plasma system with rotational gliding arc between solid ... - ВАНТ

a)b b)aFig. 2. Current-voltage characteristics of discharge: stainless steel cathode (a), copper cathode (b) at various airflow rates (from 42 cm 3 /s to 417 cm 3 /s)The emission spectroscopy was used for plasma diagnostics.Emission spectra were registered by usage ofspectral device – spectrometer S-150-2-3648 USB. Thisspectrometer allows registering the emission spectra inthe wavelength range 200…1000 nm. Temperatures ofexcited electron levels population for various chemicalelements and their distribution along the plasma torchwere defined in dependence on the air flow rate valueand discharge current. This method is described in detailsin [9].Typical emission spectra of plasma in rotationalgliding arc discharge are shown in Fig. 3: stainless steelcathode (see Fig. 3,a); copper cathode (see Fig. 3,b).a a)b b)Fig. 3. Typical emission spectra of plasma in rotational gliding arc discharge with solid electrodes for stainlesssteel (a) and copper (b) cathode. G = 167 cm 3 /s; h = 0 mm; I = 340 mA; U = 0,8 kV214Spectra in both cases are mixtures, they containatomic lines, electrode materials Cr, Fe, and Cu multiplets,oxygen atoms O multiplets, and NO molecularbands. The temperatures of excited electron levels population(T e * ) plasma components such as Cr and O weredetermined from these spectra. Determination of temperaturesof excited electron levels population (T e * ) foroxygen atoms was carried by the Boltzmann diagrammethod using three most intense multiplets (777.2 nm,844 nm, 926 nm) and data from [3]. T * e of Cr atoms hasbeen determined by the ratio of the intensity of two intensemultiplets (357.9 nm and 425.4 nm) by usingcomparison of calculated and experimental spectra. Determinationof other components temperatures has beensignificantly more complex. It was caused by overlappingof their spectra.The plasma discharge was diagnosed at differentdischarge currents and along the plasma torch height(h). The range of air flow rate is 167…417 cm 3 /s. Thetemperature (T e * ) dependences on the current level werespecified for Cr and O atoms at different air flow ratesand stainless steel cathode. They are shown at Fig. 4.The error of T e * definition is near 500 K, so we can saythat the components temperature depends weakly fromcurrent.ISSN 1562-6016. ВАНТ. 2013. №4(86)