Comparison of discharge mode transition of air plasma under pulsed and sinusoidal excitations

Abstract

The transition from O3 to NOx discharge mode is common for air plasma with an increase of discharge power density, which greatly changes the chemistry of the plasma as well as its application effect. Although this discharge mode transition has been intensively studied in recent years, differences between plasmas subject to pulsed or sinusoidal excitations have rarely been reported on. In this study, a surface dielectric barrier discharge is excited using either a microsecond pulsed voltage or a sinusoidal voltage. The discharge mode transition of these two excitations is then comparatively studied. The results indicate that pulsed excitation produces more O3 in O3 mode discharge; the O3 concentration for pulsed excitation is 27.7% higher than that for sinusoidal excitation at the same power density of P = 0.08 W/cm2. On the contrary, it produces less NO and NO2 in NOx mode discharge; the NO concentration for pulsed excitation is 13.2% lower than that for sinusoidal excitation at P = 0.32 W/cm2. As a result, pulsed excitation delays the transition of the discharge mode when the discharge power density increases. This can be attributed to the higher electron and lower gas temperature of the pulse-excited plasma, which promotes O3 and inhibits NOx production.

The effect of bending angle on a flexible electrode DBD plasma under sinusoidal excitation

“…The intensity of all bands decreased at 4.8 kV. This is easy to understand since higher intensity of discharge results in a higher emission intensity [28]. No emission lines of O, OH, and hydrogen atoms were observed due to low concentration of H 2 O in the air.…”

“…The 180 • configuration demonstrated a similar trend of discharge intensity with an area of low intensity clearly seen in the top view. The white color in both bending configurations suggested that the discharge intensity was much higher in that area [28]. By analyzing the image brightness and spatial distribution status, the distribution of discharge images is shown in figure 4 for the two voltages of 4.8 and 5.4 kV for the three configurations studied.…”

“…The numbers in the scale bar (0-6000) represent the relative intensity of the color bar, which is proportional to the relative luminous intensity of the plasma. The plasma is produced in both positive and negative half cycles [28]. The maximum of light emission is reached at a time of 42 µs.…”