A Pyrometer Configuration for Measurement of the Temperature at the Rear Side of a TPS-Sample.

The heat flux into a TPS-sample exposed to a high enthalpy flow can only be determined by means of reliable measurements of its front and rear surface temperature development. The rear surface temperature of samples tested in the LBK has been estimated using the gas temperature measured by means of a thermocouple. Because of strong chemical interactions between the particles released from the sample rear surface and thermocouple the accuracy and reliability of the results have been limited. A new pyrometer configuration with miniature optics integrated into the sample holder and an optical fibre allow nonintrusive measurement of the sample rear surface temperature. After fabrication and calibration of the system comparative measurements have been carried out in an oven using all possible combinations of different optics with spectral and two color pyrometers. Problems noticed during the first test of the system in the LBK facility have been overcome due to a small modification of the new miniature optical system. All components have been qualified regarding their thermal resistivity at flow conditions whose corresponding surface temperatures are up to about 1400 Centigrades