Abstract
Introduction. Corona discharge, compared to discharges with a large concentration of electron avalanches and streamers, develops in the interelectrode gap with much larger dimensions, where streamers spread over a greater distance and, accordingly, each of them exists for a longer time. Problem. The search for methods for taking into account a significant number of factors that influence the development of positive corona discharge in technological processes determines the relevance of research in this area. Goal. To determine the influence of the geometric characteristics of an electrode system with metal disk and thin rod (cylindrical needle) of finite length opposite the plane and the voltage between the electrodes on the volume of the areas in which the beginning of the development of electron avalanches near the needle leads to their transition to a streamer form of a corona discharge in air at atmospheric pressure, as well as to obtain experimental data for the corona discharge in the electrode system with the same configuration. Methodology. Theoretical studies are based on the study of the avalanche stage of corona discharge, in which the avalanche of electrons under certain condition transforms into the streamer. The experiments use an electrode system for which theoretical calculations have been performed. Results. On the basis of calculations the regions where the appearance of initial electrons leads to the growth of electron avalanches and their transformation into streamers were found. The influence of the needle length, the tip curvature radius and the voltage between the electrodes on the volume of the corresponding regions was investigated. The influence of the needle length on the components of the discharge current and the conditions for the appearance of streamers was experimentally investigated. Scientific novelty. The proposed indicator of streamer emergence indicates the existence of a general trend in the dependences of the threshold voltage of streamer emergence on the needle length and the tip curvature radius, which was confirmed in experimental studies. Experimental results for the studied electrode system showed the existence of a needle length at which the amplitude of streamer current pulses reaches a maximum value, and the avalanche component of the total current is minimal. Practical value. The proposed quantitative indicator of the appearance of streamers in the complex takes into account the voltage between the electrodes, the tip radius and the length of the needle. It allows, depending on the purpose, to give preference to the required design of the electrode system. References 15, figures 6.