Abstract
The energetics of a current sheet that forms between newly emerging flux and an ambient field are considered. As more and more flux emerges, so the sheet rises in the solar atmosphere. The various contributions to the thermal energy balance in the sheet are approximated and the resulting equation solved for the internal temperature of the sheet. It is found that, for certain choices of the ambient magnetic field strength and velocity, the internal temperature increases until, when the sheet reaches some critical height, no neighbouring equilibrium state exists. The temperature then increases rapidly, seeking a hotter branch of the solution curve. During this dynamic heating, the threshold temperature for the onset of plasma microinstabilities may be attained. It is suggested that this may be a suitable trigger mechanism for the recently proposed ‘emerging flux’ model of a solar flare.
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This work was done while the author was participating in the CECAM workshop on ‘Plasma Physics applied to Active Solar Phenomena’, August–September 1976 at Orsay, France, and the Skylab Solar Workshop on Solar Flares (sponsored by NASA and NSF and managed by the High Altitude Observatory).
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Tur, T.J., Priest, E.R. A trigger mechanism for the emerging flux model of solar flares. Sol Phys 58, 181–200 (1978). https://doi.org/10.1007/BF00152563
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DOI: https://doi.org/10.1007/BF00152563