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

Abstract

This work reports average electron temperature (Te) and electron density (ne) of an atmospheric argon rotating gliding arc (RGA), operated in glow-type mode, under transitional and turbulent flows. Both Te and ne were calculated near the shortest (δ) and longest (Δ) gap between the electrodes, by two different methods using two separate measurements: (1) optical emission spectroscopy (OES) and (2) physical–electrical. Te calculated from (a) collisional radiative model (CRM) (OES) and (b) BOLSIG+ [physical–electrical, reduced electric field (ENo) as input], differed each other by 16%–26% at δ and 6% at Δ. Te was maximum at δ (>2 eV) and minimum near Δ (1.6–1.7 eV). Similarly, the ENo was maximum near the δ (5–8 Td) and minimum near Δ, reaching an asymptotic value (1 Td). By benchmarking Te from CRM, the expected ENo near δ 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 ne near δ and Δ from Stark broadening (OES) was 4.8–8.0×1021 m−3, which is an order higher than the ne calculated through current density (physical–electrical). Te and ne 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 RGAs (fine-structure resolved), (b) the poly-diagnostic approach to estimate plasma parameters, and (c) the validation of ENo calculated using physical–electrical measurements.

Effect of gas flow rate on breakdown voltage in a rotating gliding arc reactor

“…Rotating gliding arc discharges have been extensively studied for its chemical applications [1,2]. The working principle of RGAs is similar to that of conventional gliding arc discharges (GAD) made of planar diverging electrodes i.e., an arc strikes at the shortest gap between the electrodes when sufficient electric field is given to create breakdown; after initial breakdown, the arc is pushed by the gas downstream thereby elongating the arc [3].…”

“…As mentioned earlier, once the arc is initiated due to breakdown, it is rotated by the gas vortex and elongated by the geometrical orientation of the electrodes during its rotation (see 3D view in figure 1). Further details on reactor and working of electrode configuration can be seen in earlier work of authors [1,4,5]. The discussion in this work is limited to the breakdown voltage without discussing the rotation of the arc in this RGA.…”