Relaxation Dynamics of Magnetized Plasma Bubbles Propagating into a Background Magnetized Plasma and the Emergence of Magneto-Rayleigh Taylor Instability

A magnetized coaxial gun launches a hot dense plasma bubble into a background magnetized plasma generated by a linear plasma device. The subsequent relaxation dynamics of this interaction is observed using a fast-framing camera and a visible spectrometer. To characterize the density, temperature, and magnetic field configuration of the plasma bubble, a triple Langmuir probe and B-dot magnetic probe array are also utilized. with the appropriate operating parameters, the bubble plasmas formed by the magnetized coaxial gun can exhibit spheromak-like equilibriums. The evolution of such spheromak-like plasma resembles the self-similar expansion observed in interplanetary magnetic clouds. However, when the bubble plasma is injected into the background magnetized plasma, it becomes deformed asymmetrically due to magnetic tension forces, leading to the growth of the Magneto-Rayleigh Taylor instability at one edge of the bubble. At the interface between the bubble and the background magnetized plasma the finger-like structures are observed. And the estimated growth rate of these “fingers” from the experimental data is consistent with the MRT instability.