Cross-correlation-based method for determining the position and velocity of a railgun plasma armature from B-dot probe signals

A method of determining the position and velocity of a plasma armature from B-dot probe signals is presented. It utilizes the physical processes governing the plasma armature current density to model the leading edge of the armature as a unit step function. This model of the current profile is convolved with the impulse response of the probe and compared with B-dot probe data via a local-area cross-correlation (LACC) coefficient. Two-parameter iteration determines the time of passage and velocity of the leading edge of the armature as the values for which the correlation is maximized. Results obtained using this technique indicate that significant improvement in accuracy for time of passage estimates can be obtained over previous ad hoc methods. Velocity estimates from individual B-dot probe signals can also be obtained