One-Dimensional, Time-Dependent Model for Railgun Arcs.
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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Our recent, one dimensional, steady state model for describing railgun plasma armatures is extended to account for fully time dependent behavior. The formalism necessary for carrying out the extension is discussed, and the governing equations are derived in a frame of reference that accelerates with the arc. Numerical techniques appropriate for solving the time dependent equations are described. The model is then applied to study the time evolution of the plasma properties of the arc as it undergoes a collision with a heavy projectile located down-bore in the railgun. Two different approximations are taken for the arc temperature In the first the plasma is assumed to occur adiabatically. Both calculations are found to give roughly similar results and the physical significance of these results is described in some detail. A numerical computation of the voltages across the breech and muzzle ends of the rail pair is then compared with measurement whose conditions, are simulated in the model. Good qualitative agreement between theory and experiment is obtained and ways to improve quantitative agreement are discussed. We finally indicate calculations intended for the future, and suggest how this one-dimensional model may be able to elucidate the general behavior of railgun armatures. Keywords Railgun Plasma Armature Arc dynamics Electromagnetic launch.
- Electricity and Magnetism
- Plasma Physics and Magnetohydrodynamics