Interaction of counter-streaming plasma flows in dipole magnetic field

TL;DR

This study investigates how counter-streaming super-sonic plasma flows interact within a dipole magnetic field in a laboratory setting, revealing new behaviors of plasma expansion and magnetic field disruption.

Contribution

It demonstrates that laser plasma can disrupt and carry magnetic fields beyond the magnetosphere, differing from previous models and expanding understanding of plasma-magnetic field interactions.

Findings

Laser plasma carries a magnetic field larger than the vacuum dipole field at large distances.

No magnetic field compression at the plasma front was observed.

Laser plasma picks up and transports a magnetized shell from background plasma.

Abstract

Transient interaction of counter-streaming super-sonic plasma flows in dipole magnetic dipole is studied in laboratory experiment. First quasi-stationary flow is produced by teta-pinch and forms a magnetosphere around the magnetic dipole while laser beams focused at the surface of the dipole cover launch second explosive plasma expanding from inner dipole region outward. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. Probe measurements showed that far from the initially formed magnetosphere laser plasma carries within itself a magnetic field of the same direction but order of magnitude larger in value than the vacuum dipole field at considered distances. Because no compression of magnetic field at the front of laser plasma was observed, the realized interaction is different from previous experiments and theoretical models of laser plasma expansion into uniform magnetized background. It was deduced based on the obtained data that laser plasma while expanding through inner magnetosphere picks up a magnetized shell formed by background plasma and carries it for large distances beyond previously existing magnetosphere.