Limiting physics effects in hypervelocity railguns

The mechanisms presently thought to be the cause of the difficulties of achieving high projectile velocities with railguns are examined. In contrast to presently available models of hypervelocity railguns, a recent evaluation indicates that the major effect limiting the achievable velocity results from ablation caused by turbulent convective heat transfer at the bore of the railgun. The influence of ablation, whether caused by radiation or convection, is that a fraction of the ablated wall material is swept up into the plasma and heated and accelerated to the plasma velocity. The increased plasma mass and the energy lost in the acceleration process limit the railgun performance. The dominance of convective ablation has an effect on the strategy to be followed to achieve improved performance with hypervelocity railguns.>