Influence of Nanoparticles and Metal Vapors on the Color of Laboratory and Atmospheric Discharges

Abstract

Currently, electrical discharges occurring at altitudes of tens to hundreds of kilometers from the Earth’s surface attract considerable attention from researchers from all over the world. A significant number of (nano)particles coming from outer space burn up at these altitudes. As a result, vapors of various substances, including metals, are formed at different altitudes. This paper deals with the influence of vapors and particles released from metal electrodes on the color and shape of pulse-periodic discharge in air, nitrogen, argon, and hydrogen. It presents the results of experimental studies. The discharge was implemented under an inhomogeneous electric field and was accompanied by the generation of runaway electrons and the formation of mini-jets. It was established that regardless of the voltage pulse polarity, the electrode material significantly affects the color of spherical- and cylindrical-shaped mini jets formed when bright spots appear on electrodes. Similar jets are observed when the discharge is transformed into a spark. It was shown that the color of the plasma of mini-jets is similar to that of atmospheric discharges (red sprites, blue jets, and ghosts) at altitudes of dozens of kilometers and differs from the color of plasma of pulsed diffuse discharges in air and nitrogen at the same pressure. It was revealed that to observe the red, blue and green mini-jets, it is necessary to use aluminum, iron, and copper electrodes, respectively.

Ionization Waves, Propagating in Opposite Directions, as in Red Sprites

“…Nevertheless, we believe that such discharges near notilucent clouds initiate, with sufficient E/N, the formation of ionization waves -sprites. In should be noted that in some cases, at high altitudes, sprites are initiated by micrometeors [32], [33]. At the initial stages, the direction of downward movement of sprites is set by E, which should be directed from the place where a sprite appears to a negatively charged surface.…”

Thin Luminous Tracks of Particles from Electrodes with a Small Radius of Curvature in Pulsed Nanosecond Discharges in Air and Argon

“…Finally, traces of luminous particles in atmospheric air discharge, formed by nanosecond voltage pulses, were discovered in recent works [22,23]. Figure 3 in [22] shows an image in which two streamers propagate from a particle in opposite directions.…”

Experimental Simulation of Red Sprites in a Laboratory

“…Preliminary experiments have shown that such a discharge are red colored due to the emission of bands formed by spectral transitions of the 1+ system of a nitrogen molecule and are can be classified as a streamer discharge. This paper, unlike others dealing with laboratory modeling of red sprites in low-pressure air [15,[26][27][28][29][30][31] , has a significant difference in the form of an electrodeless discharge.…”

“…The experiment was aimed at determining the influence of the polarity of a high-voltage (HV) electrode on the formation of streamers at low air pressures, as well as fixing their color at pressures of 1 Torr ~ 3 Torr, at which the sprites still remain red. However, the color of the pulsed discharge at low pressures can be either blue or violet [15,[26][27][28][29][30][31] . DC voltage of positive or negative polarity from the U DC source was applied via a 3-m-long cable equipped with a 100-MΩ resistor to the additional electrodes mounted on the left flange (Figure 3a).…”

“…As a result, breakdown in an inhomogeneous electric field occurs at a positive polarity of an electrode with a small radius of curvature at a voltage 2-3 times lower than at a negative one (see, e.g., [33] ). At nanosecond voltage pulses and low pressures, the color of the discharges was blue or violet [23,[26][27][28][29][30][31] (without taking into account the influence of the interelectrode material [30] ). Under the conditions of the experiments, the color of plasma emission both in the region where streamers propagate and in the region near the electrodes was red, including at the air pressure in p = 6 Torr ~ 9 Torr, at which streamers were not observed.…”