On the Mechanism of Electromechanical Breakdown of Solids in Strongly Nonuniform Fields in Absence of Ionization and Space Charges

Electric forces acting on a neutral matter in nonuniform electric fields may generate mechanical stresses even in the absence of charged species. This mechanism is invoked here as a factor in solid dielectric breakdown (BD). Analytical estimates and numerical simulations for point-to-plane gaps matching experimental conditions show that the electric forces arising in strongly nonuniform fields can be of the order of GN/
$\text{m}^{{3}}$
. Stress analysis for practical voltage levels predicts stresses inside the dielectric of the order of several megapascals, which exceeds yield stress of many technical insulating materials including those used in our experiments. Thus, solid insulation can be mechanically damaged just by the electric forces. This appears to be an unnoticed mechanism of electric BD in solids in a nonuniform field. It may be a dominant mechanism or a part of complex combination of other processes, such as ionization and avalanching, field emission, microdefects generation, and so on.