Fast-Response Total Thermal Radiation Detectors

The construction, calibration, and performance of thin-film heat-transfer gauges in a measurement of the total radiant intensity of air at superorbital entry conditions are discussed. It is shown that reliance on an electrical bridge calibration alone can cause erroneous results. Magnetic interference from the shock tube flow was identified and eliminated by model design and shielding. Thin-film gauges are shown to be fundamentally unsuited for total radiation measurements because of noise caused by vacuum ultraviolet irradiation. Pyroelectric thermal detectors avoid this difficulty and offer several other advantages over thin-film gauges. The basic equations and practical considerations in the use of pyroelectric gauges are discussed.