Small-size spectrometer for emission analysis of low-temperature plasma flows

Determination of temperature in a plasma jet emanating from a plasma torch with sectioned inter-electrode insert from the molecular emission spectrum of nitrogen

“…Spectral measurements were performed using a compact multi-channel spectrometer with concave holographic grating [1]. The average density of grooves in the gratings was 1200 mm −1 .…”

“…The plasma jet was generated by a dc electric-arc plasma torch with rated electric power 50 kW [1]. In the plasma torch, the gas-discharge chamber was a channel diverging from cathode to anode and presenting an assembly of several IEI sections electrically insulated from each other and from the electrodes.…”

“…With known range of the electron temperature T e of the plasma, we can evaluate the range of α using the Saha equation, which relates the concentrations [N 2 ] and [N 2 + ], the electron concentration n e , and electron temperature T e . Figure 5 shows the total emission spectrum for T v = T r = 6000 K and α = 1; indicated in the figure are the characteristic spectral lines that were subsequently used in identification and treatment of the spectra, namely, the cants of the bands (0,0) and (1,0) of the N 2 + system resolved from the long-wave side and the intensity maxima of the band heads (0,1) of N 2 and (2,1) of N 2 + .…”

“…The purpose of the present study was to determine the distribution of temperature in a no-current nitrogen plasma jet discharged to atmosphere from a dc plasma torch based on the molecular emission spectra of nitrogen registered using a compact multichannel spectrometer [1].…”

“…In [1], for measuring the temperature in an air plasma jet emanating from a plasma torch with sectioned inter-electrode insert (IEI), emission lines due to Cu(I) copper atoms present in the jet flow owing to copper-anode erosion were employed. With nitrogen used as the plasma-forming gas, the erosion turns out to be one order of magnitude supressed and, as a result, the emission intensity in the lines due to copper atoms becomes too weak for performing temperature measurements.…”