Experimental Study of Plasma Bubble Expansion and Instability growth in a magnetized background environment.

The expansion of magnetized plasma bubbles into an external magnetic field is a fundamental process relevant to astrophysical phenomena such as coronal mass ejections and radio lobe propagation. The Plasma Bubble Expansion Experiment (PBEX) explores this process in a controlled laboratory setting using a compact coaxial plasma gun to generate and launch high-density argon plasma bubbles into a uniform transverse magnetic field within a linear chamber. A weakly magnetized background plasma is present to simulate interaction conditions representative of space and astrophysical environments. This study focuses on the formation and evolution of magnetic Rayleigh-Taylor (MRT) instabilities that arise at the bubble interface during expansion and examines how Hall effects influence the experimental behavior of the system. To support these investigations, the gas injection system has been optimized to precisely control the initial argon fill pressure, reducing variation in breakdown timing and improving the formation of the plasma bubble.

Diagnostics include a high-speed framing camera, a B-dot probe array, and multi-tip Langmuir probes to capture the evolution of magnetic fields, plasma density, and temperature versus time. Together, these measurements provide insight into instability growth and the physical mechanisms governing plasma bubble dynamics in magnetized background plasma environments.