Study of cavitation in liquid water under the action of inhomogeneous pulsed electric fields: application to sub-nanosecond electrical breakdown

摘要

A sub-nanosecond electrical breakdown in dielectric liquids is of vital interest, e.g. for applications in high-voltage insulation and high-current switching. Liquid dielectrics in strong nonuniform electric fields are under influence of an electrostrictive force that tends to move the fluid into the regions with a higher electric field. If the voltage rise is fast enough, the liquid does not have enough time to be set into motion in order to reduce internal stress. In this case, the ponderomotive force induces significant stress in the bulk of the liquid that is manifested as a negative pressure. At the certain threshold, the negative pressure causes cavitation ruptures of the fluid. Then free electrons can be produced by emission from the surface inside the cavity and accelerated to energies exceeding the energy for ionization of water and contribute to the ultrafast electrical breakdown of water.