Nanosecond Surface Flashover of Ferroelectric Capacitor Ceramics at 70 kV

In this work we investigated nanosecond vacuum surface flashover of Al₂O₃, BaTiO₃-based and (Sr, Bi)TiO√-based ceramic materials. We measured ion current, mass loss and thrust of the particle beam initiated by the discharge at voltage of 70 kV and current of 4 kA with pulse duration of 15 ns in matched-load mode. We obtained average beam velocities of ~9 km/s for Al₂O₃and ~3 km/s for ferroelectric ceramics. Average ion velocities are in range of 140-170 km/s for all the materials. Ionization degree in the discharge plasma is higher (~3-9%) than previously measured for polymers. We theoretically estimated the thrust of the beam assuming that the discharge plasma is van der Waals gas in critical state.