Nanosecond Discharges as a Tool for Measuring Energy Efficiency (<i>g</i>-values) at High Reduced Electric Fields Based on Nitrogen Dissociation

The production of reactive species in nanosecond, repetitively pulsed plasmas is of decisive importance in tailoring such discharges to different applications. In this paper, we examine the features and advantages of using a nanosecond discharge at moderate pressure as a tool for measuring the G-value. The N-atom production in a pure N2, nanosecond pulsed plasma at a moderate pressure of 20 mbar and high reduced electric field of 180 +/- 20 Td is adopted as the test case. The atomic nitrogen density is measured using two-photon absorption laser-induced fluorescence (TALIF). A principal objective of this work is to compare the resulting G-value with those of other authors at lower electric fields and with our previous paper measuring G-values at the same reduced electric fields but higher specific energy deposition (SED). The spatially non-uniform profile of plasma in the present work, which displays a minimum at the center, necessitates the conception and implementation of an in-house, Abel inversion algorithm to accurately reconstruct the radial profile. This in turn permits a more accurate determination of the nitrogen dissociation in the entire tube, thereby achieving good agreement with kinetic simulations. Taken together, these results conclusively demonstrate the advantages of using pulsed nanosecond discharges at moderate pressures for studying the energy efficiency of dissociation processes at high E/N.