In order to resolve the power and particle control issue, radiative divertor configurations have recently been applied in several fusion devices and a substantial reduction in the divertor peak heat load has been observed. However, not much has been accomplished in controlling materials impurity generation by the radiative divertor concept. Due to the reduced screening efficiency of radiation-cooled plasmas, material impurities can travel further away from the spot of erosion, increasing the net erosion. Furthermore, radiators such as neon can also contribute to materials erosion. Whereas virtually all existing fusion devices employ low-Z materials such as carbon for plasma-facing components, future reactor studies often choose tungsten for longer lifetime. The hesitation for extensive use of high-Z materials is due to the radiation loss effect, a critical issue that would take decades of worldwide effort to resolve.

Turning to wall conditioning and its effect on plasma confinement, there have been several breakthroughs over the last decade, including helium glow discharge conditioning, boronization and recently lithium conditioning. By nature, however, the wall conditioning effects obtained by these techniques have finite lifetime. The only technique that has demonstrated non-saturable reduced recycling so far is solid target boronization (STB). However, continuous tritium co-deposition with STB would result in a safety issue.

Discussed in this paper is the moving-belt plasma-facing component (MB-PFC) concept to resolve such technical dilemma. This MB-PFC concept allows inline sub-systems not only for continuous getter coating for steady-state impurity control, but also for continuous heat removal and tritium recovery, all that can be located outside the reactor. To minimize complicated MHD effects, semi-metals or semi-conductor materials such as C-C or SiC-SiC composites are proposed for the moving belt. Currently considered for the getter are lithium, beryllium and boron.

From the preliminary analysis, the following features of MB-PFCs have been identified. The surface-averaged belt erosion is independent of belt-speed and it is possible to set the getter coating condition to achieve zero-net erosion. The heat removal can be done either radiatively or by contact with a heat sink, depending on the heat loading condition. Also, the tritium recovery can be as high as 80%. More details of the concept analysis and extrapolation to the reactor condition will be presented at the meeting.