New electro-mechanical concepts of the primary mechanisms of electrical breakdown in liquids

Using a generalisation of the theory of electrocapillarity, it is shown that an electrical field E in a dielectric liquid will generate a mechanical tensile stress ε E² which is everywhere orthogonal to the electrical field. For fields between 10⁸ and 10⁹ V m^-1 the mechanical stress is sufficient to enhance significantly the thermal generation of sub-microscopic cracks (holes) in the liquid. When the hole concentration is large enough, the same stress will encourage the propagation of cracks through the liquid by the Griffith´s process which is well known for the fracture of solids. Streamer growth is considered in terms of this mechanical model and it is suggested that electrical discharges have a secondary rather than a primary role in the process