A spatiotemporal mapping of temperatures in an argon gliding discharge open to ambient air

We investigate a low-power (<100 W), low-flow (0.3 slm) argon planar gliding discharge (GD) open to ambient air using spatiotemporally resolved optical emission spectroscopy coupled with a collisional-radiative model to characterize electron and neutral gas temperatures under two discharge current conditions. At low current (≈0.05 A), the electron temperature reaches 1.7 ± 0.2 eV, while the neutral gas temperature remains at 810 ± 20 K, indicating a strongly non-equilibrium state. At higher current (≈0.5 A), the neutral gas temperature increases to 1280 ± 10 K, whereas the electron temperature remains nearly unchanged, revealing distinct energy coupling pathways for electrons and heavy species. Temporal scans of the electron temperature at fixed spatial positions along the discharge axis show little variation, while measurements near the cathode exhibit substantial variations (1.5–4 eV), indicating varying conditions within the near-cathode region. These results demonstrate that the present GD operates in a purely non-equilibrium regime and stress the importance of diagnostic platforms enabling localized, spatiotemporal characterizations.