Abstract
Total Solar Irradiance (TSI) is the measure of the solar power per unit area, the electromagnetic radiation integrated over the whole electromagnetic spectrum at the top of the atmosphere, normalized to a distance from the Sun of 1 AU (astronomical unit). In order to measure TSI, solar radiometers are utilized.
In this work a study of the degradation process that solar radiometers suffer is presented. Among all sources that may produce damage on the receivers, this work is focused on UV radiation. Experimental data was obtained and compared against instruments who suffered degradation during their operative lifetime in space.
On the other hand, a next generation of receiver for solar radiometers was designed, studying changes on the coating (by application of the latest discoveries in ultra-black materials), the geometry of the detector (to improve the optical and mechanical properties of the new coatings), and the substitution of components of the instruments (by more recent technologies). The aim of this new generation of absolute radiometers is to obtain more accurate measurements avoiding degradation effects on their coatings. A prototype of this new receiver for solar radiometer was produced and optically characterized. The new coating provides a higher absorptance coefficient than the previous cavity design with glossy paints and no degradation due to UV radiation was found.
The Physikalisch- Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC) has a record of more than 100 years measuring the sun and a long history of developing radiometers. In 2015, an international team of experts placed the PMOD as one of two world-wide leading institutions in the field of Total Solar Irradiance (TSI) metrology. PMOD/WRC provides very high-quality services to international and national organizations such as the World Meteorological Organization (WMO) and space agencies, in particular the European Space Agency (ESA).
Remesal Oliva, Alberto