A tool for force model analysis for plasma armature railguns

The authors demonstrate the use of the Chapman-Kirk method for identification of force parameters in a relatively simple nonlinear differential equation model of railgun projectile motion. Where other methods of parameter identification failed, this method converged well. The data used to demonstrate the procedure are a limited set of CHECMATE data (three shots at approximately the same conditions) and one shot from another gun. The input data to the procedure are the measured current and B-dot time position data. Although the analysis of the results does not show that the model is adequate and correct over a wide range of operative conditions, the force parameters obtained are reasonable and some are substantiated by other methods. The procedure described should be a useful method to obtain railgun force parameters and, if used over a wide range of operating conditions, may help in modeling railgun projectile motion