6WIND (France)

The micro-structure, residual stresses, and micro-distortions generated near the surface in the AA6061-B4C metal matrix composite by glass-bead blasting are investigated and compared with those of the bulk. In contrast to the bulk, the sublayer is under compression and contains an extremely low density of B4C and a high density of dislocations. Corrosion behaviour was studied in H3BO3 after immersion at the OCP and after accelerated tests. In the sublayer, initial rapid oxidation (formation of a homogeneous oxide film) is followed by slow oxidation (average corrosion rate: 2 µm/year); the oxidation front moves parallel to the surface. In the bulk, oxidation takes place along preferential paths defined by the distribution of B4C. The driving force is the galvanic coupling between B4C and the matrix. Once corrosion proceeds, corrosion products (oxidation of the sublayer) become weakly adherent, peeling off locally. The bulk is then directly exposed to the solution, promoting corrosion.

Precise and predictable propagation and deposition of laser energy in high energy density (HED) plasma is threatened by the breakup of the beam into filaments. Such filaments can be deflected and sprayed but also locally intensify the light, increasing the likelihood of other problematic interactions with the plasma. Adequately modeling, anticipating, and avoiding such processes in HED experiments requires a thorough understanding of the thresholds and nonlinear saturation mechanisms, particularly for the weakly collisional, high temperature plasmas achieved at the National Ignition Facility (NIF).

The growing need for producing renewable energy such as photovoltaic electricity, and the mitigation of the increasing occurrences of heatwaves and drought affecting annual crops, could be addressed by the installation of agrivoltaic systems. Depending on pedoclimatic context, cultivated crop, solar panels technology and implementation configuration, solar panels shading can improve or reduce crop growth and yields. Among photovoltaic installations, solar trackers might have a high development potential. These photovoltaic panels are mounted on a vertical axis at a 7m height. Thanks to their height, their biaxial moving capacity, their small anchoring surface and their punctual structure making plants design easily adaptable to agricultural constraints, they can fit with all types of agricultural systems. The aim of this study was to evaluate the impact of such trackers on crop growth and yields. For this purpose, a set of 6 different fields crop located in western France were studied. Crop phenology, height and yield were investigated. Results showed a delay in crop development near the trackers that was overcome late in the crop cycle, near harvest. For crop height and crop yield, the results showed important spatial variability but without clear trend related to the tracker shadow. The results are discussed in the light of new perspectives, including the consideration of microclimatic and pedological data to better explore the effects of trackers on plant growth and development, the measurement of morphological and physiological traits of plants, the accounting of a multi-trackers effect implemented on the same site, the temporal dynamics of the effect of a tracker.