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Center for Nonlinear Studies |
Magnetic reconnection energizes electrons in space plasmas, and the effective heating can be highly anisotropic. The electron temperature parallel to the magnetic field may rise to several times the perpendicular temperature. Adiabatic electron trapping turns out to play a major role in this process. I will review a general analytic model for the distribution of particles trapped by slowly varying fields and discuss when it is applicable to the electrons in a reconnection geometry. Derived from this kinetic model, a fluid closure gives equations of state for the electron pressure components. The new fluid model helps explain structures observed in kinetic simulations and in spacecraft measurements of reconnecting current sheets. In addition, the model predicts that the electron temperature will rise by the largest factor when the electron pressure is much smaller than the magnetic pressure.
Host: Jeffrey Hyman