Current distribution and inductance gradient calculation at different rail geometric parameters

For the convenience of experiment, a rectangle is widely-used as the cross section shape of rail in railgun systems at present. The rail geometric parameters, especially in the section orientation, may directly affect the current density distribution in railgun structure as well as inductance gradient (L´) of the rails. Current distribution is the effective factor that determines the efficiency of an electro- magnetic launcher (EML) system. And L´ plays an important role in the performance of an EML system, moreover it determines directly the force that accelerate projectile. This paper investigates how the thickness, width and other rail geometric parameters, together with spacing, affect the current density distribution, magnetic flux density, and L´. Finite element analysis technique is employed to calculate these parameters using two-dimensional analysis. Several possible across section shapes of rail besides rectangle are discussed, respectively, including T-shape, annular shape, and waxing moon shape. The distribution of current density and L´ for various shapes and various dimensions are tabulated and compared.