Nonheating ozone suppression in pulsed air discharges: role of pulse duration and repetition rate

Abstract

Facilitating the separate production of ozone (O3) and nitrogen oxides (NO x ) in air discharges without a thermal process is of most merit in diversifying plasma technology; in particular, it is a primary requirement in certain cold, heat-sensitive plasma applications. Here, we propose a new method of nonheating ozone suppression in air discharges. The present work demonstrates that controlling the plasma chemical kinetics by adjusting the duration (width) and/or repetition frequency of the high-voltage DC pulse is effective in suppressing ozone formation in a surface dielectric barrier discharge in static ambient air. The temporal development of each oxygen- and nitrogen-related species in air discharge is complicated and shows different trends in the time range <10 µs; relatively long-lived O3 and NO x are strongly governed by the temporal behavior of short-lived reactive species, such as excited N2(A) and N2(v). To quantify time-varying O3 and NO x , an in situ UV absorption spectroscopy is applied to our gas-tight plasma reactor, which is operated in air at 21 °C. With a fixed frequency at 10 kHz and decreasing pulse duration from 10 μs to 0.18 μs, ozone is quenched faster in the plasma reactor, resulting in an irreversible chemical mode transition from an O3- to NO-rich environment. From a different set of experiment (with a 200 ns pulse duration and a frequency range of 1–10 kHz), we can conclude that the off-pulse period also plays a crucial role in the temporal evolution of O3 and NO x ; the larger the applied driving frequency is, the earlier the ozone-free phenomenon appears over the discharge time. Our findings represent a breakthrough in expanding the usage of air discharges and their application in various fields of interest.

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

“…Our experimental results highlight that pulsed excitation can lead to the discharge mode transition, just as sinusoidal excitation does. This is in agreement with the results of Park et al [21].…”

“…Yuan et al investigated the differences in O 3 production yield under pulsed voltage for four types of polarities [20]. More recently, Park et al studied the impact of pulse duration and frequency on O 3 quenching [21]. Pulse-excited plasma is usually more effective than sine-excited plasma because more energy is used for electron acceleration than heating, so the electron temperature is relatively high while the gas temperature is relatively low [22][23][24].…”

Effect of Atmospheric-Pressure Plasma on Functional Compounds and Physiological Activities in Peanut Shells

“…A spectroscopic chemical analysis was also performed for NO x 150 °C, although the results are not shown here. In this case, NOx was the dominant species during the entire period in both reactors because the chemical transfer to the second reactor started after the plasma reactor was completely free of O 3 [ 23 ].…”

The 2022 Plasma Roadmap: low temperature plasma science and technology

“…Increasing the efficiency of ozone generation in both smalland large-scale plasma reactors has been an ongoing research effort. Both models and experiments have been used to optimize the operation of dielectric barrier discharge (DBD) reactors for ozone production including the electrode geometry, dielectric properties, operating pressure, gas temperature, and power modulation [157,158]. Ozone production efficiency is also strongly dependent on the purity of the starting O 2 .…”