Evaluation of railgun inductance by 2-D transient FE analysis

The inductance per unit length (L´) of a railgun barrel is one of the principal parameters to predict the acceleration performance of a complete railgun system. A method is proposed to evaluate L´ using the vector potential of the inside of rails obtained by two dimensional transient electromagnetic analyses with the finite element method for cross-sections of railgun barrels. Calculations with the method were carried out for two types of existing barrels. It was confirmed that typical features of the evaluated values agreed well with those of the measured ones. It is also shown that the values are useful for predicting the performance of the whole railgun system with a railgun system simulation code. Finally, parametric studies were carried out for one of the barrel models assessing the effect of changing several design parameters. From these results an idea of a thin steel wire wound barrel is proposed