# Parametric decay of plasma waves near the upper-hybrid resonance

## TL;DR

This paper develops a modified theory for the parametric decay instability of intense X waves near the upper-hybrid resonance, extending to high intensities where the growth rate saturates, and validates it with particle-in-cell simulations.

## Contribution

It introduces a new theoretical model for high-intensity regimes of plasma wave decay, providing explicit formulas for the instability rate.

## Key findings

- Derived an explicit formula for the instability growth rate at high intensities.
- Theoretical predictions align reasonably with particle-in-cell simulation results.
- Extended the understanding of plasma wave decay near the upper-hybrid resonance.

## Abstract

An intense X wave propagating perpendicularly to dc magnetic field is unstable with respect to a parametric decay into an electron Bernstein wave and a lower-hybrid wave. A modified theory of this effect is proposed that extends to the high-intensity regime, where the instability rate $\gamma$ ceases to be a linear function of the incident-wave amplitude. An explicit formula for $\gamma$ is derived and expressed in terms of cold-plasma parameters. Theory predictions are in reasonable agreement with the results of the particle-in-cell simulations presented in a separate publication.