Numerical Studies on the Non-Equilibrium Transport of Charged Particles in a Confined Decaying Plasma: Effects of the Ion Rarefaction Waves

Abstract

For a decaying plasma confined between two biased electrodes, previous studies mainly focused on the dynamics of the transient Child-Langmuir sheath. Our recent studies showed that, except for the sheath contributions, the propagations of the ion rarefaction waves during the plasma decaying process also play a significant role in determining the non-equilibrium transport processes of the charged particles[1][2][3] In this study, the influences of the initial key plasma parameters and the external energetic beams on the dynamic behaviors of the charged particles are analyzed and simulated based on the particle-in-cell (PIC) method. On the one hand, the influences of the ion rarefaction waves excited by the initial electron oscillations on the ambipolar component of the total ion flux are analyzed. This reveals the coupling of the initial electron temperature and plasma density on the transport of the charged particles[1],[2]. On the other hand, the externally injected electron beam interacts with the bulk plasmas, which enables the growth of a Langmuir standing wave. This would heat the bulk electrons, and lead to the increase of the ion flux to the electrodes[3].