Beyond the Oberbeck-Boussinesq and long wavelength approximation

TL;DR

This paper introduces advanced simulations of magnetized plasma that include non-Oberbeck-Boussinesq effects and arbitrary wavelength polarization, revealing their significant impact on plasma blob dynamics and providing generalized scaling laws.

Contribution

First simulation incorporating both effects in a reduced plasma model, showing their influence on plasma behavior and deriving unified scaling laws.

Findings

Gyro-amplification enhances small-scale vorticity fluctuations.

Non-Oberbeck-Boussinesq effects reduce blob growth rate and linear acceleration.

Unified scaling laws include ion temperature and amplitude dependence.

Abstract

We present the first simulations of a reduced magnetized plasma model that incorporates both arbitrary wavelength polarization and non-Oberbeck-Boussinesq effects. Significant influence of these two effects on the density, electric potential and ExB vorticity and non-linear dynamics of interchange blobs are reported. Arbitrary wavelength polarization implicates so-called gyro-amplification that compared to a long wavelength approximation leads to highly amplified small-scale ExB vorticity fluctuations. These strongly increase the coherence and lifetime of blobs and alter the motion of the blobs through a slower blob-disintegration. Non-Oberbeck-Boussinesq effects incorporate plasma inertia, which substantially decreases the growth rate and linear acceleration of high amplitude blobs, while the maximum blob velocity is not affected. Finally, we generalize and numerically verify unified scaling laws for blob velocity, acceleration and growth rate that include both ion temperature and arbitrary blob amplitude dependence.