Simulation of the current distribution and the heat load of a brush projectile in a railgun with the finite element code ansys

One of the main issues of electromagnetic railguns is the heating of the solid contact between the current brushes in the projectile and the rails. The heat load of the brushes must be limited in order to avoid transition of the solid contact into a plasma contact and thus to avoid the deterioration of the rails. Therefore the heating of the contact between the rail and the current brush is studied. For the determination of the current distribution and the heat distribution the finite element code ANSYS was used. This code allows the combination of an electromagnetic and a thermal analysis. The current distribution in the brushes, obtained in the electromagnetic analysis, is used in the thermal analysis to calculate the temperature distribution. These temperatures are then re-entered in the electromagnetic analysis to adapt the temperature dependent resistivity. We compared the results of the simulations with ANSYS with experimental data obtained with a non-augmented railgun at the French-German Research institute 1SL. Analysis of the muzzle voltage can be used to determine the moment of transition. The experimentally obtained currents are used in the ANSYS model in order to calculate the temperature distribution and the action integral in the brushes at the moment of transition.