PARAMETERS OF THE POSITIVE CORONA DISCHARGE STRIMER IN AIR IN ELECTRODE SYSTEM: A NEEDLE AND METAL DISK – PLANE

Abstract

The paper is devoted to the study of the streamer propagation in a specific electrode system with a needle, the length of which is limited by a metal disk. The aim of the work is to determine the influence of the length of thin cylindrical needle in the electrode system with a metal disk on the streamer parameters during its propagation in a sharply inhomogeneous electric field of the positive corona discharge in air at atmospheric pressure. Experimental data are presented on the influ-ence of the needle length and the voltage between the electrodes on the pulse and time-averaged current value during the appearance of streamers. In the calculated part, an approximate one-dimensional mathematical model of the formed streamer propagation was applied. According to calculations for different needle lengths depending on the coordinate of the propagating streamer head, the following streamer parameters were determined: the charge of the head, its radius and propagation velocity, as well as the currents corresponding to the movement of the charge and the charging of the streamer channel. It was found that the component of the current associated with the movement of the positive charge of the formed streamer head is significantly smaller compared to the component of the current charging the streamer chan-nel. Since plasma-chemical processes occur mainly near the streamer head, the distinguish of the corresponding current component in the experiment or determination by the calculation method appears to be a relevant issue. The increase in the size of the streamer head and the simultaneous decrease in the time for the streamers to cross the gap between the elec-trodes, detected with increase in the needle length, indicate the possibility of the existence of the needle length that is opti-mal in terms of the efficiency of the plasma-chemical reaction. References 17, figures 5, table 1.