A 3D Magnetohydrodynamic simulation for the propagation of plasma plume transverse to applied magnetic field

TL;DR

This paper uses 3D ideal-MHD simulations to explore how laser-generated plasma plumes expand in a transverse magnetic field, revealing magnetic field line deformation, cavity formation, and collapse phenomena.

Contribution

It demonstrates that ideal MHD effectively models plasma plume expansion in moderate magnetic fields, aligning simulation results with recent experimental observations.

Findings

Magnetic field lines are pushed outward and bent by the plasma plume.

A cavity forms in the plasma core due to magnetic and plasma pressure interactions.

The cavity collapses as plasma pressure drops, consistent with experimental data.

Abstract

We have carried out a 3D ideal-MHD (Magnetohydrodynamic) simulation to study the evolution of laser generated plasma plume in a moderate external magnetic field (0.13 T) oriented perpendicular to the flow direction of the plasma plume. The simulation shows that the plasma plume pushes the external magnetic field lines outward in the direction of the expansion. This leads to compression and bending of the magnetic field lines.The force resulting from the change in shape and the density of magnetic field lines opposes the expansion of the plume. An elliptic layer of shocked plasma is formed at the plasma/external field interface leaving a cavity in the plume core due to the outward expansion and the inertia of the plume. As the plasma pressure drops due to expansion, the imbalance between the magnetic energy and the internal energy results in the collapse of the cavity. These observations have striking similarities with the observations of the experiments [Phys. Plasmas 24, 033511 (2017)] performed recently to study the plasma plume expansion in the presence of an external transverse magnetic field. This similarity indicates that the physical mechanisms dominantly governing the plasma plume expansion in the moderate magnetic field are aptly described in the ideal MHD regime. The studies thus show that the laser generated plasma plume can be utilized to carry out interesting experiments on MHD phenomena in a simple laboratory set up.