Tearing driven reconnection : interplay between heating and kinetic instabilities (2D hybrid Möbius simulations)
Abstract :
In this talk, we present results from two-dimensional hybrid simulations using modified periodic conditions with a topology akin to a Möbius strip. Our primary focus is the global energy conversion during the non-linear stage of the tearing instability. We find that part of the magnetic energy is transformed to the kinetic energy through the electric work rate, and, at about the same time, part of the kinetic energy is transformed to the plasma thermal energy through the pressure-strain coupling. These rate of energy exchanges are of the same order, but not homogeneous. Conversion to thermal energy predominantly occurs within the magnetic islands, while near the X-points, most of the energy conversion goes from magnetic energy to bulk plasma flow. Moreover, the global pressure strain interaction is mostly (about 75 %) incompressible. Signatures of the proton firehose instability are also observed within the magnetic islands, located between the different reconnection sites. The firehose instability, caused by the proton temperature being higher parallel than perpendicular to the local magnetic field, constrains the plasma temperature anisotropy. This instability thus regulates the conversion of bulk speed to thermal energy as indicated by the temporal evolution of the pressure-strain interaction, and is also expected to convert back some of the thermal energy to magnetic energy through plasma oscillations.
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