Introduction: Plasma-wall interaction in fusion devices encompasses a wide variety of processes. On a short timescale these include deposition of energetic plasma particles (primarily hydrogen and helium) into the surface, physical and chemical sputtering of surface material into the plasma, and reflection and desorption of particles from the surface. On a longer timescale the processes include diffusion of hydrogen and helium in the wall and changes in surface composition, morphology and material microstructure due to plasma bombardment and (in a reactor) neutron irradiation. Together these processes are extremely important in determining the plasma performance, the lifetime of plasma-facing components, trapping and retention of the tritium fusion fuel in the wall, and ultimately the feasibility of fusion power production. The gap between what is known about plasma-material interaction and what is needed to design a fusion reactor is most severe for the effects of radiation damage on hydrogen retention properties of plasma-facing materials. Computations are particularly important for this problem, because experiments cannot fully simulate the radiation conditions in a fusion device. Appropriate computational materials tools range from statistical or otherwise averaged (binary collision approximation, kinetic Monte Carlo) and mechanical (molecular dynamics) models to semiempirical (tight binding) density functional theory codes and first principles quantum mechanical codes for inhomogeneous materials. Any of these codes has its own needs for fundamental data, which are in many cases obtained by parameterization of results of other calculations.

Purpose: The conference is intended to bring together researchers from the areas of fusion energy science and materials science in order to review advances in computational studies of plasma-material interaction processes and the evolution of material microstructure in fusion devices. Within this area the programme will emphasize work that is relevant to hydrogen (tritium) trapping and transport in candidate fusion reactor wall materials. This includes modelling of the effects of irradiation upon material microstructure and modelling to understand the influence of microstructure on hydrogen trapping and transport. Participants with a background in plasma-wall interaction in fusion experiments should return from the conference with a richer understanding of the wide range of computational methods that are used for development of plasma-material interaction data and material properties data for fusion plasma and fusion materials modelling. Participants from the area of materials science should obtain guidance about new work that is most needed to improve understanding of plasma-material interaction processes and material damage processes that are relevant for fusion energy development. The conference format is meant to encourage new collaborations on computational studies of plasma-material interaction in fusion devices.

Topics: The conference programme will emphasize uses of the more fundamental computational tools (based on quantum mechanics) and parameterization of results from such tools in the form of interaction potentials and transition rates for applied studies. Specific topics include the following.

* Direct uses of ab initio and semi-empirical quantum mechanical codes for study of materials microstructure, trapping and transport of hydrogen and helium in fusion wall materials.
* Optimization of parameters in semi-empirical codes and parameterization of results of quantum mechanical calculations in the form of interaction potentials and transition rates for classical models.
* Molecular Dynamics, Binary Collision Approximation and Kinetic Monte Carlo studies of plasma-material interaction, radiation damage processes and material and surface evolution.
* Multi-method and multi-scale simulations; acceleration approaches.
* Uncertainty estimation and uncertainty propagation from quantum mechanical calculations through interaction potentials to outputs of longer time-scale calculations.
* Parameterization of material microstructure and its effect on mobility and trapping of hydrogen and helium in fusion wall materials.
* Simulation and interpretation of diagnostics of material microstructure, radiation damage, hydrogen and helium in fusion materials and plasma-material interaction Participants will be active researchers in the subject area of the conference and we expect a scientific contribution (talk or poster) from each participant.