Kinetic simulation on ion acoustic wave in gas discharge plasma with convective scheme

In a one-dimensional plasma-sheath system representing a concave quasistati onary electric potential typical of a negatively charged system, oscillatio ns of ion are simulated by the aid of a convective scheme useful for weakly ionized plasma, and are theoretically investigated. The frequency spectra of the ion current through a cathode reveal to us that two modes of ion aco ustic waves are dominant; a high and a low frequency mode. By deriving a li near differential equation with a dissipation and an ion flow, and taking f or granted the sheath width and the distribution of ion flow velocity, the dispersion relation for a finite length system can be calculated. The simul ation results, such as the reinforcement of the low frequency mode and the suppression of the high frequency mode, are satisfactorily corroborated by the linear theory. The instabilities of the waves are caused by the asymmet ry of boundary conditions and by the dissipative effect. (C) 2000 American Institute of Physics. [S1070-664X(00)00603-0].