Experimental investigation of coaxial-gun-formed plasmas injected into a background transverse magnetic field or plasma

TL;DR

This study experimentally investigates how coaxial-gun-formed plasmas behave when injected into background magnetic fields or plasmas, revealing phenomena like kink stabilization and magneto-Rayleigh-Taylor instabilities in a linear plasma device.

Contribution

It provides new experimental insights into plasma injection dynamics and instability behaviors in magnetized environments, expanding understanding of plasma stability and structure formation.

Findings

Kink stabilization occurs due to sheared flow formation.

Finger-like structures indicate magneto-Rayleigh-Taylor instability.

Similar behaviors observed in jets and spheromaks in low-beta plasmas.

Abstract

Injection of coaxial-gun-formed magnetized plasmas into a background transverse vacuum magnetic field or into a background magnetized plasma has been studied in the helicon-cathode (HelCat) linear plasma device at the University of New Mexico [M. Gilmore et al., J. Plasma Phys.81, 345810104 (2015)]. Magnetized plasma jet launched into a background transverse magnetic field shows emergent kink stabilization of the jet due to the formation of a sheared flow in the jet above the kink-stabilization threshold $0.1kV_A$ [Y. Zhang et al., Phys. Plasmas 24, 110702 (2017)]. Injection of a spheromak-like plasma into a transverse background magnetic field led to the observation of finger-like structures on the side with a stronger magnetic field null between the spheromak and background field. The finger-like structures are consistent with magneto-Rayleigh-Taylor instability. Jets or spheromaks launched into a background, low-$\beta$ magnetized plasma show similar behavior as above, respectively, in both cases.