Effect of Armature and Rails Resistivity Profile on Rail’s Electromagnetic Force and Armature Velocity

The electromagnetic force on rails is one of the most important factors that restrict the improvement of railgun performance by deforming, damaging, and reducing its life span. This force is generated by the current flowing through the rail and a magnetic field that is established in the space between the rails that acts as an outward mutually repulsive load. For decreasing the electromagnetic force on rails, we have a few options, such as changing the geometry and dimension of the armature and rails or changing the stimulated current. This paper has two parts. In the first part, we defined graded laminated armature, in which the electrical resistivity of each lamination is constant but different from that of other laminations in the whole armature. In the second part, laminated rails with various electrical resistivities and homogenous rectangular cube armatures are considered. The purpose of the calculation is to find a suitable assembly of conductors to form a laminated armature and rails to decrease the electromagnetic force on rails and obtain an appropriate performance for railgun. It is shown that we can decrease the maximum electromagnetic force on rails with rail's resistivity change and investigate an appropriate resistivity profile to increase armature muzzle velocity. The results are significant for the design and optimization of the railgun.