Numerical Investigation of the Effect of a Longitudinally Layered Armature on Coilgun Performance

The effect of a longitudinally layered armature on coilgun performance is investigated by using a 2-D axially symmetric cylindrical quasi-static finite-difference time domain method. The singularity extraction and Mur-type absorbing boundary condition are adopted with the numerical solution. The results obtained show that the best coilgun performance in the sense of the induced propulsive armature force is observed when the conductivity of the outer layer of the armature is smaller than that of the inner layer. This phenomenon can be explained in terms of impedance matching based on skin depth evaluation.