Relating conductivity, muzzle voltage, and projectile velocity in plasma armature railguns

Summary form only given. The value of the conductivity calculated using the muzzle voltage and current does not agree with the predicted values for a plasma based on measured temperature, pressure, and species. It is shown that this consistency may be resolved by relating the muzzle voltage measurement to both the conductivity of the plasma and the plasma velocity in the magnetic field at the leading edge of the arc. With this relationship there is a correlation between the conductivity and the changing plasma state conditions as well as a better match between experimental and predicted conductivities. But it also leads one to different conclusions about the energy dissipated in the plasma. The circuit relations have been combined to make some predictions about the rate of change of the length of the armature and an extension to its effect on the velocity of the projectile.