A High-Temperature Heat Flux Sensor Using the Transverse Seebeck Effect in Elemental Rhenium

Heat flux sensors compatible with hot environments are critical to advance aerospace, materials, and energy generation technologies that cope with extreme thermal conditions. In this work, we report on the development and characterization of a high-temperature heat flux sensor using the transverse Seebeck effect in rhenium single crystals.  The sensor leverages refractory alloys and ceramics compatible with temperatures exceeding 1000°C.  The heat flux sensor was characterized from room temperature to 500°C using a temperature-controlled calibration facility. At constant temperature, the sensor’s voltage output is linear with respect to the absorbed heat flux.  The responsivity of the sensor varies with temperature, from 1.3 V/(W/cm) at room temperature to −3.2 V/(W/cm) at 500°C, increasing monotonically in magnitude after changing sign from positive to negative at approximately 300°C.  The experimental results are in good agreement with analytical predictions of the sensor’s temperature-dependent responsivity, which suggest a further increase in magnitude up to −7.4 V/(W/cm) at 1000°C.  These results highlight the unique characteristics of rhenium as a TSE transducer.  The design offers compatibility with a wide range of operating temperatures and yields a measurement sensitivity that increases as the environmental conditions become more challenging.