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Abstract
Magnetosphere Plasma dynamics(MPD), encompassing plasma flows guided by magnetic fields must address how magnetically confined plasma detaches from magnetic structures where there is a significant research gap in accurate simulation techniques to simulate such environments accurately. This paper compares magnetohydrodynamic(MHD) models and computationally heavy particle in cell(PIC) simulations in cases for flow detachment applications magnetosphere, Plasma propulsion and magnetic nozzles. The work begins with an in-depth review of the theoretical foundations of magnetospheric physics and principles underlying plasma dynamics. A detailed numerical model is developed using both PIC and MHD framework to simulate plasma behaviour in magnetospheric regions. The study highlights the role of magnetic field topology in directing plasma flows, regulating energy conversion, and shaping large-scale structures such as magnetotails, cusps, and artificial magnetic bubbles along with applications in Magnetic nozzles. Simulations explore various magnetic configurations to identify conditions that optimize detachment, energy dissipation, and plasma escape. This work introduces a converging diverging B field and detachment scenarios relevant to both natural and artificial magnetospheres, to study verify and validate plasma behaviour against data driven models. Previous studies solved ideal magnetohydrodynamics equations analytically for plasma flow in expanding magnetic geometries, demonstrating that effective flow detachment is significantly difficult to achieve in artificial magnetospheres with a requirement to sufficiently extended magnetic structures. This paper develops a Lagrangian MHD code to simulate steady-state kinetic plasma flows, moving beyond analytical limitations to assess the efficiency and stability of magnetospheric configurations. The paper develops on a detailed numerical model using the generalised Ohms law, MHD and PIC codes and compares the results against a detailed parametric study with an aim to selectively trade-off between simplification and accuracy of the numerical model. The code, validated against analytical results, explores conditions applicable to natural magnetospheres and to emerging concepts of artificial magnetospheres for spacecraft propulsion(Primarily the VASIMR case study) and radiation shielding.
The results of SAMSA and COMSOL solver simulation and analytical comparison show significance of the generalised Ohm's Law primarily the Hall term in Applied field environments. The study also shows success in parametrisation which can lead to discretised models for Thrust, Plasma velocities and momentum exchange equations which can be discretely inputted within solvers. This shows significance of model simplification and how magnetosphere dynamics can be simplified in simulation alternative to computationally heavy solvers.
