The influence of carrier gas on plasma properties and hydrogen peroxide production in a nanosecond pulsed plasma discharge generated in a water-film plasma reactor

The influence of carrier gas (argon and helium) on the properties of a nanosecond pulsed filamentary discharge propagating along the water surface in a water film plasma reactor, and the effects of plasma properties on the formation of hydrogen peroxide (H2O2) are investigated. The plasma properties, including electron density, gas temperature, and plasma volume, and the hydrogen peroxide production rate and energy yield were measured and compared in both argon and helium discharges. The results show that helium plasma is more diffusive compared with the argon plasma, and it has lower electron density and gas temperature but larger volume. The production rates and energy yields of hydrogen peroxide are only slightly higher in the helium plasma although the electron density is much lower. A simple mathematical model with time-dependent fast radical and electron quenching in a small film surrounding the plasma core and with lumped reaction kinetics for H2O2 formation and degradation suggests that the hydroxyl radical (center dot OH) concentration is approximately two times higher in the argon discharge, but the larger volume of the helium leads to about two times more total center dot OH in the helium with correspondingly higher energy yields. The experimental data and model imply that the H2O2 energy yield may increase at lower power (or specific energy density) for both carrier gases.