Thermal characteristics of a laboratory EM launcher

Performance of rail conductors under rapid-fire conditions is limited by the ability to remove the heat generated during each shot. The net thermal effect of each shot is to raise the bulk temperature and induce thermal stresses in the conductors. While the high bulk temperature reduces the strength of the material, the cyclic thermal stress may reduce fatigue cycle life of the components. Various estimates of cooling requirements in rail conductors have been done using one-dimensional (ID) and two-dimensional (2D) approximations. In this study, we carried out a three-dimensional (3D) motion computation of the thermal load experienced by the entire length of a laboratory EM gun for a single shot firing. The distribution of thermal energy deposited in the rails is compared with the prior solutions. Post-transition energy dissipation and voltage rise due to arcing contact are also characterized.