Physical mechanism of spontaneous fast reconnection evolution
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2001
Received: 26 May 2000
Accepted: 5 December 2000
Published: 26 June 2014
Large dissipative events, such as solar flares and geomagnetic substorms, result from sudden onset of magnetic reconnection, so that it is a long-standing problem to find the physical mechanism that makes magnetic reconnection explosive. As recognized by Petschek, standing slow shocks enable the effective magnetic energy conversion in space plasmas of extremely large magnetic Reynolds number. Hence, a basic question is how the fast reconnection mechanism involving slow shocks can be realized as an eventual solution? We have proposed the spontaneous fast reconnection model, which describes a new type of nonlinear instability that grows by the positive feedback between plasma microphysics (current-driven anomalous resistivity) and macrophysics (global reconnection flow). It is demonstrated that the fast reconnection mechanism explosively grows by the positive feedback in a variety of physical situations; for the larger threshold of anomalous resistivity, the fast reconnection evolves more drastically. Also, distinct plasma processes, such as large-scale plasmoid and magnetic loop dynamics, result directly from the fast reconnection evolution. Even in general asymmetric situations, the spontaneous fast reconnection model effectively works, giving rise to drastic magnetic flux transfer.