening potential and wake potential for a moving dust grain i n a collisionless plasma with ion flow is studied. When a relative vel ocity of the dust grain exceeds the ion acoustic velocity, the oscilla tory wake potential is formed in a circular cone behind the particle a nd produces potential minima in a periodic manner. The ion acoustic co llective effects on dust particles contribute to the formation of the periodic structure. The characteristic spacing between the potential m inima are several times of Debye wavelength in height and in radius. S uch a periodic structure may be relevant to the formation of Coulomb q uasilattices (plasma crystals) observed in the dusty plasma laboratory experiments. (C) 1997 American Institute of Physics.