Railgun armature plasma-current density from deconvolved B-dot probe signals

It is shown that the spatial distribution of the moving armature current profile in an electromagnetic railgun can be recovered from the recorded signal of a B-dot probe. This approach differs from previous methods in that no a priori assumptions for the functional form of the armature current density are required. From certain simplifying assumptions, a model of the railgun circuit is developed from which the B-dot probe signal can be derived as a convolution of the armature current density with an impulse-response function dependent on the physical parameters of the experimental configuration. Deconvolution of the resulting signal corrupted with measurement noise is performed using a parametric Wiener filter. Simulated and actual numerical examples show that the physical length and overall shape of the armature current profile can be accurately determined using this method. However, the spatial resolution in the deconvolved signal is limited to approximately 1 to 2 cm for practical railgun applications