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Fusion Science and Technology
Latest News
Vogtle-3 shuts down for valve issue
One of the new Vogtle units in Georgia was shut down unexpectedly on Monday last week for a valve issue that has been investigated and repaired. According to multiple local news outlets, Georgia Power reported on July 17 that unit 3 was back in service.
Southern Company spokesperson Jacob Hawkins confirmed that Vogtle-3 went off line at 9:25 p.m. on July 8 “due to lowering water levels in the steam generators caused by a valve issue on one of the three main feedwater pumps.”
Kenji Tanaka, Clive Michael, Masayuki Yokoyama, Osamu Yamagishi, Kazuo Kawahata, Tokihiko Tokuzawa, Mamoru Shohji, Hiroshi Yamada, Jyunichi Miyazawa, Shigeru Morita, Katsumi Ida, Mikiro Yoshinuma, Kazumichi Narihara, Ichihiro Yamada, Shigeru Inagaki, LHD Experimental Group, Leonid Vyacheslavov, Andrei Sanin, Sadayoshi Murakami, Arimitsu Wakasa
Fusion Science and Technology | Volume 51 | Number 1 | January 2007 | Pages 97-111
Technical Paper | Stellarators | doi.org/10.13182/FST07-A1291
Articles are hosted by Taylor and Francis Online.
The characteristics of particle transport in three different magnetic configurations are studied from density modulation experiments in the Large Helical Device (LHD). These three configurations are represented as different magnetic axis positions (Rax) of the vacuum field. Experiments were carried out in a range of different heating powers for each configuration with almost constant density. The experimental values of particle diffusion coefficients (D) and particle convection velocities (V) are compared with neoclassical estimates. The value of D is found to be anomalously large compared to neoclassical values in both the core and edge in all configurations. At low collisionality, this anomaly tends downward. The core convection velocities are comparable with neoclassical estimates. In more-outward-shifted configurations, particle transport is enhanced. The electron temperature and electron temperature gradient are the determinate parameters for D and V, respectively, in each configuration. The effective helical ripple is one of the important parameters for particle transport in the LHD; however, other hidden parameters exist. The role of fluctuations in particle transport is investigated from turbulence measurements using a two-dimensional phase contrast interferometer. Three kinds of fluctuation having different locations, propagation direction, and peak wave number are observed. One of these, which exists in the outermost edge region and propagates in the ion diamagnetic direction in the laboratory frame, plays a possible role in edge anomalous diffusion. The amplitudes of ion diamagnetic fluctuation components are compared with the linear growth rate of the ion temperature gradient mode.