Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3–2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s−1. The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of ∼3 × 1015 cm−3 at 25 W. The maximum ozone production achieved by short-pulse excitation was ∼8.5 × 1015 cm−3 at 20 W, which was four times greater than that achieved by ac excitation at the same power level.