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A Model for Spontaneous Onset of Fast Magnetic Reconnection

P. A. Cassak·J. F. Drake·M. A. Shay
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Abstract

We present a model for the spontaneous onset of fast magnetic reconnection in a weakly collisional plasma, such as the solar corona. When a current layer of macroscopic width undergoes collisional (Sweet-Parker) reconnection, a narrow dissipation region forms around the X-line. This dissipation region naturally becomes narrower during the reconnection process as stronger magnetic fields are convected toward the X-line. When the dissipation region becomes thinner than the ion skin depth, resistive magnetohydrodynamics breaks down as the Hall effect becomes important and the Sweet-Parker solution ceases to exist. A transition to collisionless (Hall) reconnection ensues, increasing the reconnection rate by many orders of magnitude in a very short time. Predictions of the model are consistent with constraints set by observations of solar flares.

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P. A. Cassak, J. F. Drake, M. A. Shay. 2006-03-31. A Model for Spontaneous Onset of Fast Magnetic Reconnection. https://doi.org/10.1086/505690

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