Study of Plasma Wave Propagation Based on Magnetotail MHD Modelling

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We have clarified propagation characteristic of various kinds of plasma waves in the magnetotail based on the MHD simulation model which gives a self-consistent model of the magnetic field and plasma density. We first used a 2D MHD model of a plasmoid in the magnetotail region. After clarifying the propagation characteristics of various kinds of plasma waves in the 2D model, we extended the study to a 3D model. In applying the MHD models to the ray tracing, we introduced a new method to interpolate the plasma density and the magnetic field from those defined at the discrete spatial grid points, while the density and magnetic field models are given as an analytic functions in the previous ray tracing studies. We assumed a source of the plasma waves in the X-point reconnection region associated with the plasmoid. We traced the propagation paths of the various kinds of electromagnetic waves for all possible propagation angles. We obtained a "ray density" from the spatial distribution of the rays. We obtained the ray densities for various electromagnetic waves in the range from a very low frequency less than the ion cyclotron frequency up to the high frequency higher than the electron plasma frequency. Through visualization of the ray densities in the 3D model via the AVS graphic system, we have identified the propagation characteristics of ion cyclotron waves, lower hybrid waves, whistler mode waves, L-O mode waves in the magnetotail. Based on the database of the ray density, we simulated dynamic spectra of electromagnetic waves as observed by a spacecraft which traverses the plasmoid in the magnetotail.