Investigation of helium plasma stream dynamics across transverse magnetic field in pulsed plasma accelerator

The interaction of pulsed plasma streams with an external magnetic field plays a crucial role in plasma physics, with direct implications for magnetic confinement fusion, astrophysical plasma dynamics, and plasma–material interactions. This study presents an experimental investigation into the penetration dynamics of a pulsed helium plasma stream across a transverse magnetic field using a pulsed plasma accelerator. High-speed imaging, optical emission spectroscopy, magnetic probes, and electric probes were employed to characterize plasma density evolution, velocity profiles, current distributions, and emission spectra. The results reveal a substantial increase in plasma density in magnetized regions, attributed to enhanced ionization processes facilitated by the magnetic field. Spectroscopic analysis based on Stark broadening of He I emission lines quantified electron density variations, showing an increase from ∼3 × 1020 m−3 at 6 kV to ∼8 × 1020 m−3 at 12 kV in the absence of an external magnetic field, and a significantly higher increase to ∼4 × 1020 m−3 at 6 kV and ∼1.5 × 1021 m−3 at 12 kV under an external transverse magnetic field. The emission spectra further revealed impurity lines due to electrode erosion, with increased spectral broadening in the magnetized plasma, indicating stronger electron-density gradients and plasma compression. Magnetic probe measurements mapped the spatial distribution of the electric current and Ampère forces, revealing current vortices and the formation of compression zones in the presence of an external magnetic field. Electric probe measurements demonstrated a marked deceleration of plasma velocity under magnetized conditions, ascribed to Lorentz force-driven charge redistribution and induced polarization effects. The presence of the external magnetic field also led to the formation of magneto-Rayleigh–Taylor instability-induced fingerlike structures, altering plasma flow dynamics. These findings provide critical insights into plasma transport mechanisms in the magnetized region, with direct applications to magnetic confinement fusion, magnetized plasma propulsion, and laboratory astrophysics.