Neutral Point Discharge Experiment

Abstract

The behavior of a plasma current through a magnetic neutral point is investigated experimentally. A quasi-steady magnetic field (either cusp or quadrupole magnetic field) is created by a slow capacitor discharge, and the plasma sheet current is excited by a slow capacitor discharge. The plasma current sheet thus formed is collapsed into small filamentary pinches, and they are ejected outward on the current sheet plane along the magnetic field lines. This seems to correspond to the ejection of plasma and energetic particles associated with solar flares. The visual observation together with double probe and Rogowski coil measurements shows that the collapse of the plasma current occurs earlier as the plasma current and the external magnetic field is increased and as the initial gas pressure is decreased, and this is explained qualitatively by the resistive tearing mode instability.