Perpendicular Subcritical Shock Structure in a Collisional Plasma Experiment.

Area of Science:

• Plasma Physics
• Astrophysics
• Shock Wave Phenomena

Background:

• Understanding shock waves is crucial in plasma physics and astrophysics.
• Subcritical shocks, unlike supercritical ones, do not generate strong outgoing waves.
• Laboratory experiments provide controlled environments to study complex plasma phenomena.

Purpose of the Study:

• To investigate perpendicular subcritical shocks in a collisional laboratory plasma.
• To characterize the structure and properties of these shocks.
• To compare experimental findings with theoretical predictions.

Main Methods:

• Generating shocks using obstacles in supermagnetosonic outflow from an inverse wire array z pinch.
• Conducting detailed measurements of the shock structure.
• Calculating the classical resistive diffusion length and shock width.

Main Results:

• Demonstrated the existence of subcritical shocks in the experimental regime.
• Observed the formation of secondary shocks in the downstream region.
• Confirmed the absence of a hydrodynamic jump across the shock.
• Found the shock width to be approximately equal to the classical Spitzer resistive diffusion length.
• Measured minimal ion heating (<10% of kinetic energy) across the shock.

Conclusions:

• The experimental results confirm the presence of subcritical shocks in collisional laboratory plasmas.
• The absence of a hydrodynamic jump and minimal heating suggest that viscous dissipation is not the primary mechanism in these shocks.
• The findings contribute to a better understanding of shock wave physics in both laboratory and astrophysical contexts.