A Comparison of Dust Particles Produced due to Interaction between Graphite and Plasmas: LHD vs Helicon Discharges
نویسندگان
چکیده
To obtain information on formation mechanisms of dust particles of nm in size in fusion devices, in-situ collection of dust particles produced due to interaction between graphite target as plasma facing materials and the plasmas was carried out in a helicon discharge chamber and in Large Helical Device (LHD). Dust particles produced in the helicon discharges are made of carbon and can be classified into three kinds: small spherical dust particles below 1 �m in size, large flakes above 1 �m in size, and agglomerates which consist of primary particles of 10 nm. These features are quite close to those of dust particles collected in LHD, suggesting that the helicon plasma can simulate dust formation processes in divertor region in LHD. Three kinds of dust particles suggest three formation mechanisms: CVD growth of carbon radicals, carbon films peeled from walls, and agglomeration.
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