1. if a positive (or negative) charge is inserted into a plasma, it will change the local charge distribution by attracting (repelling) electrons. The net result is an additional negative (positive) charge density which cancels the effect of the initial charge at distances large compared to the Debye length. (There is a corresponding effect of shielding by the ions, which, for various and subtle reasons, usually is less important.)
(13 Nov 1997)
Debye Shielding Pictures
Click any thumbnail below to go to the full-sized version of that picture or photo: