Asymmetric divertor plasma distribution observed in Heliotron J ECH discharges

Edge fluctuation studies in Heliotron J

“…To study low frequency (1-200 kHz) and small-scale (k ? $ 1-2 cm À1 ) fluctuations of density (ion saturation current, I s ) and potential (floating potential, V f ) near the last closed flux surface (LCFS), we used three Langmuir probes, which were a part of a poloidal probe array with 17 pins (#9-#11 probes of the array) [9]. The probe pins were aligned nearly parallel to the shape of the calculated LCFS in one poloidal crosssection of the torus.…”

High-speed 2-D image measurement for plasma-wall interaction studies

“…Heliotron J is a medium sized heliotron device with an L = 1/M = 4 helical axis which can form various magnetic configurations [5][6][7]. The schematic of the experimental setup is shown in Fig.…”

High-speed 2D measurement of edge turbulence phenomena with a fast camera in Heliotron J

“…In these figures, the filamentary structure moved downward. The radial electric field E r of the peripheral region in STD Heliotron J plasma measured by Langmuir probe was negative [9] and the E r · B direction is downward in the image. Therefore, it is expected that the motion of the filamentary structure is affected by the E r · B drift in edge plasma [10].…”