Fast Magnetic Reconnection and the Hall Effect

Magnetic reconnection is one of the most complex processes known for converting energy from magnetic fields to particle motion. It takes place in solar flares and regions of planetary (and stellar) magnetospheres. Having been studied since the 1950s, many details of the process are still undergoing study.

One of the key components in magnetic reconnection is the collision of two magnetic field regions with opposite-directed field lines, imbedded in a plasma. The field and plasma combination forms an X-shaped configuration at their closest, and most intense point.

These visualizations are plotted from a reconnection model generated by VPIC (Vector Particle-In-Cell) code. Quantities are plotted in 'dimensionless' coordinates, that are normalized to the ion inertial length (di).

The magnetic vector potential is represented by the blue-green curves which dip inward from the top and sides of the plot. This forms the 'X' region that confines the electric current (gold) which is directed out of the plane of the plot (towards the viewer). The Electron Diffusion Region (EDR) is the intense horizontal oblong blob near the center of the plot.

Electrons and ions (plasma) flow into the region from the top and bottom of the plot, initially moving together. As the plasma moves into regions with less intense magnetic field and stronger electric current, the ion and electron trajectories begin to diverge, driven by the Hall effect (Wikipedia). This accelerates and channels the flow of particles outward, through the left and right wings of the 'X', where the magnetic energy density is lowest. The net process is magnetic energy is converted into particle energy.

The incoming magnetic energy is diverted and transported to the downstream region leaving an energy void at the X-line.

See NASA.gov