The parametric instability in the inductively coupled plasma driven by the ponderomotive current

TL;DR

This paper develops a stability theory for skin layer plasma in inductive discharges, revealing a parametric instability driven by ponderomotive currents when electron quiver velocities are high, with implications for plasma behavior.

Contribution

It introduces a new theoretical framework for analyzing parametric instability in skin layer plasma under high electron quiver velocities, considering oscillating electron motions.

Findings

Predicts parametric instability with growth rate comparable to RF frequency.

Identifies the instability's dependence on ponderomotive current velocity.

Shows the instability occurs only in finite, inhomogeneous plasma regions.

Abstract

The stability theory of the skin layer plasma of the inductive discharge is developed for the case when the electron quiver velocity in RF wave is of the order of or is larger than the electron thermal velocity. This theory is grounded on the methodology of the oscillating modes, which accounts for the oscillation motion of the electron component relative to the unmovable ions in the spatially inhomogeneous RF field of the skin layer. The theory predicts the existence the instability of the parametric type in a skin layer with the growth rate comparable with frequency. This instability stems from the coupled action of two effects caused by the electron-ion relative motion in RF field: occurrence of harmonics of the perturbed potential and their coupling due to the ponderomotive current. The instability exists in the finite interval of the ponderomotive current velocity and is absent in the uniform boundless plasma.