Estimation of electron density and temperature in an argon rotating gliding arc using optical and electrical measurements

Abstract

This work reports average electron temperature ($T_e$ ) and electron density ($n_e$ ) of an atmospheric argon rotating gliding arc ($RGA$ ), operated in glow-type mode, under transitional and turbulent flows. Both $T_e$ and $n_e$ were calculated near the shortest ($\delta$ ) and longest ($\mathrm{\Delta }$ ) gap between the electrodes, by two different methods using two separate measurements: (1) optical emission spectroscopy ($OES$ ) and (2) physical–electrical. $T_e$ calculated from (a) collisional radiative model ($CRM$ ) ($OES$ ) and (b) BOLSIG+ [physical–electrical, reduced electric field $(\frac{E}{N_o})$ as input], differed each other by 16%–26% at $\delta$ and 6% at $\mathrm{\Delta }$ . $T_e$ was maximum at $\delta$ ($>2$ eV) and minimum near $\mathrm{\Delta }$ (1.6–1.7 eV). Similarly, the $\frac{E}{N_o}$ was maximum near the $\delta$ (5–8 Td) and minimum near $\mathrm{\Delta }$ , reaching an asymptotic value (1 Td). By benchmarking $T_e$ from $CRM$ , the expected $\frac{E}{N_o}$ near $\delta$ was corrected to 3 Td. The calculated $CRM$ intensity agreed well with that of the measured for most of the emission lines indicating a well optimized model. The average $n_e$ near $\delta$ and $\mathrm{\Delta }$ from Stark broadening ($OES$ ) was 4.8–$8.0\times {10}^{21}$ ${\mathrm{m}}^{-3}$ , which is an order higher than the $n_e$ calculated through current density (physical–electrical). $T_e$ and $n_e$ were not affected by gas flow, attributed to the glow-type mode operation. To the best of authors’ knowledge, this work reports for the first time (a) an optimized $CRM$ for $RGA$ s (fine-structure resolved), (b) the poly-diagnostic approach to estimate plasma parameters, and (c) the validation of $\frac{E}{N_o}$ calculated using physical–electrical measurements.