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International audience; The temporal and spatial evolution of dispersed media is a fundamental problem in a widerange of physicochemical systems, such as emulsions, suspensions or aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore subject to the influence of gravity which determines the sedimentation rate of their dispersed phase. This effect can be dominant and prevent a detailed study of the phenomena occurring between the constituents themselves, such as the coalescence of drops in emulsions, the evaporation of droplets or the flocculation in suspensions. In this context, the Centre National d'Etudes Spatiales (CNES) has recently supported the development of a new instrument to produce populations of droplets, a few micrometers in radius, under controlled conditions with the objective of allowing a detailed study of their properties in microgravity conditions. The principle of this instrument is to generate, by a fast compression/expansion of air, populations of water droplets and to track their evolution by optical scanning tomography in transmission mode within a volume of approximately 2 mm3. Parabolic flight experiments have shown the possibility to generate and accurately follow the evolution of populations of several hundred droplets for more than 20 seconds. The first experimental results show that it is possible to study their evaporation kinetics or their motion when imposing Von Karman swirling flows to air. This work is part of the AEROSOL project of DECLIC-EVO supported by CNES and aims to help the understanding of cloud microphysics which remains a critical open problem in the context of global warming.

International audience; The temporal and spatial evolution of dispersed media is a fundamental problem in a wide range of physico-chemical systems, such as emulsions, suspensions or aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore sensitive to buoyancy which determine s the rate of sedimentation of the dispersed phase . The latter usually prevent s a detailed study of the phenomena occurring between the constituents of aerosols , such as coalescence and evaporation of drops or flocculation of fine particles . The idea of this work is to generate with a fast compression/expansion of air, populations of water drop let s and to track their evolution by optical scanning tomography in transmission mode. Parabolic flights experiments have shown the possibility to generate and accurately follow the evolution of several hundred droplets for more than 20 seconds of microgravity within a 2 mm 3 volume . First results show that it is possible to study their evaporation kinetics as well as their motion when moving in a Von Karman swirling flow. This work is part of the AEROSOL project of DECLIC EVO supported by CNES and aims to help the understanding of cloud microphysics which remains a critical open problem in the context of global warming.

International audience; Aerosols are divided systems in which liquid and/or solid particles evolve in a continuous gas phase. They are naturally subject to the influence of gravity, which determines the settling speed of the particles they contain. Aerosols have many applications in the pharmaceutical and cosmetic industries (inhalers, sprays), in metallurgy (spray drying) and in agriculture (pesticides). From an academic point of view, they are the subject of intense research activity. The description of their evolution is, for example, a major issue in climatology. With global warming, more water is evaporatingin the air resulting in more cloud formation and a higher importance of cloud microphysics in the understanding of the climate evolution. In this context, CNES has recently supported the development of a new instrument allowing not only to produce aerosols under controlled thermodynamicconditions but also to follow their evolution in microgravity. This work presents results of parabolic flight experiments. It demonstrates the possibility of producing aerosols and to investigate their properties with optical microscopy for periods of about twenty seconds.