Transient modelling of a linear induction launcher-type coil gun with two-dimensional cylindrical finite-difference time domain method

Two-dimensional (2D) simulation of a linear induction launcher-type coil gun is performed by the cylindrical finite-difference time domain (FDTD) method. Maxwell´s equations in cylindrical coordinates are used to formulate the problem. Circular symmetry is assumed for reducing the 3D problem to a 2D one. A singularity that appeared at r=0 is extracted by using the integral formulation of the FDTD method. A special quasi-static approximation of the FDTD method is applied in the cylindrical problem space which is terminated with the second-order Mur absorbing boundary condition. The armature movement in the FDTD method is treated by the quasi-steady-state method. An experimental model was built, and the muzzle velocity was measured for comparison with the calculated value. Good agreement was obtained.