Ion heating, burnout of the HF field and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

TL;DR

This paper investigates the development of parametric instabilities in intense Langmuir waves within plasma, analyzing energy transfer, ion sound generation, and effects of damping rate changes using hybrid models.

Contribution

It compares two hybrid models (Zakharov's and Silin's) for plasma wave instabilities, highlighting differences in energy transfer and spectral broadening.

Findings

Energy transfer to ions is more efficient at higher wave energies.

Reduced HF field damping delays burnout and broadens the spectrum.

Ion velocity distribution tends toward normal distribution under instability.

Abstract

The development of one-dimensional parametric instabilities of intense long-wave plasma waves is considered in terms of the so-called hybrid models, when electrons are treated as a fluid and ions are regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model -- ZHM) or greater (Silin's hybrid model -- SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency (LF) oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. Reduced absorption of the HF field leads to the retardation of the HF field burnout within plasma density cavities and to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.