Plasma-wall interactions in tokamaks, a scope between physics and chemistry

Plasma-wall interactions in tokamaks, a scope between physics and chemistry. Remarkable results have been obtained in thermonuclear fusion researches since the first experiments performed in tokamaks, about 40 years ago. The next step is now to succeed in controlling deuterium-tritium long discharges in order to demonstrate the feasibility of fusion energy for peaceful purposes. This is the aim of ITER (International Thermonuclear Experimental Reactor), the next magnetic fusion device. While great progresses have been made, new questions emerged and the plasma-wall interactions are one of them. In this paper, we show that this domain is interdisciplinary, particularly because of the presence of carbon and hydrogen. Indeed, we highlight the fundamental role played by chemical processes in the interactions between hydrogen and carbon-based materials and the beneficial contribution of quantum-modelling works in the understanding of them. Ab initio calculations, using the density functional theory, allow studying chemical reactivity of the concerned species. Elementary processes and associated energies can be investigated without any empirical assumptions. The understanding of the elementary reactions, the calculation of the energy transfer and barriers of reaction, together with the modelling of reactions through quantum molecular dynamics provide helpful and more realistic input data to plasma-wall interaction simulation codes.