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International audience; Raman spectroscopy is an efficient technique to study the irradiation damage in nuclear materials [1]. Indeed it is possible to investigate the microstructural modifications and to monitor the damage build-up. In order to observe the dynamic evolution of materials under irradiation, in situ Raman setup has been developed on the triple beam chamber of the JANNUS-Saclay irradiation facility. The sample evolution can thus be followed by Raman spectroscopy during single, dual or triple ion beams irradiation. Irradiation damages of several nuclear materials under single ion beam have already been investigated by in situ Raman at JANNUS facility UO2 as nuclear fuel [1-2], SiC [1,3] and Zircaloy as cladding materials [1] and B4C as neutron absorber [4]. It appears that Raman spectroscopy is a good technique to study on-line crystalline phase changes or amorphization of irradiated iono-covalent solids. Moreover, the use of dual ion beam irradiation coupled with in situ Raman has highlighted combined effects of nuclear (Sn) and electronic (Se) energy losses, which can induce additive damage production (as in ZrO2) or competitive recovery processes (as in SiC), in good agreement with Rutherford backscattering channelling (RBS/C) measurements [3].This paper will give a review of these results and present the new in situ Raman results for single and double ion beam irradiations. A particular emphasis will be given to the synergetic Se/Sn effects.[1] S. Miro et al., J. Raman Spectrosc., 45, 481 (2015).[2] C. Onofri et al., NIM B, 371, 51 (2016).[3] L. Thome et al., JAP, 117, 105901 (2015).[4] D. Gosset et al. JNM, 476, 198 (2016).

International audience; Raman spectroscopy is an efficient technique for studying the evolution of microstructure of materials under irradiation. For that purpose, a Raman spectrometer has been recently installed at the JANNUS-Saclay platform. In this paper, we describe the new setup for in situ experiments. These in situ experiments allowed following the microstructural evolution of different materials (SiC, ZrO2 and B4C) as a function of ion fluence on a single sample (either single crystal or polycrystalline ceramics) under the same irradiation conditions. Our results show that Raman spectroscopy is a versatile non-contact technique for studying on-line crystalline phase changes or amorphization of irradiated iono-covalent solids. A detailed analysis of Raman spectra is provided for the three materials (SiC, ZrO2 and B4C) investigated in this study, revealing quite different behaviors upon irradiation. Basically, Raman spectroscopy gives insight on these evolutions at the level of bonds given by specific phonon modes, in good agreement with Rutherford backscattering channeling (RBS/C), X-ray diffraction (XRD) or transmission electron microscopy (TEM) data, which provide information at a long-range scale. Copyright (c) 2015 John Wiley & Sons, Ltd.