Underwater Electrical Discharge with a Large Surface of Radiation

Breakdown and formation of surface electric discharge in a zone of turbulent agitation of water jet transverse to the axis of an electrode system are studied. The jet boundary is actually a two-phase medium favorable for electron breeding consisting of cavitation microbubbles up to 10⁷ cm^-3 in volume. These features differentiate the considered discharge from a low-voltage breakdown in a stationary liquid. Abnormal properties of electric discharge in a submerged water stream take place both at the initiation and at the stationary stage. The threshold voltages are reduced by several times at the stream velocities of about 30 m/s, simultaneously the duration of the prebreakdown stage is reduced by one to two orders of magnitude. At the arc stage of the discharge, there is a developed emitting surface with plasma shell thickness being about 1 mm. The change of initial water conductivity by four orders of magnitude does not lead to large changes in breakdown dynamics.