Critical effects in screening of high-Z impurities in plasmas

The screening of a highly charged grain immersed in a plasma background was investigated by means of the microscopic Monte Carlo simulations and withi n the Poisson-Boltzmann theory allowing for nonlinear effects. It was shown that a strong plasma-grain coupling causes, in a distinct contrast to the linear Debye-Huckel screening theory, the accumulation of the induced plasm a charge on the grain surface, accompanied by a sharp reduce in the effecti ve charge. (C) 1999 Elsevier Science B.V. All rights reserved.