The influence of spatial arrangement of endpoints on output characteristics of ITO/In2O3 heat flux gauge

[Display omitted] •The thin film heat flux gauge employs thermopile based on ITO and In2O3.•The spatial arrangement position of endpoints is investigated on the output the characteristics of heat flux gauge.•The steady-state and the transient response characteristics of the heat flux gauge were also investigated. Thermopile is a common test structure, in which the distribution of hot and cold endpoints has a high impact on its performance especially for applications in thin-film heat flux gauge. In this work, the influence of spatial distribution of endpoints is investigated on the output characteristics of the thin film heat flux gauge based on ITO/In2O3 thermopile. Three different structures of the heat flux gauges, which are horizontal, vertical and stepped, are designed and fabricated via sputtering according to different spatial arrangement of endpoints. The results show that the heat flux gauges based on vertical distributed structures have higher sensitivities than the gauges based on the other two structures on a convection heat source calibration platform. The output sensitivities of the gauges based on stepped distributed structure is the highest on laser radiation calibration platform, which reach 74.9 μV/(kW/m2). The thin-film heat flux gauge based on horizontal distribution structure has the best dynamic characteristic on a laser heat source calibration system. The operating temperature of the gauge is close to 800 °C, and the dynamic frequency reaches 5.2 kHz.