In the Large Helical Device （LHD）, two different divertor configurations, i.e. helical divertor （HD） and local island divertor （LID）, are utilized to control the edge plasma. The HD with two X-points is an intri...In the Large Helical Device （LHD）, two different divertor configurations, i.e. helical divertor （HD） and local island divertor （LID）, are utilized to control the edge plasma. The HD with two X-points is an intrinsic divertor for heliotron devices, accompanied with a relatively thick ergodic layer outside the confinement region. Edge and divertor plasma behavior from low density to high density regimes is presented, referring to the divertor detachment. The effect of the ergodic layer on the edge transport is also discussed. On the other hand, the LID is an advanced divertor concept which realizes a high pumping efficiency by the combination of an externally induced magnetic island and a closed pumping system. Experimental results to confirm the fundamental divertor performance of the LID are presented.展开更多
A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device （LHD）. A plasma of ne = 0.8 × 10^19 m^-3 and T10 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and avera...A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device （LHD）. A plasma of ne = 0.8 × 10^19 m^-3 and T10 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. Total injected heating energy was 1.3 G J, which was a quarter of the prepared RF heating energy. One of the keys to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by shifting the magnetic axis inward and outward.展开更多
Results of the two-dimensionally reconstructed distribution of soft X-ray emission in HL-2A and electromagnetic radiation in large helical device （LHD） are presented. Hardware improvements of in-vessel soft X-ray ca...Results of the two-dimensionally reconstructed distribution of soft X-ray emission in HL-2A and electromagnetic radiation in large helical device （LHD） are presented. Hardware improvements of in-vessel soft X-ray cameras and the development of tomographic software have made detailed and visual studies of soft X-ray emission possible in HL-2A. Several algorithms are employed in order to get as detail as possible in the images while keeping the guiding assumptions to a minimum. Recently success has been achieved in applying a 2D peeling away algorithm for tomographic reconstruction of LHD bolometric data jointly under the China-Japan collaboration. The data analysed so far have been used to study magnetohydrodynamic （MHD） instabilities on HL-2A tokamak and radiation losses on LHD.展开更多
基金supported by NIFS under Grant(No.NIFS05ULPP506)in part by the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusion
文摘In the Large Helical Device （LHD）, two different divertor configurations, i.e. helical divertor （HD） and local island divertor （LID）, are utilized to control the edge plasma. The HD with two X-points is an intrinsic divertor for heliotron devices, accompanied with a relatively thick ergodic layer outside the confinement region. Edge and divertor plasma behavior from low density to high density regimes is presented, referring to the divertor detachment. The effect of the ergodic layer on the edge transport is also discussed. On the other hand, the LID is an advanced divertor concept which realizes a high pumping efficiency by the combination of an externally induced magnetic island and a closed pumping system. Experimental results to confirm the fundamental divertor performance of the LID are presented.
基金supported in part by the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusion
文摘A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device （LHD）. A plasma of ne = 0.8 × 10^19 m^-3 and T10 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. Total injected heating energy was 1.3 G J, which was a quarter of the prepared RF heating energy. One of the keys to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by shifting the magnetic axis inward and outward.
基金supported by the JSPS-CAS Core University Program in the field of Plasma and Nuclear Fusion
文摘Results of the two-dimensionally reconstructed distribution of soft X-ray emission in HL-2A and electromagnetic radiation in large helical device （LHD） are presented. Hardware improvements of in-vessel soft X-ray cameras and the development of tomographic software have made detailed and visual studies of soft X-ray emission possible in HL-2A. Several algorithms are employed in order to get as detail as possible in the images while keeping the guiding assumptions to a minimum. Recently success has been achieved in applying a 2D peeling away algorithm for tomographic reconstruction of LHD bolometric data jointly under the China-Japan collaboration. The data analysed so far have been used to study magnetohydrodynamic （MHD） instabilities on HL-2A tokamak and radiation losses on LHD.
