Plasma Dynamics of the Arc-Driven Rail Gun
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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A model is analyzed to study the electromagnetic acceleration of particles using a rail gun. Current is conducted between the rails by a plasma arc which accelerates down the rails driving the projectile. The analysis includes determining the electromagnetic fields within the gun and solving the fluid-mechanical equations of the plasma under the assumption that the flow parameters are steady in a frame that accelerates with the arc. Specifically, a set of coupled equations is derived which, when solved, yields the properties of the arc and the acceleration of the projectile. A limiting-case analytic solution to the equations is found, and an iterative technique is employed to solve the equations numerically in the more general case. The results of the calculation are applied to analyze the arc in an experiment recently carried out by Rashleigh and Marshall. In addition, the properties of the arc appropriate for a larger rail gun, such as proposed in a forthcoming experiment by Westinghouse, are investigated and some approximate scaling relations derived. The results of the calculations are compared with those of others and some suggestions for future investigations are given.