In the large helical device (LHD) radiation profiles measured using arrays of resistive metal, foil bolometers are used to investigate the change in radiation resulting from a replacement of stainless steel divertor plates with graphite tiles between the second and third experimental campaigns. In particular, for the magnetic configuration of Aaxis -3.6 m and at line averaged densities below 3 × 1019 m-3, a reduction of the radiated power fraction from 35% in the second campaign to down to 12% in third campaign was observed. Comparing similar shots (in terms of discharge parameters) from the second and third cycles the core (0 < r/a. < 0.79) radiation fraction was reduced from 44% to 30% of the total radiation. Spectroscopic measurements show a corresponding decrease in radiation from iron. Comparing long pulse discharges the radiated power fraction reduced from greater than 67% during the density limiting oscillation observed in the second campaign to 20% during the third campaign with a reduction in the respective core radiation fractions from 63% to 37%.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Materials Science(all)
- Nuclear Energy and Engineering