Abstract
The analysis of the results of electrooptical measurements using the Kerr effect at the prebreakdown stage of an electric discharge in water made it possible to estimate the intensity of the inception field of the anode streamer. The electric field strength and phase difference distribution were constructed using computer simulation in the point-to-plane system near the anode tip. The conditions of an actual experiment are simulated. It turned out that taking into account the nonlinearity of the relative permittivity and saturation of polarization leads to a sharp increase in the field strength in a narrow region near the needle tip and compression of both the strong field region and compression of Kerr fringes. Taking these factors into account made it possible to explain the unusual shape of the chronogram and to estimate the field strength of the appearance of the anode streamer as$E$~ 40–50 MV/cm.