Particle Trajectories at a Magnetic Neutral Point

Abstract

The motion of charged particles is studied numerically by a test-particle approach. A Petschek-type electromagnetic field is given for a plasma in which a finite electric conductivity, necessary at a magnetic neutral point, results from the inertia of the particles. The plasma is assumed to be cold in the external flow region. It is found that two gyration frequencies characterize the motions parallel and perpendicular to the external magnetic field. The meandering electrons are concentrated near the neutral point and have a mean velocity, though with a considerable dispersion, big enough to cause some current-induced instabilities.