Transient simulation of shielding helical coilgun

The shield material properties and its structure are important to the coilgun´s performance. In present article, a two-dimensional (2-D) transient finite element model was established based on the structural characteristics of the coilgun and launching process. Effects of variable shield materials with different dimensions on the launching performance have been investigated. The magnetic field distributions at different times have been presented. The results show that, the eddy currents induced in the conductive shield will reduce the projectile´s muzzle velocity, and the electromagnetic shielding effect of the conductor is not ideal. Strengthening the main magnetic flux, permeable non-conductive material shield increases the muzzle velocity of the projectile, and the electromagnetic shielding effect is good. Increasing the thickness of the shield, the magnetic materials enhance the magnetic flux better, projectile muzzle velocity increases, and the electromagnetic shielding effects are better. In order to achieve higher projectile muzzle velocity and better electromagnetic shielding effects, high permeability silicon steel sheets can be used as the shield. The distance between coils and shield should be reduced. The thickness of silicon steel sheets should be as small as possible to reduce eddy current effects.