Charged double layer at the boundary between a symmetric plasma and a wall

Abstract

It is shown that the features of formation and structure of a stationary charged layer at the interface between a symmetric plasma and a wall depend to a considerable extent on the ratios τ± (for both plasma components) of the thermal velocity to the velocity of the plasma flow at the beginning of the layer, as well as on the polarity and magnitude of electric potential φW of the wall. The conditions under which a double layer-type structure can be formed in the near-wall layer of the symmetric plasma are formulated. The charge double layer contains two sublayers with opposite polarities of charge for a fixed polarity of the wall. The charge polarity of sublayer adjoining the plasma is opposite to the polarity of the wall, while the sublayer adjoining the wall has a charge of the same polarity as that of the wall. The ranges of symmetric plasma parameters for which the double layer exists are determined. It is found that a structure of this type can be formed nor for all parameters of the plasma, for which a charged layer exists; the possibility of formation of this structure depends on τ± as well as on the sign of the potential of the wall.