Experimental Study of Current-Voltage Characteristics and Optical Emission of Various Gases in Dielectric Barrier Discharge at Atmospheric Pressure

Abstract

© 2012 Published by Elsevier B.V. This study reports experimental investigations of current-voltage characteristics and optical emission from argon, helium, nitrogen, and air plasma generated by 17-kHz dielectric barrier discharge at atmospheric pressure. The plasma reactor is custommade with (i) an electrode diameter of 9.6 cm and gap between electrodes of 0.3 cm (ii) dielectric materials of 4.8 in dielectric constant and 0.2 cm in thickness. The plasma reactor has been modeled as a capacitance from dielectric barriers in series with a capacitance from working gas in parallel to variable impedance from the discharging plasma. External 50-Ω resistor and 0.1-μF capacitor were coupled to the reactor for measuring total current and total charge transfer, respectively. The discharge current is obtained from subtracting the measured current with the stray-capacitive and the gaseous-capacitive current. The charge over the external 0.1-μF capacitor and the applied voltage were used to plot Lissajous figures. From such a figure, it is observed that helium starts the first discharge of a few μs in its characteristic time at 2 kV p-p , then the second discharge of a few ten μs at 4 kV pp . The former discharge is understood as glow-like discharge while the latter discharge as Townsend-like one. In 2-6 kV p-p range, four discharge peaks were observed in total. Argon has their first discharge at higher voltage of about 5 kV p-p . Nitrogen and air plasma were much more difficult to discharge. They do not glow in the voltage range of up to 17 kV p-p but rather show filamentary discharge instead. The optical emission confirms the characteristic spectral lines of each gas; however, it could not differentiate the glow-like discharge from the Townsend-like one.