Proof-of-principle experiments on the concept of moving-surface plasma-facing components—hydrogen recycling over a titanium-gettered rotating drum

In the magnetic fusion community much attention has recently been directed to particle control in the existing confinement experiments, as it is recognized that the core plasma performance can directly be affected by the edge conditions. However, it is still true that there is no clear strategy to cope with the needs for steady-state reactor operation. That is that, due to the saturation nature, wall conditioning such as boronization is not applicable for fuel and impurity particles control in steady-state devices, requiring a start from enabling concepts development. As a possible solution, the concept of moving-surface plasma-facing components (MS-PFCs) was proposed in our previous work and in the present work proof-of-principle experiments have been conducted. In this concept, the plasma-facing surface is mechanically circulated out-of-pile for regeneration of particle capturing capabilities by coating getter films on it. A prototypical MS-PFC test unit has been constructed for these proof-of-principle experiments, employing a rotating copper drum as the moving surface and titanium as the getter material. It has been indicated that, from Hα light intensity data taken in front of the rotating target, relative to no getter cases, approximately 6% reduced hydrogen recycling has been achieved at steady state. In support of these data, a first-order particle balance model predicts a 7% reduction in hydrogen recycling.