Magnetic field shielding of electromagnetic launch missile

Over the past three decades, electromagnetic launch technology has made significant progress. Some researchers have begun to study the missile which is accelerated by a railgun to supersonic speed. Compared to conventional missile, an electromagnetic launch missile has the advantages of high muzzle velocity and strong concealment. However, a railgun represents a harsh electromagnetic environment for the missile. Pulse current in the railgun can produce a high amplitude and broad spectrum magnetic field. Electromagnetic interference might affect any sensitive electrical devices that the missile is being equipped with. For this reason, it is necessary to study the missile magnetic field shield in rail launcher environment. This paper has built 3D model of the railgun and missile. Using finite-element analysis, we study separately missile inner magnetic field distribution under various shielding configurations, including monolayer shield, multilayer shield and the shield body with having hole. The shielding effectiveness (SE) of various shielding configurations is presented. Based on the above results, we design a kind of double layer shielding for missile in railgun. And this paper investigates the impact of the drilling point the hole size and the opening directions in shielding performance. In addition, we found that the electromagnetic force on the armature, namely, inductance gradient becomes large because of magnetic field shielding of missile. The relation between inductance gradient and shield has been analyzed. Study shows that inductance gradient is increased by 20%.