Evolution of Radiation Distribution With RMP Assisted Detachment in LHD

The infrared imaging bolometer provides an image of the broadband radiation from a high-temperature plasma. In the Large Helical Device, an operational mode known as detached plasma, which has low plasma flux to the wall and high radiation, is easily achieved and maintained through the external application of a magnetic island to the ergodic edge region. In this paper, we show the evolution of the radiation pattern as the density increases and the plasma detaches and compare it with the corresponding evolution of the synthetic images predicted by the EMC3/EIRENE impurity transport code. The comparison shows good qualitative agreement as the radiation shifts from the helical divertor X-point before detachment to the magnetic island X-point after detachment and then to the magnetic island O-point at higher density.