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  • KUMAZAWA Ryuhei, M. Takashi, +78 authors FUJIWARA Masami
An Ion Cyclotron Range of Frequency (ICRF) heating experiment on the Large Helical Device has opened up a new field for nuclear fusion research. The plasma was sustained for more than I minute by the injected ICRF power only. The injected RF power was 0.8 MW. The plasma stored energy, the line average electron density, the central electron temperature and(More)
  • NISHIMURA Kiyohiko, KAWAHATA Kazuo, +48 authors YOKOYAMA Masayuki
Transition from the ion root to the electron root in neutral beam heated plasmas was observed in the Large Helical Device for the first time. The measured values of the radial electric field were found to agree well with those estimated by neoclassical theory. The pedestal configuration, which is characterized by a high edge temperature gradient, was(More)
  • M Osamu, OHYABU Nobuyoshi, +91 authors FUJIWARA Masami
  • 2000
In the third campaign MW) were used to heat the plasma in LHD. The carbon tiles were installed as divertor plates, resulting in significant reduction in metal impurity concentration (Fe). The maximum field used in the experiment is 2.gT.IJpgrading of the key hardware systems led to (i) higher T" [T,(0) = 4.4keY atn"= J.J x 1018m-3 and Po6, = 1.8 Mwl, (ii)(More)
  • IGUCHI Harukazu, FUJISAWA Akihide, +9 authors TAKAHASHI Chihiro
Static and dynamic behaviors of core plasma potentials in toroidal helical plasmas have been studied by the use of a 200 keV heavy ion beam probe (HIBP) in the Compact Helical System (CHS). Fast time response and local measurements of this diagnostic method have brought about various new insights both on transport and MHD phenomena in toroidal helical(More)
In the local Electron Cyclotron Heating (ECH) experiments, high electron temperature plasmas have been olrtained in Compact Helical System (CHS), and recently in the Large Helical Device (LHD). The internal transport barrier (ITB) with strong positive radial electric field has been experimentally observed in CHS, which reduces neo-classical ripple transport(More)
  • SHIMOZUMA Takashi, S Motoyasu, +6 authors MORIMOTO Shigeyukit
Development of a vacuum barrier window for high power millimeter waves is one of the key technical issues to realize CW (Continuous Waves) ECH system. For this purpose, we have been developing a forced gas-cooled Brewster window with low loss silicon nitride composite (SN-287 Kyocera) for megawatt and CW power transmission. The thermal analysis of the(More)
The confinement property of neutral beam (NB)-injected fast ions has been investigated by means of neutron diagrostics and neutral particle analyzer in Compact Helical System (CHS). In a series of this experiments, an 17o deuterium-doped short pulse NBs with the duration of 6 ms was tangentially injected into target deuterium plasmas. After beam turn-off,(More)
  • OZAKI Tetsuo, KADO Shinichiro, +21 authors TILIA Benedettoa
The development of high energy neutral particle measurement system for ion temperature measurements and high energy particle confinement analysis during neutral beam injection and ion cyclotron resonance frequency heating experiments in the Large Helical Device (LHD) is described. The control, data acquisition systems and the horizontal movable stage are(More)
  • YOKOYAMA Masayuki, WAKASA Arimitsu, K Shin
  • 2005
Transition property of the radial electric field (Er) in LHD have been theoretically investigated and also applied to explain experimental results. Especially, effects of the helicity of the magnetic configuration on the condition to realize the electron root are examined. Larger helicity makes the threshold collisionality higher. This is attributed to the(More)
Net toroidal currents of up to 60 kA have been observed in NBI plasmas of LHD. Time development of toroidal currents observed in balanced NBI plasmas have been analyzed for the identification from a viewpoint of bootstrap current. The results suggest that observed currents are quantitatively consistent with the theoretical model. The active control of the(More)