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approvedsherwood16.pdf2016-04-06 19:32:19Alex Fletcher


Author: Alex Fletcher
Requested Type: Poster
Submitted: 2016-02-11 15:10:58

Co-authors: Bruno Coppi, Bamandas Basu

Contact Info:
Massachusetts Institute of Technology
1783 Massachusetts Ave Apt 1
Cambridge, Massachuse   02140
United States

Abstract Text:
The conventional theory of magnetic reconnection by the tearing mode in weakly collisional and collisionless plasmas involve characteristic length scales that are unrealistically small for astrophysical plasmas of interest. This fact motivates the search for modes that produce magnetic reconnection over microscopic scale distances that remain significant when large macroscopic scale distances (such as space plasmas) are considered. New modes that are driven by an electron temperature gradient can have this desired property. We consider an eighth order system of equations for the perturbed displacement, temperature, and magnetic field within the reconnection layer. These equations include the effects of viscosity, resistivity, and heat conductivity, in addition to a mode inductivity, and are derived for simplicity from a planar geometry. The solutions exhibit the expected structure within the layer and show that the thermal layer width is the primary scale distance. We find no localized modes. The imaginary part of the frequency is small and positive, indicating a dissipative instability. We show solutions for positive, negative, and zero values of the delta-prime parameter that is the driving factor of conventional tearing modes. We observe mode phase velocities in the direction of the electron diamagnetic velocity when delta-prime is zero. The solutions with positive delta-prime yield frequencies with negative real part, indicating the mode phase velocity is in the direction of the ion diamagnetic velocity. The results presented herein show that temperature fluctuations play an important role in the development of reconnecting modes.