MHD stability of the Large Helical Device (LHD) plasmas produced with intenseneutral beam injection is experimentally studied. When the steep pressure gradient near the edge isproduced through L-H transition or linear...MHD stability of the Large Helical Device (LHD) plasmas produced with intenseneutral beam injection is experimentally studied. When the steep pressure gradient near the edge isproduced through L-H transition or linear density ramp experiment, interchange-like MHD modes whoserational surface is located very close to the last closed flux surface are strongly excited in acertain discharge condition and affect the plasma transport appreciably. In NBI-heated plasmasproduced at low toroidal field, various Alfven eigenmodes are often excited. Bursting toroidalAlfven egenmodes excited by the presence of energetic ions induce appreciable amount of energeticion loss, but also trigger the formation of internal and edge transport barriers.展开更多
A broadband frequency tunable microwave reflectometer system, which has the abil- ity of fast and stable frequency sweeping operation, is applied in the large helical device （LHD） to measure the boundary of the high...A broadband frequency tunable microwave reflectometer system, which has the abil- ity of fast and stable frequency sweeping operation, is applied in the large helical device （LHD） to measure the boundary of the high-temperature plasma. When the microwave is launched, with extraordinary polarization, from the low field side of the magnetic field with its frequency swept from low to high, the microwave of minimum right-hand cut-off frequency is reflected most out- side. We can then estimate the plasma boundary position by measuring the change of the reflected power from the cut-off layer.展开更多
基金The project supported by the Core-University Program between Japan and China on Plasmas and Nuclear Fusion, and a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science
文摘MHD stability of the Large Helical Device (LHD) plasmas produced with intenseneutral beam injection is experimentally studied. When the steep pressure gradient near the edge isproduced through L-H transition or linear density ramp experiment, interchange-like MHD modes whoserational surface is located very close to the last closed flux surface are strongly excited in acertain discharge condition and affect the plasma transport appreciably. In NBI-heated plasmasproduced at low toroidal field, various Alfven eigenmodes are often excited. Bursting toroidalAlfven egenmodes excited by the presence of energetic ions induce appreciable amount of energeticion loss, but also trigger the formation of internal and edge transport barriers.
基金a Grant-in-Aid for Scientific Research on Priority Areas (Nos.18035015,20026010)a Grant-in-Aid for Young Scientists (A)(No.18686075)the Ministry of Education,Culture,Sports,Science and Technology Japan and also a budgetary Grant-in-Aid (No.NIFS08ULHH508)of National Institute for Fusion Science and the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusion
文摘A broadband frequency tunable microwave reflectometer system, which has the abil- ity of fast and stable frequency sweeping operation, is applied in the large helical device （LHD） to measure the boundary of the high-temperature plasma. When the microwave is launched, with extraordinary polarization, from the low field side of the magnetic field with its frequency swept from low to high, the microwave of minimum right-hand cut-off frequency is reflected most out- side. We can then estimate the plasma boundary position by measuring the change of the reflected power from the cut-off layer.
