Dust in fusion devices—a multi-faceted problem connecting high- and low-temperature plasma physics

TLDR

Dust, ranging from nanometers to tens of micrometers, forms in fusion devices via plasma–surface interactions and, while currently minor, poses future risks due to its radioactivity, chemical reactivity, and ability to travel and charge, potentially disrupting discharges or enabling removal. The paper discusses multi‑faced dust problems by integrating insights from fusion research and low‑temperature dusty plasma studies.

Abstract

Small particles with sizes between a few nanometers and a few 10 µm (dust) are formed in fusion devices by plasma–surface interaction processes. Though it is not a major problem today, dust is considered a problem that could arise in future long pulse fusion devices. This is primarily due to its radioactivity and due to its very high chemical reactivity. Dust formation is particularly pronounced when carbonaceous wall materials are used. Dust particles can be transported in the tokamak over significant distances. Radioactivity leads to electrical charging of dust and to its interaction with plasmas and electric fields. This may cause interference with the discharge but may also result in options for particle removal. This paper discusses some of the multi-faceted problems using information both from fusion research and from low-temperature dusty plasma work.