On First Wall and Dust Issues in Fusion Devices

Full text: The first wall plays crucial role in the design of any fusion reactor. However, the physics of plasma-wall interactions in fusion devices resulting in the modification of surface morphology and wall material properties, formation of co-deposited layers, bubbles, 'fuzz', dust, etc. is still poorly understood and in many cases there are no even rudimentary models explaining already observed phenomena. Here we address some issues related to the physics of the first wall and dust in fusion devices: The formation of 'hot spots' related to thermal bifurcation caused by the synergy of wall evaporation and plasma transport; We present newly developed model of 'fuzz' growth, which explains all major experimental observations; We report on recent progress in the modeling of hydrogen retention in first wall material with WALLPSI code, and the impact plasma recycling, which can be altered of hydrogen adsorption by Li wall, on edge plasma performance. We also consider the physics of dust-grain interactions for both non-spherical and large grains and discuss the synergetic effects of dust impact on edge plasma parameters and dust dynamics found with self-consistent dust and edge plasma modeling performed with coupled dust (DUSTT) and edge plasma (UEDGE) transport codes. This work was supported by the US DoE under the Grants DEFG02-04ER54852 and DE-FG02-04ER54739 at UCSD. (author)