Characterization of fast magnetosonic waves driven by compact toroid plasma injection along a magnetic field

TL;DR

This study observes and characterizes fast magnetosonic waves generated by compact toroid plasma injections in a magnetic field, providing insights relevant for magneto-inertial fusion research.

Contribution

It experimentally identifies fast magnetosonic waves driven by CT plasma injection and analyzes how background magnetic conditions influence these waves.

Findings

Waves are identified as fast magnetosonic modes propagating perpendicular to the magnetic field.

Background magnetic field and flux influence wave characteristics.

Results support future development of tangled magnetic field targets for fusion.

Abstract

Magnetosonic waves are low-frequency, linearly polarized magnetohydrodynamic (MHD) waves commonly found in space, responsible for many well-known features, such as heating of the solar corona. In this work, we report observations of interesting wave signatures driven by injecting compact toroid (CT) plasmas into a static Helmholtz magnetic field at the Big Red Ball (BRB) Facility at Wisconsin Plasma Physics Laboratory (WiPPL). By comparing the experimental results with the MHD theory, we identify that these waves are the fast magnetosonic modes propagating perpendicular to the background magnetic field. Additionally, we further investigate how the background field, preapplied poloidal magnetic flux in the CT injector, and the coarse grid placed in the chamber affect the characteristics of the waves. Since this experiment is part of an ongoing effort of creating a target plasma with tangled magnetic fields as a novel fusion fuel for magneto-inertial fusion (MIF), our current results could shed light on future possible paths of forming such a target for MIF.