Plasma-fluid interaction and arc resistance in electrothermal launchers

The comparison of numerical simulations with real electrothermal shots has provided new insight into the plasma-fluid and plasma-wall interaction processes. Strong indications are given for the following effects: in addition to wall ablation by radiation, there is a nearly time-independent ablation rate, which may be attributed to direct heat transfer. In the presence of liquid inside the discharge tube, an enhanced mass flow into the plasma is hypothesized and attributed to a deformation and hence an enlargement of the area of interface between vapour and plasma. No indications are found for a significant turbulent mixing of plasma and vapour; vapour accumulating near the breech has no beneficial effect on projectile acceleration