Self-sustained dc atmospheric pressure normal glow discharge in helium: from microamps to amps

Abstract

It has been shown that self-sustained normal dc atmospheric pressure glow discharge (APGD) in helium exists in a large range of current values from 100 µA to 10 A. The plasma of this discharge is weakly ionized (one thousandth part of a per cent) and is non-equilibrium. The plasma non-equilibrium degree in the positive column depends on the discharge current values. Parameters of the cathode region stay constant over the whole current range of normal APGD.

Calculation of time dependence of the electrode surface temperature in the cathode spot of atmospheric pressure normal glow discharge

“…When the radius of the spot r s and the heat flow density q s in it do not depend on time, it follows from (13): (14) where and = is the comple mentary error function [19]. This coincides with the corresponding expression for the electrode tempera ture in the spot centre obtained [21,22] in case of the stationary and uniform heat flow.…”

“…After the discharge igni tion, the cathode surface in the spot and the gas near the spot are heated by the flow of heat released under charged particle motion in the discharge cathode sheath, which results in a local reduction of the gas density, a decrease of the discharge normal current density, and an increase of the spot radius with time. Experimental and theoretical investigations of the atmospheric pressure glow discharge parameters, as well as the temperature of the gas in the discharge cathode sheath and at the cathode surface, were carried out in a number of works [6][7][8][9][10][11][12][13][14][15][16] for the sta tionary discharge mode. But the dynamics of the indi cated values at the stage of their transition to the steady state was studied only experimentally in [12].…”

Self-Organized Anode Pattern on Surface of Liquid or Metal Anode in Atmospheric DC Glow Discharges

“…A TMOSPHERIC dc glow discharges have attracted considerable interests for various applications and fundamental studies [1], [2]. Previously, we reported an atmospheric dc glow discharge using a liquid electrode and observed anode pattern formation when we generated the discharge using a liquid anode [3].…”

Influence of the inter-electrode distance on the production of nanoparticles by means of atmospheric pressure inert gas dc glow discharge

“…It is noticed that the latter represents the spatial average of the gas temperature over the plasma volume to which the positive column contributes the most, whereas the cathode temperature follows the temperature of the gas in the cathode fall. This may be significantly lower, from several hundred to several thousand degrees depending upon current and cathode cooling, than the gas temperature in the positive column [9,13,26]. Nonetheless, an abrupt change in the tendency both of the gas temperature and the cathode evaporation rate is observed in figure 10(b) and figure 11, respectively, at a gap length of nearly 6 mm.…”

“…This is also due to the bombardment of the cathode surface by ions launched from the plasma and accelerated in the strong electric field in the cathode fall and by fast neutral molecules created in collisions with ions in the cathode fall. The cathode temperature has a significant influence on the properties of the cathode fall [26][27][28][29][30][31] and on the cathode vaporization rate. In addition, the vaporization rate and the gas temperature determine the saturation state of the vapour in the gas which in turn determines the concentration and size of the primary particles.…”