(176b) Optical Design of Multi-Source High-Flux Solar Simulators

We present a systematic approach to design a class of high-flux solar simulators (HFSS) for solar thermal, thermochemical and materials research. The generic HFSS concept consists of an array of identical radiation modules arranged in concentric rows. Each module consists of a short-arc ion-discharge lamp coupled to a truncated ellipsoidal reflector. The positioning of the radiation modules is based on the overall rim angle of the system, the number of module rows, the number of modules in each row, the diameter of the reflector, and the required minimal spacing between the reflectors. Once the module array configuration has been fixed, the shape of the ellipsoidal reflector, i.e. its eccentricity and focal length, is determined such that it intercepts all radiation emitted by the light source. The radiative flux distribution generated by the array of radiation modules is calculated for selected flat and hemispherical control surfaces by applying the Monte Carlo ray-tracing method. The HFSS design is optimized for maximum radiative flux at the focal plane and to achieve acceptable flux distribution on the concave control surfaces behind the focal plane. For a 45 kW_e HFSS design with a 45° rim angle, consisting of 18 radiation modules arranged in two concentric rows, each consisting of a 50-cm diameter reflector and a 2.5 kW_e Xe short-arc lamp, the following characteristics at the focal plane are predicted: peak radiative flux of 11 MW/m²; total radiative power and radiation transfer efficiency of 15.4 kW and 81%, respectively. The radiative flux, radiative power and radiation transfer efficiency for a 30-mm diameter circular flat target at the focal plane are 7.5 MW/m², 5.3 kW, and 28%, respectively. For a 50-mm diameter circular flat target, the radiative flux, radiative power and radiation transfer efficiency are 5.0 MW/m², 9.8 kW, and 52%, respectively.