Density Collapse Events Observed in the Large Helical Device
β Scribed by S. Ohdachi; R. Sakamoto; J. Miyazawa; T. Morisaki; S. Masuzaki; H. Yamada; K.Y. Watanabe; V.R. Jacobo; N. Nakajima; F. Watanabe; M. Takeuchi; K. Toi; S. Sakakibara; Y. Suzuki; Y. Narushima; I. Yamada; T. Mianami; K. Narihara; K. Tanaka; T. Tokuzawa; K. Kawahata; LHD Experiment Group
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 999 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0005-8025
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β¦ Synopsis
Abstract
A core density collapse (CDC) phenomenon is a rapid collapse events observed in super dense core (SDC) plasma with internal diffusion barrier (IDB) in the Large Helical Device (LHD). By CDC, the central beta is decreased by up to 50%. The collapse starts from the edge region of the plasma. CDCs appear with plasma parameters where the highβn ballooning modes are unstable at Ο± βΌ 0.8. With less collisional conditions, m = 1 type oscillations are observed with similar beta profile. The origin of the m = 1 oscillations is not clarified (Β© 2010 WILEYβVCH Verlag GmbH & Co. KGaA, Weinheim)
π SIMILAR VOLUMES
The Large Helical Device (LHD) is a heliotron/torsatron-type confinement device (B -4 T, R = 3.9 m) equipped with a helical divertor. In the LHD configuration, the plasma region is shifted inwards approximately a third of the plasma minor radius relative to the center of the two pairing helical coil
We report results of folded waveguide antenna experiments with high power, up to 1 MW, which include the dependence of plasma loading resistance on the plasma density and how much r.f. power can be delivered. We propose its application to the large helical device, which is a heliotron-torsatron devi