Characterization of dust collected from ASDEX-Upgrade and LHD

Dust has been collected and analyzed from Axial Symmetric Divertor Experiment-Upgrade (ASDEX-Upgrade) and the Large Helical Device (LHD). A total quantity of 984.4 mg of dust was collected from ASDEX-Upgrade, whereas only 17.6 mg was obtained from roughly equal sampling areas in LHD. Particle sizes determined by count-based measurements from all locations in ASDEX-Upgrade averaged 3.33 μm, and LHD dust had an average size of 9.64 μm. Dust from both devices was composed mainly of carbon and constituents of stainless steel, the materials used for most plasma-facing surfaces and the vacuum vessels. Specific surface area (SSA) of the dust from ASDEX-Upgrade ranged between 0.70 and 3.70 m2/g. LHD samples contained insufficient mass for measuring SSA. Details from the analysis of each dust collection activity in ASDEX-Upgrade and LHD are described in this paper.