Effect of current variation on the dynamics of railgun plasma armatures

The effect of current variations on the behavior of railgun plasma armatures is investigated with a one-dimensional, time-dependent model. Three typical current profiles are considered: two inductive profiles, one with a time constant of 0.5 msec and the other with a time constant of 2.0 msec, and a capacitive profile. All three calculations are for an armature in a 5 cm square-bore railgun. It is observed that current variations create oscillations in the armature length, projectile acceleration, and projectile jerk. In addition, the current profile significantly affects the axial distribution of the plasma velocity, current density, and total pressure. The significance of these transients on the design of projectiles and the interpretation of diagnostic data is discussed, and suggestions for future calculations are outlined