SOLAR RADIATION SIMULATION STUDIES, PART 2

Studies and tests performed to establish the feasibility of solar simulation systems for an environmental chamber are reported. Performance objectives for the chamber and other solar simulator systems are delineated and compared. Tests were initiated on several short-arc lamps including the 10-kw xenon lamp, the 2.5-kw xenon mercury lamp and the fluid-transpiration arc source. The spectral energy distribution, radiant efficiency, polar diagram, intensity and uniformity as well as size and shape of the radiating medium under several conditions for each radiant source are examined. The influence of quartz envelope adsorption, envelope blackening, optical system reflectivities, detector fatigue, and standard source calibration is under evaluation. A reference module optical system concept based upon three and one half on-axis reflectors is examined. Ray tracing techniques are applied to determine the collimation and uniformity obtainable with an ideal short-arc source, and optical efficiencies of the several components are examined. Preliminary studies of the stability of simulator materials in the nuclear radiation environment of the chamber are also reported. In addition, the multiple source concept supplying a single collimator and the problems associated with refracting vs reflecting elements are analyzed.