Evolution of the electron cyclotron drift instability in two-dimensions

TL;DR

This paper investigates the evolution of the Electron Cyclotron Drift Instability in two-dimensional plasmas using particle-in-cell simulations, revealing complex nonlinear interactions, wave breaking, and the development of the Modified Two-Stream Instability that causes electron heating.

Contribution

It provides new insights into the nonlinear evolution and spectral cascade of ECDI, including the identification of the MTSI mode and its effects in a 2D plasma setting.

Findings

Development of cyclotron harmonics and wave breaking.

Spectral cascade toward long wavelengths in density and current fluctuations.

Identification of the MTSI mode causing electron heating.

Abstract

The Electron Cyclotron Drift Instability (ECDI) driven by the electron $E\times B$ drift in partially magnetized plasmas is investigated with highly resolved particle-in-cell simulations. The emphasis is on two-dimensional effects involving the parallel dynamics along the magnetic field in a finite length plasma with dielectric walls. It is found that the instability develops as a sequence of growing cyclotron harmonics demonstrating wave breaking and complex nonlinear interactions, being particularly pronounced in ion density fluctuations at short wavelengths. At the same time, nonlinear evolution of fluctuations of the ion and electron density, as well as the anomalous electron current, shows cascade toward long wavelengths. Tendency to generate long wavelength components is most clearly observed in the spectra of the electron density and the anomalous current fluctuations. An intense but slowly growing mode with a distinct eigen-mode structure along the magnetic field develops at a later nonlinear stage enhancing the tendency toward long wavelength condensation. The latter mode having a finite wavelength along the magnetic field is identified as the Modified Two-Stream Instability (MTSI). It is shown that the MTSI mode results in strong parallel heating of electrons.