Electromechanical Modeling of Components of a Linear Electromagnetic Accelerator

Linear electromagnetic accelerators of the railgun-type are characterized by their capability to reach very high end velocities of more than 2 km/s for masses in the range of several hundred grams. The acceleration technology is characterized by the use of transient (ms-range) current pulses with amplitudes up to the mega-ampere range. Therefore, the layout of components has to consider the large magnetic forces acting on current-carrying conductors. Particular attention has to be paid to the contact regions between different conductors, as at these locations small mechanical deformations can lead to the formation of electric arcs. While in the past, the layout of electromechanical components had to base primarily on empirical knowledge, today's finite element software packages allow to model their behavior. In this paper, the 3-D-FEM software package COMSOL is used to investigate the electromechanical behavior of components of a railgun. The analysis starts with simple geometries assuming only the electric behavior and is extended to electromechanical calculations. The current distribution, the distribution of the magnetic forces as well as mechanical stresses and strains are calculated and discussed for several examples. Among the topics is one of particular interest for linear accelerators of the railgun-type: recoil.