Subpixel Temperature Measurements in Plasma Jet Environments Using High-Speed Multispectral Pyrometry

Abstract

A high-speed (2 kHz) near-infrared (1.0–1.65 μm) multispectral pyrometer was used for noninvasive measurements of the subpixel temperature distribution near the sharp leading edge of a wing exposed to a supersonic plasma jet. The multispectral pyrometer operating in the field measurement mode was able to measure the spatial temperature distribution. Multiple spectra were used to determine the temperature distributions in the measurement region. The spatial resolution of the multispectral pyrometer was not restricted to one “pixel” but was extended to subpixel accuracy (the temperature distribution inside one pixel in the image space corresponding to the point region in the object space). Thus, this system gives high-speed, multichannel, and long working time spatial temperature measurements with a small data stream from high-speed multispectral pyrometers. The temperature distribution of the leading edge of a ceramic wing was investigated with the leading edge exposed to extreme convective heating from a high-enthalpy plasma flow. Simultaneous measurements with a multispectral pyrometer and an imaging pyrometer verify the measurement accuracy of the subpixel temperature distribution. Thus, this multispectral pyrometry can provide in situ noninvasive temperature diagnostics in supersonic plasma jet environments.