Kinetic Simulation of an Ion Acoustic Wave with Charge Exchange Process in Direct Current Discharge Plasma

A charge exchange model is set and its simulation results are compared to those of previous friction model in the lower current branch of a discharge plasma. A remarkable delocalization of a high frequency mode is found in the charge exchange model. When the mean free path of the charge exchange is larger than the system size, the effective temperature is lower than that of the friction model. However, with a decrease of the mean free path, the temperatures of the two models are inverted. Although the bifurcations of the fundamental mode described in previous paper are similarly reproduced, a parameter range has shifted and it is difficult to observe the ponderomotive effect in the charge exchange model. Simulation results are discussed from the view point of the second moments of the distribution function in both velocity and coordinate spaces. It is found that the effects due to the ponderomotive force and previously pointed-out sheath condition are concealed under the diffusion defined by the second moment of the displacement of scattered particles.