Three-dimensional instability of two nonlinearly coupled electromagnetic waves in a plasma

TL;DR

This paper investigates the three-dimensional instability of two coupled electromagnetic waves in unmagnetized plasma, revealing enhanced instability in two-plasmon decay and additional instability regions in ion parametric decay, with implications for laser-plasma and ionospheric heating.

Contribution

It provides a theoretical and numerical analysis of coupled wave instabilities in plasma, highlighting new instability behaviors in specific decay regimes.

Findings

Enhanced instability in two-plasmon decay regime.

Additional instability regions in ion parametric decay.

Relevance to laser-plasma and ionospheric heating experiments.

Abstract

The three-dimensional instability of two coupled electromagnetic waves in an unmagnetized plasma is investigated theoretically and numerically. In the regime of two-plasmon decay, where one pump wave frequency is approximately twice the electron plasma frequency, we find that the coupled pump waves give rise to enhanced instability with wave vectors between those of the two beams. In the case of ion parametric decay instability, where the pump wave decays into one Langmuir wave and one ion acoustic wave, the instability regions are added with no distinct amplification. Our investigation can be useful in interpreting laser-plasma as well as ionospheric heating experiments.