Theoretical Computation of Anomalous Resistivity for Substorm and Reconnection Onset

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The proposed research project comprises a theoretical study of the non-linear theory of anomalous resistivity in thin current sheets. Anomalous resistivity is thought to play an important role in the triggering of magnetic substorms in Earth's magnetosphere. The concept of anomalous resistivity is widely invoked in the literature, but no systematic theoretical discussion has been carried out which can be readily applied to the problem of magnetic reconnection. This project will develop a self-consistent theory of anomalous dissipation which arises from the excitation of a high-frequency electromagnetic instability called the modified-two-stream instability and the lower-hybrid drift instability. These instabilities are likely to be active in thin current sheets just prior to the onset of reconnection. In contemporary research on reconnection (both theory and simulation), the simple Harris model is usually used as the starting point. However, the current sheet structure just prior to the substorm onset cannot be described adequately by the Harris model. The proposed research will therefore model the current sheet structure by generalizing the customary Harris model. The methodology will be a non-local, kinetic, linear Vlasov theory coupled with quasilinear treatment of the anomalous transport coefficient. The theoretical equations will then be solved by numerical means. The notion of excitation of electromagnetic fluctuations being correlated with the onset of substorm or reconnection derives from well-established (but poorly understood) experimental evidence such as the MRX laboratory experiment and AMPTE spacecraft measurements.