| This thesis addresses several topics concerning the structure and dynamics of the magnetopause. These topics include the role of the magnetopause in global convection, the Kelvin-Helmholts (K-H) instability, which accounts for momentum transport at the magnetopause, the formation of flux ropes by the tearing and twisting modes and particle diffusion across the magnetopause resulting from the destruction of magnetic surfaces.; We first establish an analytic electric field model for an open magnetosphere and introduce a magnetopause to control the reconnection rate and momentum transport. A realistic magnetospheric configuration is realized by "stretch transformation". The role of magnetic nulls in the electric field is approached with a technique for direct calculation of electric fields along field lines. Results indicate that electric fields associated with A-type or B-type nulls are generally singular.; We then consider kinetic effects on the K-H instability. Contrary to the logical assumption that Landau damping damps the instability, it can instead enhance the growth rate and increase the spatial extent of the instability because the heating of resonance particles enhances the pressure perturbation. We use a gravitational analogy to determine the effect of curvature on K-H instability and find that the critical Richardson number for stability increases from {dollar}{lcub}1over4{rcub}{dollar} for incompressible fluids to {dollar}{lcub}1over2{rcub}{dollar} for compressible fluids.; The flux rope, which accounts for flux transfer events (FTE), can be formed by a tearing or twisting mode. The tearing mode is self excited by the free energy associated with the magnetic configuration, while the twisting mode must be externally driven. The shear flow generates the twisting mode and reduces the growth rate of the tearing mode. The flux ropes resulting from the twisting mode closely resemble FTEs which have a longer pitch length than that from tearing mode.; Particle diffusion across the magnetopause is addressed by considering the destruction of magnetic surfaces. The diffusion coefficient reaches {dollar}10sp9msp2/s,{dollar} which is critical for magnetopause boundary layer formation. The presence of regular magnetic surfaces at the edge of the current layer may account for the sharp transition that is often observed at the magnetopause. |
