Effect of pre-charging to plasma reactor on repetitive barrier discharges produced by reciprocal traveling wave voltage pulse

This paper describes an experimental study for NO_x decomposition using repetitive streamer discharges produced by reciprocal traveling wave voltage pulse from a direct-grounded coaxial cable. When the cable is charged and then grounded at one end of the cable without any resistance, a reciprocal traveling voltage pulse is repeatedly applied to a barrier-type reactor at the opposite end with a change in its polarity. High-speed photographs of discharge light indicated that the voltage oscillation caused by one switching induced alternate propagation of positive and negative streamers with a very high frequency. The 50% streamer initiation voltage with the reciprocal pulse generator was much smaller than that with a single pulse generator having a matching resistance. The reason for the difference in the 50% voltage was explained by the effect of pre-charging to the dielectric barrier. In the case of the reciprocal pulse, a large number of space charges were accumulated on the barrier surface during the cable charging, so that the field strength in the gap was strongly enhanced after the polarity reversal. In the test of NO removal from a flue gas, high NO removal ratio was obtained under the low applied voltage when the reciprocal pulse generator was used. Removal weight of NO per unit discharge energy in the reciprocal pulse generator was lower than that in the single pulse generator. However, the total efficiency calculated with the stored energy in the reciprocal pulse generator gave a better performance.