Interaction of driven "cold" electron plasma wave with thermal bulk mediated by spatial ion inhomogeneity

TL;DR

This study uses high-resolution simulations to explore how driven cold electron plasma waves interact with thermal bulk in inhomogeneous ion backgrounds, revealing mode coupling, phase space structures, and effects of ion inhomogeneity.

Contribution

It demonstrates the dynamics of driven cold electron plasma waves in inhomogeneous plasmas, highlighting mode coupling, energy transfer, and the influence of ion inhomogeneity on wave behavior.

Findings

Mode coupling between EPW and sidebands is illustrated.

Formation of BGK-like phase space structures is observed.

Ion inhomogeneity affects energy transfer and wave dynamics.

Abstract

Using high resolution Vlasov - Poisson simulations, evolution of driven ``cold" electron plasma wave (EPW) in the presence of stationary inhomogeneous background of ions is studied. Mode coupling dynamics between ``cold'' EPW with phase velocity $v_{\phi}$ greater than thermal velocity i.e $v_{\phi} \gg v_{thermal}$ and its inhomogeneity induced sidebands is illustrated as an initial value problem. In driven cases, formation of BGK like phase space structures corresponding to sideband modes due to energy exchange from primary mode to bulk particles via wave-wave and wave-particle interactions leading to particle trapping is demonstrated for inhomogeneous plasma. Qualitative comparison studies between initial value perturbation and driven problem is presented, which examines the relative difference in energy transfer time between the interacting modes. Effect of variation in background ion inhomogeneity amplitude as well as ion inhomogeneity scale length on the driven EPWs is reported.