Irradiation, characterization, and modelling of new advanced materials for inertial fusion energy

This research was carried out in order to contribute to predict, to understand and to solve some of the bottle necks for fusion to become a reality. The most part of the work was devoted to the development of materials with improved properties to be used for plasma facing application, permeation and corrosion barriers. Focusing on Plasma Facing Materials (PFM) we have modelled the thermomechanical behaviour of the tungsten First Wall (FW) in the three foreseen HiPER laser fusion scenarios (Experimental, Prototype and Demo). We have identified that the lifetime of the FW is limited by fatigue loading and we have estimated it for the different scenarios. Moreover, we have calculated the minimum thickness of a W FW to fulfil its protection task. We have also studied the role of grain boundaries on the radiation-induced damage and on the light species in W. We have studied the thermal stability of nanostructured W by carrying out isothermal annealing and by subjecting the samples to large thermal loads in a plasma focus facility. Finally, we have analysed the capabilities of the ESS-Bilbao (Spanish ion/neutron source inside the frame of the European Spallation Source system in Lund) facility to study the materials behavior under thermal loads in the presence of ions simultaneously. We conclude that this facility is suitable to test PFM under inertial fusion conditions. Concerning the development of permeation barriers, we have studied the influence of the sputtering parameters and of the surface finishing of the substrate on the adhesion of SiC coatings to Ni substrates. We have performed permeation experiments on homogeneous and SiC coatings well adhered to the substrates, finding out a PRF value lower than that previously reported for coatings deposited on steel. Regarding the development of corrosion protection coatings, we have studied two different materials: SiC and nanostructured W. For this purpose, coatings were deposited on EUROFER substrate. We have optimized the adhesion of the coatings to the substrate. So far, accelerated corrosion tests indicate that nanostructured W coating may work as a suitable corrosion protection layer at temperatures in the range 350–550°C. We have also worked on rector technology. In this subject we have developed a conceptual design of HiPER final lenses and of a ceramic breeding blanket with tritium breeding ratio tuning capabilities. By combining experiments and computer simulations, we have studied the different processes involved in the permanent modification of silica formed by ion-induced high electronic excitation. Results allows us defining the threshold energy density for track formation and describe the different processes which leads to permanent modification. The proposed model can be used to described ion-induced modifications in different materials. We have studied the capabilities of the ESSBilbao to study of materials neutron irradiation under nuclear fusion conditions, focusing on structural, silica-based optical and ceramics materials as well as, on electronic components. We have also analysed the use of lasers for neutron production. (author)