Spherical stratification of a glow discharge

Abstract

Spherically symmetrical strata ͑striation͒ in a dc glow discharge were discovered. Experiments were carried out in a low-pressure steel chamber that served as a cathode. An anode was placed in the center of the chamber. The stratification of the glow discharge was observed in some molecular gases: air, N 2 , O 2 , CO 2 , and acetone vapor. A simple relation between strata radii and their number r n /r nϪ1 ϭ␣, where ␣ϭ1.4-2 ͑depending on gas composition͒, were found. Gas pressure dependences of strata radii were measured. The values of bulk charge and electric potential radial distributions were estimated. A simplified Boltzmann equation for the electron energy distribution function ͑EEDF͒ in spherical geometry was used for theoretical consideration. The so-called ''black wall law'' assumption was used in the collisional integral. An analytical solution for the isotropic part of EEDF was obtained. The existence of converging and decaying stagnant waves reproducing the variation of the observed strata radii was shown. ͓S1063-651X͑98͒03709-X͔ PACS number͑s͒: 51.50.ϩv, 52.80.Hc

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

“…When the electron sheath between the fireball and electrode reaches the ionization potential of the neutral gas, a second fireball would be predicted to form by the same mechanism as described in section 6.2. Indeed, such multiple fireball formation has been observed [261,262,263,264,265,266,267,268,269,270,271,272,273]. These usually take the form of concentric spheres or hemispheres, as shown in figure 35 [261,263,264].…”

Dust Solitons in Reactive Plasma of a Spherical Glow Discharge

“…A spherical stratification appears in high-molecular gases (acetone, ethanol, methane, acetylene) at low gas pressures (P = 0.1 -0.5 Torr) several seconds after the discharge is switched on. Spherical stratification represents a set of closed concentric lighting regions around a positive "point-like" anode placed inside a metal vacuum chamber whose wall serves as a cathode [9,10].…”

“…The series of experiments were performed in the plasma chemical reactor which was used for the investigations of spherically striated DC discharge [8][9][10]. This periodic process has a completely different nature in comparison with the processes observed earlier and needs careful consideration.…”

Flower-Shaped Strata

“…As a rule, they take the shape of luminescent transverse stripes or the shape of zones separated by dark spots [3], [4]. Along with them, 3-D strata could exist in the form of concentric spheres of various diameters [5], [6].…”