Two-dimension plasma expansions with anisotropic pressure

TL;DR

This paper introduces a self-similar two-dimensional plasma expansion model with anisotropic pressure, revealing how the plasma front shape depends on temperature ratios and predicting high-energy emissions at specific angles.

Contribution

It presents a novel analytical solution for anisotropic plasma expansion, linking the shape of the plasma front to temperature ratios and experimental observations.

Findings

The plasma front can be hyperbolic, planar, or elliptical depending on parameters.

Experimental data supports the model for certain temperature ratios.

High-energy plasma emission occurs at near 90 degrees for specific conditions.

Abstract

A two-dimension self-similar solution is proposed for a plasma expansion with anisotropic pressure. With the solution, it depends on the relationship between the ratio of the longitudinal and the transverse temperature of the plasma, $\kappa^2$ and the electron-ion mass ratio, $\mu$, that the plasma front is composed by a part of hyperbolic (or a plane) and a small pointed projection at the center or a part of an ellipse. Zhang and coworkers's experiments (PRL, 99, 167602 (2007))support our results for $\kappa^2\in(\tau,1]$. For $\kappa^2\leq\tau$, there is an anomalous high-energy plasma emission at the angle of near $90^{\text{o}}$ due to longitudinal Coulomb explosion.