Ring Current Ion Interaction with Magnetospheric Hydromagnetic Waves

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The primary objectives of the proposed project is to advance understanding of the interaction of ring current ions with magnetospheric hydromagnetic waves. In particular, wave excitation by magnetic drift-bounce resonance with energetic (100-200 keV) ring current protons and the self-consistent nonlinear evolution of the waves and the ring current ions (H+ and O+) will be considered. The methods employed will include (i) numerical solutions of linear gyrokinetic eigenmode equations using existing computer codes, (ii) simulations of the motion of ring current ions in hydromagnetic waves using an existing gyroaveraged Hamiltonian test particle code, (iii) development of a 3D dipole geometry magnetohydrodynamic (MHD) code and (iv) coupling of the test-particle and MHD codes to produce a hybid MHD-gyrokinetic code. The hybrid code will be developed separately on a CRAY-YMP computer and also on a massively paralle CM-2 Connection Machine. It is expected that the CM-2 MHD- gyrokinetic simulation system will be faster than the CRAY version and will be capable of handling a larger simulation region. The results will provide the first simulation of the excitation and nonlinear evolution of magnetospheric hydromagnetic waves due to ring current ions, and of the self-consistent effect of the waves on the ions. Comparisons with spacecraft data will be made to test the theoretical predictions and yield new theoretical insights into observed wave properties and associated particle measurements.