# Interpretation of quasi-periodic frequency sweeping in electron cyclotron emission of nonequilibrium mirror-confined plasma sustained by high-power microwaves

## TL;DR

This paper provides a rigorous analysis of chirping frequency patterns in electron cyclotron emission from nonequilibrium plasma, confirming the role of the 'holes and clumps' mechanism through Berk-Breizman theory.

## Contribution

It offers the first rigorous theoretical validation of the 'holes and clumps' mechanism explaining frequency chirping in high-frequency electron cyclotron emission.

## Key findings

- Confirmed the 'holes and clumps' mechanism as the cause of chirping patterns.
- Applied Berk-Breizman theory to mirror-confined plasma.
- Provided a quantitative framework for phase space structure formation.

## Abstract

In [Viktorov M. E. et al., Eur. Phys. Lett., V.116, P.55001, 2016] we reported on chirping frequency patterns that have been observed in the electron cyclotron emission from strongly nonequilibrium plasma confined in a table-top mirror magnetic trap. These patterns were interpreted qualitatively as the first experimental evidence for so-called "holes and clumps" mechanism acting at such high frequencies (1-10 GHz). In the present paper, we prove this statement on a more rigorous basis, considering the formation of nonlinear phase space structures in proximity of the wave-particle resonances within the framework of the Berk-Breizman theory adopted for a kinetically unstable mirror-confined plasma.