Electrostatic potential behind a macroparticle in a drifting collisional plasma: Effect of plasma absorption

The electric field and potential behind a small absorbing body (dust grain) at floating potential has been calculated analytically in a highly collisional drifting plasma. Linear plasma response formalism has been used and main attention has been focused on the effect of plasma absorption on the grain. It is shown that the long-range asymptote of the electric field is dominated by the effect of absorption and is always negative. Depending on plasma parameters, the electric field at intermediate distances can either increase monotonically or exhibit one maximum and one minimum. It can achieve positive values in certain parameter regimes, which indicates the possibility of electrostatic attraction between the grains aligned parallel to the flow. The obtained results can be important for understanding of the binary grain interactions in complex plasmas at elevated pressures.