Magneto-hydrodynamics simulation study of high-density plasmas in electromagnetic guns

摘要

Electromagnetic plasma guns use Lorentz forces to accelerate high density plasmas to velocities ～km/s. This concept has been used widely in space propulsion systems and in thermonuclear fusion devices. One of the important factors that influence the performance of these devices is the interaction of the high density plasma with the bounding solid surfaces. We perform a numerical modeling study of the plasma in an electromagnetic gun to understand the discharge physics and in particular study the plasma-surface interactions. We use the resistive Magneto hydrodynamics (MHD) equations which include the mass, momentum and energy equations for a conducting fluid along with the Maxwell's equations to study the plasma phenomenon in these devices. The equations are solved on an unstructured mesh using a cell-centered finite volume formulation. Simulations are performed on the operation of a generic plasma accelerator in the plasma detonation mode with current inputs ~ 400-1200 kA/m. Results obtained reveal the formation of a current sheet that propagates from the breech to the muzzle. It is also seen that the viscous shear stresses and thermal fluxes at the electrodes are dominant in the region of the current sheet. The time averaged viscous drag acting on the plasma is seen to increase rapidly with the current input.