Development and test of a high flux calorimeter at DLR Cologne

After an introduction into the principle of black body calorimeters the optical lay-out and the mechanical design of the DLR high flux calorimeter SUNCATCH are described. The various loss mechanism are evaluated and other important design parameter are discussed. In addition to constructional parameters the performance of the data acquisition system (DAS) highly influences the accuracy of the calorimeter. Main features of the DAS and the sensors are outlined. From a detailed error analysis of the SUNCATCH a measurement uncertainty of about +/-0.5% at high fluxes can be expected. A comprehensive measurement campaign with SUNCATCH, the flux mapping system FATMES and a Kendall radiometer under flux in the DLR solar furnace is described. An excellent agreement was found between both fluxmeter with an RMS deviation of about +/-1%.