Changes in the Optical Properties under Sequential and Separate Irradiation with Solar Spectrum and Protons of a BaSO₄ Powder Modified with SiO₂ Nanoparticles

Abstract

A comparative analysis of changes in the diffuse reflectance spectra ρλ and the integral absorption coefficient in the region of 0.2–2.2 μm after separate and sequential irradiation with 5 keV protons and solar radiation quanta of a barium sulfate powder modified with silicon dioxide nanoparticles mBaSO4/nSiO2 was performed with registration of the spectra after each period of irradiation in vacuum in the area of irradiation (in situ). The integrated solar radiation absorption coefficient of the modified mBaSO4/nSiO2 pigment before irradiation is 0.048, which is several times lower than that of the ZnO pigment widely used in all countries. It has been found that the additivity coefficient calculated from the results of sequential and separate irradiation of the mBaSO4/nSiO2 powder decreases from 7.5 to 1.052 times with an increase in the fluence of protons with an energy of 5 keV. An assessment of the changes in the additivity coefficient under the influence of the spectrum of charged particles in the geostationary orbit (as one of the most used and with harsh radiation conditions) showed that the non-additivity of the separate and sequential action of protons and solar radiation quanta on the pigment for thermal control coatings mBaSO4/nSiO2 at such irradiation parameters will be kept for 1.27 years.