Concentrated solar energy as a diagnostic tool to study materials under extreme conditions

This paper deals with the material testing under extreme conditions, mainly around space programs, using the French CNRS (Centre National de la Recherche Scientifique) solar facilities for planetary entry (Earth, Mars), solar corona in situ exploration, and cryogenic propulsion. For these purposes, different facilities were developed around the various solar concentrators: MESOX (Moyen d'Essai Solaire d'OXydation), for the study of the atomic oxygen recombination at the surface of heated materials and the oxidation kinetics of ceramics under plasma atmospheres up to 2300 K. (Some results are given for several materials.); MEDIASE (Moyen d'Essai et de DIagnostic en Ambiance Spatiale Extreme), for the thermophysical characterization of thermal shield materials up to 2400degreesK under high vacuum: mass-loss kinetics, mass spectrometry (neutral and ionic species) and thermo-radiative properties (total or spectral directional emissivity). (Results are presented for various carbon/carbon composite materials.); and DISCO (DISpositif de Caracteisation Optique), for the measurement of changes in the reflectivity of materials at temperatures up to 2500degreesK and its correlation with the surface behavior (aging, ablation and oxidation). Results concerning a copper alloy used for the combustion chamber of cryogenic motors are given.