Thermal model of an absolute solar radiometer designed for future satellite missions

This paper describes a finite-element thermal model of an absolute radiomet er designed for total solar irradiance (TSI) measurement in future satellit e missions. The cavity-type absolute radiometer employs the electrical-subs titution technique and active temperature control to determine the radiant power entering the receiving cavity. The nonequivalence between the shutter -open mode and shutter-closed mode due to different temperature distributio ns is a major factor that affects the radiometric accuracy. The analysis sh ows that the nonequivalence is a function of sensor positions and can be mi nimized by properly choosing the electrical heating method and the temperat ure sensor location.