This project aims implement a complete modeling of the hydrogen blistering phenomenon in metals, accounting for every process stages: vacancy diffusion & clustering; bubble formation; bubbles growth, cracking. This model will be applied to two model materials for mechanical and fusion communities: iron and tungsten.

The present project is put into the context of the international projects ITER and DEMO aiming at managing nuclear fusion to produce energy. In tokamaks (nuclear fusion reactors), a hot plasma composed of deuterium and tritium nuclei is magnetically confined to achieve fusion. The heating of the plasma is mainly obtained by the injection of high-energy deuterium neutral beams, coming from the neutralization of high-intensity D- negative-ion beams. D- negative-ions are produced in a low-pressure plasma source and subsequently extracted and accelerated. The standard and most efficient solution to produce high negative-ion current uses cesium (Cs) injection and deposition inside the source to enhance negative-ion surface-production mechanisms. However, ITER and DEMO requirements in terms of extracted current push this technology to its limits. The already identified drawbacks of cesium injection are becoming real technological and scientific bottlenecks, and alternative solutions to produce negative-ions would be highly valuable. The first objective of the present project is to find an alternative solution to produce high yields of H-/D- negative-ions on surfaces in Cs-free H2/D2 plasmas. The proposed study is based on a physical effect discovered at PIIM in collaboration with LSPM, namely the enhancement of negative-ion yield on boron-doped-diamond at high temperature. The yield increase observed places diamond material as the most up to date relevant alternative solution for the generation of negative-ions in Cs-free plasmas. The project aims at fully characterizing and evaluating the relevance and the capabilities of diamond films (intrinsic and doped polycrystalline, single crystal as well as nanodiamond films…) as negative-ion enhancers in a negative-ion source. The second objective is to investigate diamond erosion under hydrogen (deuterium) plasma irradiation, with two main motivations. First, material erosion could be a limitation of the use of diamond as a negative-ion enhancer in a negative-ion source and must be evaluated. Second, the inner-parts of the tokamaks receiving the highest flux of particles and power are supposed to be made of tungsten, but its self-sputtering and its melting under high thermal loads are still major issues limiting its use. It has been shown in the past by one of the partners that diamond is a serious candidate as an efficient alternative-material for fusion reactors. Therefore, diamond erosion in hydrogen plasmas will also be investigated from this perspective. At the moment when all the efforts are put on tungsten, maintaining a scientific watch on backup solutions for tokamak materials is crucial. The project associates partners with complementary expertise in the field of plasma-surface interactions on the one hand, and diamond deposition and characterization on the other hand. Furthermore, in order to span the gap between fundamental science and real-life applications, negative-ion surface-production and diamond erosion will be studied in laboratory plasmas (PIIM in collaboration with LSPM ) as well as in real devices (Cybele negative-ion source at IRFM and Magnum-PSI experiment at DIFFER ). PIIM: Physique des Interactions Ioniques et Moléculaires, Université Aix-Marseille, CNRS LSPM: Laboratoire des Sciences des Procédés et des Matériaux, CNRS, Université de Paris 13 IRFM: Institut de Recherche sur la Fusion Magnétique, Commissariat à l’Energie Atomique, Cadarache DIFFER: Dutch Institute For Fundamental Energy Research, The Netherlands

