Author/Authors :
Peterson، نويسنده , , B.J. and Masuzaki، نويسنده , , S. and Sakamoto، نويسنده , , R. and Sato، نويسنده , , K. and Inagaki، نويسنده , , S. and Sagara، نويسنده , , A. and Ohdachi، نويسنده , , S. and Nakamura، نويسنده , , Y. and Noda، نويسنده , , N. and Xu، نويسنده , , Y. and Rice، نويسنده , , J.E. and Ashikawa، نويسنده , , N. and Yamamoto، نويسنده , , S. and Takechi، نويسنده , , M. and Toi، نويسنده , , K. and Morita، نويسنده , , S. and Goto، نويسنده , , M. ، نويسنده ,
Abstract :
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 Raxis=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%.
