Magnetic reconnection in a force-free plasma: Simulations of micro- and macroinstabilities

Two-and-one-half-dimensional particle-in-cell plasma simulations are used to study the stability of a force-free sheet pinch equilibrium, in which currents flow parallel to the sheared magnetic field and the plasma is uniform. The magnetic shear drives a long wavelength, electromagnetic tearing instability, whereas a sufficiently large current may excite a shorter wavelength electrostatic electron/ion instability. This latter instability heats electrons locally, which causes the formation of a new configuration with inhomogeneous electron density and temperature which, in turn, enhances the growth of the tearing mode. Both instabilities lead to conversion of magnetic energy into plasma particle energy, but only the tearing mode leads to significant reconnection. (C) 2003 American Institute of Physics.