Considering the evolution of microstructures and material properties under extreme radiation conditions, the JANNuS facility has been developed at University Paris-Saclay that allow multi-scale modelling of radiation effects in materials with in situ observations of microstructure modifications. The versatility of conditions in terms of particle energy, dose rate, fluence, etc., is a key asset of ion beams allowing fully instrumented analytical studies. Coupling of two or more beams, use of heated/cooled sample holders, and implementation of in situ characterization and microscopy pave the way to real time observation of microstructural and property evolution in various extreme radiation conditions more closely mimicking the nuclearenvironments.
Many promising applications in electronics, space, geologyare considered.