Experimental and Theoretical Studies on the Characteristics of Atmospheric Pressure Glow Discharge with Liquid Cathode

Abstract

This study investigated the characteristics of an atmospheric pressure air-glow discharge with a liquid cathode. Distilled water was utilized as the cathode. The electric field strength, gas temperature as well as the emission intensity of some N 2 (C 3 u →B 3 g ) and OH (A 2 + →X 2 ) bands were measured at a discharge current ranging from 15 to 50 mA. Based upon the data obtained, the reduced electric field strength, E/N, and effective vibrational temperatures for N 2 (C 3 u , X 1 + g ) and OH (A 2 + ) were examined. The electron energy distribution function (EEDF) and some electron parameters (average energy, electron density and rate coefficients) were obtained based on a numerical solution of the Boltzmann kinetic equation. The result showed that the EEDF was not in equilibrium and the effective vibrational temperatures for N 2 (C 3 u , X 1 + g ) were essentially higher than the gas temperatures.

Spectroscopic Characterization of Miniaturized Atmospheric-Pressure dc Glow Discharge Generated in Contact with Flowing Small Size Liquid Cathode

“…The excited state of nitrogen, N 2 (C), was produced by electron impact excitation of nitrogen in the surrounding air. In contrast, a stepwise reaction consisting of the dissociation of molecular oxygen followed by electron impact excitation of oxygen atoms was probably the main mechanism responsible for producing excited states of atomic oxygen [13]. An alternative process, dissociative excitation of water by electron impact resulting in excited states of O, seems to be unlikely Fig.…”

“…require threshold energies of approximately *18 and *25-35 eV, respectively. Anyway, these values seem to be large compared with the energies of electrons or other high energy species present in glow discharge plasmas at atmospheric pressure [5,13].…”

“…Usually the generation of the APGD between a solid anode and a liquid cathode requires application of a dc high voltage [10][11][12][13][14]. Stable APGDs with liquid electrodes have been generated by applying voltages between 0.4 and 1.8 kV and currents between 5 and 150 mA, over gaps ranging from 0.2 to 5 mm in the air atmosphere [7,15,17,18].…”

“…Recently, APGD plasmas with various liquid electrodes have been studied at different currents and distances from the liquid electrode [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], while the other plasma generation parameters were faintly investigated. Nevertheless, the phenomena of glow discharge generated at atmospheric pressure are still poorly understood.…”

“…Additionally, Bruggeman et al [11] found that rotational temperatures of N 2 and OH were identical and equal to 3,250 K in the anode glow region (positive column). The cathode voltage drop, the electric field strength, and the vibrational and rotational temperatures of N 2 were studied by Titov et al [12,13] as a function of discharge current (10-50 mA) for distilled water and for aqueous solutions of HNO 3 , KCl, KBr and KI. The plasma parameters, i.e., the vibrational and rotational temperatures of N 2 (*4,200 and *2,100 K, respectively), indicated that this atmospheric pressure glow discharge was a non-equilibrium system.…”