The scientists described the phenomenon of the apokamp, discovered and reproduced by them in laboratory conditions - the formation of blue and red plasma jets arising at the bend of the discharge in gases. The discovered phenomenon can be used to study light phenomena observed in the upper atmosphere at heights of tens of kilometers above regions with thunderstorm activity. The results of research by employees of the Institute of High Current Electronics SB RAS are described in more detail in the journal Physics of Plasmas. The study of diffuse atmospheric pressure discharges and their applications was supported by the Russian Science Foundation (RSF).
Scientists first observed the new phenomenon during experiments to create diffuse atmospheric pressure plasma. They noticed that plasma jets appeared perpendicular to the middle of the discharge channel. Repeating the experiments, the scientists established the place where the jet arises - the region of the plasma channel bend, and the phenomenon was named apokamp from the Greek words από - "from" and κάμπη - "bend". For the occurrence of this phenomenon, two electrodes and a pulse-periodic generator are needed, which forms high-voltage pulses. In this case, the channel of the electric discharge should bend, for example, due to the inclination of the electrodes. A plasma jet is formed from this bend. An apokamp is more likely to occur if the gas or gas mixture used contains electronegative components such as oxygen.
Apokampus plasma consists of two parts: a branch, which is in contact with one side of the channel of a pulse-periodic discharge, and a stream - a streamer (ionized channel in gas), the front of which moves at a speed of 100 - 220 kilometers per second. The plasma temperature of the apokampus in its different parts ranges from 100 to 1300 ° C.
The discovered phenomenon can be used to study blue jets (jets) and red sprites - natural electrical processes in the upper atmosphere accompanied by glow. Interest in their study has increased significantly in recent years due to the emergence of more and more advanced technical means of observation: both space stations and special aircraft-laboratories. At the moment, little is known about the nature of these phenomena.
Experiments carried out at the Laboratory of Optical Radiation of the Institute of High Current Electronics (ISE) of the Siberian Branch of the Russian Academy of Sciences have shown that many properties of blue jets and red sprites coincide with the properties of apokamps at corresponding pressures. Thus, the fronts of the blue jet and the apokamp move at the same speed, and the spectral characteristics of the blue jets and red sprites coincide with the spectral characteristics of the apokamp. In addition, the apokamp, blue jets, and red sprites are similar in color and shape. For example, blue jets also have two parts. The lower one, adjacent to the thundercloud, glows white, like the appendage in the apokamp. The upper part is shaped like a blue jet and is a streamer.
Apokampi at different pressures (in millimeters of mercury) / Eduard Sosnin.
“Since it is very difficult to study high-altitude atmospheric discharges and these works are associated with large material costs, thanks to the discovery of the discharge mode with an apokamp, some of these studies can be carried out in laboratories, creating miniature blue jets and red sprites,” added one of the authors of the work, Viktor Tarasenko. "It's much easier than in natural conditions."