Atomistic Simulations of the Fusion-Plasma Material Interface

A key issue for the successful performance of current and future fusion reactors is understanding chemical and physical processes at the Plasma Material Interface (PMI). The material surfaces may be bombarded by plasma particles in a range of impact energies (1 eV - a few keV) and kept at a range of temperatures (300 - 1000 K). The dominant processes at the PMI are reflection and retention of impacting particles and sputtering (chemical and physical). Sputtering leads to surface erosion and pollution of the plasma, both of which degrade reactor performance. Retention influences the recycling of the plasma, and in the case of tritium, raises the question of radioactive waste. PMI is a multi-scale problem, ranging from timescales of femtoseconds to years and spatial scales between Angstroms to meters. The main goal of this dissertation is to model PMI processes at the nanometer/nanosecond scale using atomistic Molecular Dynamic (MD) approaches. In particular, simulations have been done on mixed amorphous materials: hydrogenated, lithiated, and oxygenated carbon; bombarded by H isotopes using Classical Molecular Dynamics (CMD) and a Quantum-Classical Molecular Dynamics (QCMD) approach.