Two-dimensional temperature measurement method with line and continuum emissions in Ar–N₂ DC arc for wide temperature range

Abstract This study introduces a method for highly accurate temperature measurement of thermal plasmas with a high-speed camera. Previously reported method enabled precision measurement of temperatures between 17 000 and 30 000 K using only monochromatic intensity at the wavelengths of ionic line spectra. The new approach employs a relative intensity with consideration of line and continuum emissions. This paper achieves two improvements: visualization of a wide temperature range between 10 000 and 30 000 K, and high accuracy of Abel inversion. The wide temperature range can be visualized more accurately by combining wavelengths of atomic and ionic line spectra. Temperature is calculated mainly by the ratio of the line spectra to the continuum emissions. Regularization was applied to Abel inversion to improve the reliability of temperature measurements. Abel inversion with regularization reduces noise by one order of magnitude compared to Abel inversion with smoothing.