On the use of the intensity ratio of He lines for electric field measurements in atmospheric pressure dielectric barrier discharge

Application of Y–ZrO2 microtubes as dielectric barrier material in a He atmospheric pressure micro-plasma jet

“…Both He line ratios (587/706 nm and 667/728 nm) have been used as an indicator for the electric field strength [39,40]. Furthermore, Ivkovic et al developed a collisional radiative model for the calculation of the 667/728 nm line ratio as a function of electric field strength and for electric field strength in the range of 3-40 kV/cm [40]. They further validated the model by using Stark polarization spectroscopy in a dielectric barrier discharge.…”

“…They further validated the model by using Stark polarization spectroscopy in a dielectric barrier discharge. The analytical formula proposed in that work has the form E(kV/cm −1 ) = 2.2 24-20.18•R + 45.07•R 2 -19.98•R 3 + 3.369•R 4 [40], where R is the 667/728 nm line intensity ratio. In our case, the use of this formula results in electrical field values of several hundred kV/cm which is outside the electric field range which was used to obtain the analytical formula.…”

“…This can affect the gas purity near the tube orifice as a result of back-diffusion of air impurities. Air impurities create additional loss channels for 3 1 D and 3 1 S excited states of He which were not taken into account in the model by Ivkovic et al and were used for E/N determination from the He 667/728 line ratio [40]. Nonetheless, between positions 1 and 6 mm the 667/728 nm line ratio remained constant, and the effect of impurities is expectedly negligible.…”

“…Y-ZrO 2 or YSZ is a material, where yttria is required to stabilize zirconia at room temperature in the tetragonal/ cubic phase. YSZ has high dielectric constant (32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42) [31], refractive index (2.15-2.2) [32,33] excellent mechanical properties and fracture toughness, chemical resistance and biocompatibility. Due to those properties, YSZ is a very important engineering material that has found use in various fields ranging from dentistry [34] to metallurgy [35].…”

“…Optical emission spectra were registered along the axis of the YSZ microtube, and spatio-temporal evolution of the ionization wave in the YSZ microtube was determined. Several line ratios were identified to characterize trends in excited species concentrations and changes in the electric field strength according to several experimental and theoretical works [39,40]. The line ratios were compared with measurements in quartz tubes of similar diameters to identify the effect of the tube material.…”