Wenchun Wang

Density distribution of high energy electrons in pulsed corona discharge of NO+N2 mixture

Emission spectroscopy of the high-voltage pulsed positive corona discharge in a line-cylinder reactor is used to investigate the high-energy electron density distribution in the discharge gap. The relative overall emission intensity spatial distribution profile of the A2Sigma+ --> X2Pi transition of NO is successfully recorded against a severe electromagnetic pulse interference coming from the corona discharge at one atmosphere. The spectroscopic investigation shows that the high-energy electron density in the discharge has a nonlinearly decline in the radial distribution. When varying the discharge voltage, the absolute emission intensity of NO is different but the radial distribution profile is similar. If an oxygen flow was introduced into the discharge reactor, the emission intensity of NO decreases tremendously and, therefore, the high-energy electron density decreases reasonably.

Experimental investigation on large-area dielectric barrier discharge in atmospheric nitrogen and air assisted by the ultraviolet lamp.

In this paper, ultraviolet radiation produced by the ultraviolet lamp is employed to supply pre-ionization for the dielectric barrier discharge in N(2) or air at atmospheric pressure. The effect of the ultraviolet pre-ionization on improving the uniformity of the dielectric barrier discharge is investigated experimentally. The atmospheric pressure glow discharge of the large area (270 mm x 120 mm) is obtained successfully via the ultraviolet pre-ionization in atmospheric DBD in N(2) when the gas gap decrease to 3mm. Based on the emission spectra, the mechanism which ultraviolet pre-ionization improves the uniformity of the dielectric barrier discharge is discussed.

Stable and diffuse atmospheric pressure glow plasma in a multipoint-to-plane configuration in air

In a multipin-to-plate electrode configuration at negative polarity, a stable and diffuse atmospheric pressure glow discharge, controlled by fast airflow, was obtained. Electrical characteristics and still photos of the discharge were obtained. A mechanism of the discharge stabilization by fast airflow is discussed.

Spatially resolved spectra of excited particles in homogeneous dielectric barrier discharge in helium at atmospheric pressure

In this paper, the optical emission spectra of He (3s(3)S-->2p(3)P, 706.5 nm), OH (A(2)Sigma-->X(2)Pi, 0-0), N(2) (C(3)Pi(u)-->B(3)Pi(g), 0-0, 337.1 nm), and N(2)(+) (B(2)Sigma(u)(+)-->X(2)Sigma(g)(+), 0-0, 391.4 nm) emitted from plate-plate electrodes configuration homogeneous dielectric barrier discharge in helium are recorded at atmospheric pressure. The spatially resolved measurements are performed and the asymmetry discharge mode of homogeneous dielectric barrier discharge is observed with electrical and optical measurements when the micro-impurity (N(2), H(2)O) exists. The effects of applied voltage and driving frequency on the spatial distributions of the emission intensity of He (3s(3)S-->2p(3)P) are also investigated. It is found that the spatial distributions of the emission intensities of He (3s(3)S-->2p(3)P), OH (A(2)Sigma-->X(2)Pi, 0-0), N(2) (C(3)Pi(u)-->B(3)Pi(g), 0-0), and N(2)(+) (B(2)Sigma(u)(+)-->X(2)Sigma(g)(+), 0-0) exhibit two peaks at 1 and 6 mm from the upper electrode respectively in the 7 mm gas gap and the emission intensities at 1 and 6 mm are about two to three times higher than those at 3-4 mm; when micro-impurity (N(2), H(2)O) exists, the asymmetry discharge mode of homogeneous dielectric barrier discharge can be observed, the emission intensities at 6 mm are about 1.4 times higher than those at 1 mm. Also, the main involved physicochemical processes are discussed.