Investigation of spatiotemporal behavior of the plasma density during the development of the thermocurrent instability

Abstract

Considering a weakly ionized, collisional, quasineutral plasma placed in an electric field under the condition of nonresonant Cerenkov radiation and using the hydrodynamic model, a nonlinear diffusionlike equation with negative diffusion coefficient is obtained, which describes the dynamics of plasma density during the development of the thermocurrent instability. This equation is solved by the Adomian decomposition method. According to this solution, the spatiotemporal behavior of the plasma density during the growth of the thermocurrent instability is investigated. It is shown that the development of the thermocurrent instability causes the initial perturbations in the plasma density to grow. Also, it is shown that the increment in these perturbations continues until the growth of the thermocurrent instability ceases due to the breakdown of the quasineutrality condition. In this case, it is seen that the profile of the plasma density does not change any more and gets to a constant limit.