Laser-Induced Phosphorescence in Combustion Diagnostics: Calibration at Extremely High Temperatures

This paper describes essential results for thermographic phosphorescence applications in laser diagnostics at extremely high temperatures for reacting and non-reacting flows. Promising results have been attained although these applications perform poorly in hostile environments. An experiment was conducted to investigate the viability of non-contact temperature measurements based on thermographic phosphor in antagonistic conditions. A pulsed laser at 355 nm was used for phosphor excitation. This kind of excited luminescent emission is known as ‘LaserInduced Phosphorescence’ (LIP). The laser beam was applied to a sample of white phosphor powder at a laser power level (LPL) varying from 5 to 54 mJ/pulse in an area of 38.48 mm. The phosphor was dysprosium-erbium double-doped: yttrium aluminium garnet (Dy:Er:YAG). The sample was kept in an oven with temperatures ranging from room temperature up to 1800 °C. An adapted LIP Intensity-Ratio Temperature-Dependent (IR-TD) method was used for temperature assessments. This was validated by comparison with two different IR-TD methods. This investigation confirmed that temperature measurements are attainable in these environments given appropriate selection of the emission wavelength and temperature range.