Imaging Bolometers for Visualization of Plasma Radiation and Cross-Validation of Three Dimensional Impurity Transport Models for the Large Helical Device

Abstract

The InfraRed imaging Video Bolometer (IRVB) measures the radiation from the plasma in two dimensions, giving an image of the plasma radiation power loss. Using a geometry matrix calculated from a model of the LHD first wall, the IRVB sightline geometry and a three dimensional (3D) plasma grid, a synthetic instrument is developed using the 3D carbon impurity radiation results of the EMC3-EIRENE edge impurity transport code as an input. The output of the synthetic instrument are images of the plasma radiation at the IRVB foil due to the EMC3-EIRENE code, which are qualitatively compared with preliminary experimental images from the IRVB. Such a comparison for detached discharges in LHD in which an externally induced m/n = 1/1 magnetic island is applied shows that when the magnetic island is moved 36 degrees toroidally the enhanced radiation in the x-points of the magnetic island also moves as predicted by the EMC3-EIRENE code.

3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

“…In the figure, one clearly sees the change of radiation pattern from the peaked inboard side radiation without MP (Fig.13 (b)) to the X-point radiation with MP application (Fig.13 (a)). As shown in Fig.13, the radiation distribution measurements with both AXUVD as well as imaging bolometer show the signature of the intense X-point radiation, confirming, at least qualitatively, agreement with the code prediction for the modification of the 3D radiation structure [160,161,162]. The operation domain for the stable detachment with an MP is found to be characterized by the distance between the island X-point and the LCFS,…”

Impact of 3D magnetic field structure on boundary and divertor plasmas in stellarator/heliotron devices

“…The 3D numerical simulation with EMC3-EIRENE shows that with RMP application intense radiation is formed along the trajectory of the X-point of the m/n=1/1 island, while without the RMP the radiation is localized at the inboard side throughout the torus [95]. The radiation distribution measurements with both AXUVD as well as imaging bolometer show the signature of the intense X-point radiation, confirming, at least qualitatively, agreement with the code prediction for the modification of the 3D radiation structure [96,97,98]. The operation domain for the stable detachment with an RMP is shown in Fig.8 in terms of the distance between the island X-point and the LCFS, as that in…”

Overview of transport and MHD stability study: focusing on the impact of magnetic field topology in the Large Helical Device

“…The radiation distribution measurements, with both the AXUVD and the imaging bolometer, show the signature of the intense X-point radiation, confirming, at least qualitatively, agreement with the code prediction for the modification of the 3D radiation structure [59][60][61], as shown in figure 9. In the detached plasma, a broadening of the divertor flux and positive spikes of ion saturation currents, as well as the reduction of the divertor flux at the strike point, were clearly confirmed on the divertor plate [62].…”

“…The radiation distribution measurements with both AXUVD as well as imaging bolometer show the signature of the intense X-point radiation, confirming, at least qualitatively, agreement with the code prediction for modification of 3D radiation structure [59][60][61], as shown in Fig. 9.…”