The role of convective flow processes in determining plasma armature characteristics

As railgun performance proceeds toward higher velocity ranges and/or more exotic geometries, entrainment of the armature in turbulent boundary layers at the wall or differential transverse force loading on the armature can lead to the development of convective flow within the armature. The effects of such flow were investigated and were shown to give significant departure from the usual zero-flow models. Specifically, such effects lead to: (1) peaking of the armature current toward the projectile/armature interface at sufficiently high projectile velocities, in agreement with B_z measurements; (2) a possible upper limit on total armature mass; and (3) transition to an armature resistance that is relatively independent of resistivity but is dependent on the bulk convection velocity