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M. Sakamoto, S. Itoh, K. Sato, K. Nakamura,
H. Zushi, K. Hanada, E. Jotaki,
K. Makino, S. Kawasaki, H. Nakashima
Advanced Fusion Research Center, Research Institute for Applied Mechanics, Kyushu University 87, Kasuga 816-8580, Japan
Abstract. Current profile control experiments have been carried out in
TRIAM-1M by the combination of two lower hybrid waves (LHW's: 8.2 GHz and
2.45 GHz) with different spectra of parallel refractive index. In this case
the current drive efficiency is improved by > 50% than those of 8.2GHz
LHCD
only and 2.45GHz LHCD only. This is attributed to the synergetic effect of
the combination of the two LHW s. The internal inductance is reduced
depending on the power of the 2.45GHz LHW. This means that the current
profile changes from a peaked profile to a broad one, which is also
supported by hard X-ray measurements. Moreover, the controlled current
profile can be successfully sustained for about 2 orders in magnitude longer
than the current diffusion time. The compatibility of the current profile
control and the improved current drive efficiency is required for future
fusion plasma. It is achieved by the combined LHCD in TRIAM-1M.
IAEA 2001