This project focuses on the elaboration of a composite material presenting new functionalities, thanks to its innovative chemical composition and structure, which will allow tuning its magnetic properties by the application of an electric field. We will sinter new composites artificially coupling together an inorganic piezoelectric matrix with unidimentional ferromagnetic nano-inclusions. The use of lead-free piezoelectric compounds and rare earth-free magnets is proactive in relation with the current legislation. A new, low-cost and eco-friendly elaboration process will be developed. In particular the uniqueness of our project consists in using the Spark Plasma Sintering technique assisted by a magnetic field allowing the control of the magnetic nano-inclusions organization within the piezoelectric matrix. The final goal will be the optimization of the Magneto-Electric coupling properties. These properties will be studied as function of the micro and nanostructure and the quality of the interfaces between the two phases. The main innovative aspects and goals of the COMPAGNON project are: • The development of an innovative composite, presenting coupled functions making possible the tuning of the permanent magnet parameters (Mr, Ms, Hc and Ka) by the application of an electric field. These composites will present magnetoelectric coupling coefficients of the order of hundreds of mV.cm-1.Oe-1. • Characterization of the interfaces in the composite by the development of advanced multi-scale techniques: atomic (high resolution TEM, EELS, etc.), nanostructural (FIB-3D) and bulk ones (XPS, PDF, etc.). • Contribute to the understanding of the link between the structure, the composition and the interface within the nanocomposites (nanowires-matrix) and the ME properties evolution. • To shade light either at a fundamental level (nucleation and growth of nanowires and/or core@shell materials, magneto-electric coupling, control of grain size, nature of the interfaces and densification/structuring effect on the composites…) and at the technological one (nanostructuring under magnetic field) in the frame of multifunctional materials. • Provide free rare earths permanent magnets with a magnetic field of the order of 1 T whose magnetic energy could be tuned by an electric field.

The "Plas4chem" project is based on a highly multidisciplinary scientific approach and brings together skills in the fields of microfluidics, plasma processes, chemistry and physics. Our project is based on the development and use of microstructured chemical reactors in order to be able to carry out chemical synthesis reactions without catalyst and without solvent thanks to a precise controlled manipulation of high energy radical species. Microstructured reactors have been attracting interest for several years because of the unprecedented level of control they can bring when conducting chemical reactions and the promise of a rapid scale-up obtained by simple Parallelization. Heat and material transfers as well as mixing processes between reactive fluids are particularly accelerated due to the very small size of the channels. By better controlling the flow and transfer conditions, parasitic side reactions can be suppressed, thus obtaining products with greater selectivity. Thanks to these new type of reactors, it is also possible to explore the potential of alternative sources of activation which have hitherto been difficult to implement in conventional batch reactors. Our major innovation, which was patented in 2015, is based on the association of plasma science, which allows the generation of radical species at pressure and ambient temperature by electron impact, and microfluidics that makes possible the control and transfer of these highly reactive chemical medium with a great precision. The radical species generated by the plasma will be able either to react directly with reactants in the gas phase, the liquid phase serving as both reservoir and extraction phase, or be transferred by diffusion to the liquid phase in order to initiate chemical reactions in the liquid phase. In our project, we propose to explore the reactivity of model molecules (cyclohexane and benzene) when they are brought into contact with plasma discharges generated in gaseous media of variable composition (O2, H2, N2 etc ...pure or mixed with rare gases if needed) in order to control the selectivity of the process towards oxidation, amination, dehydrogenation or carbonylation reactions. This type of reactor thus opens up promising prospects for chemists by simplifying the steps leading to the desired molecules and the development of activation techniques involving the plasmas could make it possible to envisage new, selective and cleaner reaction pathways without using solvent and catalyst.

Dynamic nuclear polarisation (DNP) is a powerful method that enhances NMR sensitivity by transferring the large spin polarisation of electrons to nuclei. But DNP is also limited because it requires cryogenic temperatures and paramagnetic doping that lower resolution and sensitivity. A much better method would thus be direct polarisation of a given material from an external and highly polarisable substrate. Synthetic diamonds containing nitrogen-vacancy centres would be an ideal platform to perform this operation due to the large nuclear polarisations achievable upon laser illumination at room temperature. Such spin polarisations could possibly be transferred from the diamond to another material, thus leading to a disrupting general method for enhancing NMR sensitivity. This proposal aims to overcome this challenge by combining new instrumentation with tailored diamonds to maximise the nuclear spin polarisation and to study the efficiency of its transfer across the diamond interface.