Resistive Tearing Mode Instability Research Articles

Energy Release by Magnetic Tearing: The Nonlinear Limit

The nonlinear limit of the resistive tearing-mode instability is investigated by a time-dependent solution of the Fourier-transformed magnetohydrodynamic equations. The calculation is started with the fastest-growing linear mode and assumes a constant (e.g., turbulent) resistivity. Attainable magnetic Reynolds numbers are limited by the steep spatial gradients developed and by the propagation of Alfven waves in the system. At the largest values used, 10% of the background energy is released in nonthermal forms. The time and energy scales found are consistent with the results of astrophysical observations and laboratory studies of solar-flare processes.

Neutral Point Discharge Experiment

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.