CONDITIONS FOR THE EMERGENCE OF POSITIVE STREAMER CORONA DISCHARGE IN AIR IN THE NEEDLE-TO-PLANE ELECTRIC FIELD

The features of the positive streamer corona discharge are the long length and the duration of each streamer. They de-fine this type of discharge as one of the alternative paths of potential technological application and characterize the relevance of research in this direction. The aim of the work is to determine the influence of the geometric characteris-tics of the needle and the voltage between the electrodes to the size of the areas, the beginning of the development of electron avalanches from which leads to their transformation into a streamer form of corona discharge in air at atmos-pheric pressure. For electrode systems with needles in the form of hyperboloid and paraboloid of rotation, sphere and 10.15407/long cylinder, the electric field distribution is considered and the volume of the areas where the appearance of effective initial electrons leads to their multiplication to the stage of avalanche-streamer transition in the strongly inhomogeneous electric field is determined. It is established that the size of the specified volumes, in addition to the curvature radius of the tips, is significantly affected by the shape of the electrode outside the part of its surface with the smallest radius of curvature. It is shown that despite the smaller values of the maximum field for the hyperbolic needle, here the volume of the appearance of effective initial electrons can exceed the volume for cylindrical and even more so for spherical electrodes of the same tip curvature radius at the same value of voltage. A feature of the long cylindrical needle is the extension of the start zone of the effective electrons over a considerable distance along the cylindrical sur-face of the electrode. From the comparison of different electrode systems, it was concluded that the choice can be made according to the magnitude of the volumes of appearance of effective electron, as a quantitative indicator that takes into account the needle configuration, tip radius, and value of voltage. References 24, figures 6.