The electric field inside a gas cavity formed at a solid-solid dielectric interface stressed with HV impulse

Interfaces between different solid dielectric materials often exhibit lower breakdown strength when compared to bulk solid materials. Of particular concern in many HV and pulsed-power systems are configurations in which a strong tangential field to an interface is developed. In such cases, past studies have shown that solid-solid interfaces are particularly susceptible to electrical breakdown. A reason for such reduction in dielectric strength is the presence of gas cavities formed at the interface, as a result of the inevitability that the contact surfaces will be rough. If left unchecked, this may ultimately lead to the complete and catastrophic failure of the insulation, severely compromising the integrity of the HV system. While some work has been conducted on solid-solid interfaces in steady-state AC regimes, we attempt to extend this knowledge to transient, impulsive energisation, and to better include the effects of electrical parameters such as permittivity and conductivity into our analysis.