MEASUREMENTS OF CARBON DUST PROPERTY IN EXPERIMENT AND POST-CAMPAIGN SAMPLING ON JT-60U TOKAMAK

Distribution of carbon dust in the plasma discharges was measured, and sublimation of dust was dominant in the scrape-off layer (SQL). Dust collection in the vacuum vessel was performed after the experiment campaign, and the analysis showed that both weight and number of dust were large at the exhaust route of the deuterium gas under the divertor structure. Microscope analysis showed that small dust group (less than 20 mu m) had a statistical population, and that large dusts (larger than 20 mu m) contributed significantly to the total weight. Understanding of the properties of both small and large dusts is important to evaluate surface area for determination of fuel retention.