Hall effect degradation of rail gun performance

The Hall effect is discussed and shown to be large in the low-density and high-field trailing part of a plasma armature. Without Hall effect a simple one-dimensional theoretical armature model is derived. It exhibits properties expected from classical magnetohydrodynamic theory, and it shows in particular that the purely relativistic electric charge buildup on the rails is a fundamental railgun property, leading to V_breech=1.5V _muzzle. The mathematics in accounting for Hall effect phenomena is described. These are of two types: the Hall-skewing of the armature current and the superimposed plasma flow rotation. For decreasing gun current the two effects efficiently combine to eject armature plasma rearwards, thereby creating conditions for arc separation and parasitic arcs