Space charge and pre-breakdown bubbles formation near point electrodes under pulse voltage

Using Kerr effect charge injection from point cathode and anode in nitrobenzene in prebreakdown electric field under pulse voltage of microsecond range has been recorded. Cathode emission started at Ei=0.5MV/cm and anode - at Ei=1.0MV/cm. Negative space charge was approximately uniformly distributed around the point cathode top, and anode positive charges injection was of local nature. Prebreakdown bubbles appearance near electrodes was directly connected with charges injection from these electrodes. Theoretical analysis of the data obtained has shown that the bubbles appearance was caused by cavitation due to Coulomb forces action in the space charge region and electrohydrodynamic flows initiation.