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Author(s):
Y. Hamada, A. Nishizawa, Y. Kawasumi, A. Fujisawa, K. Narihara, K. Ida, A. Ejiri, S. Ohdachi, K. Kawahata, K. Toi, K. Sato, T. Seki, H. Iguchi, K. Adachi, S. Hidekuma, S.Hirokura, K. Iwasaki, T. Ido, M. Kojima, J. Koong, R. Kumazawa, H. Kuramoto, T. Minami, I. Nomura, H. Sakakita, M. Sasao, K.N. Sato, T. Tsuzuki, J. Xu, I. Yamada and T. Watari
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Title:
Density Fluctuation in JIPP T-IIU Tokamak Plasmas Measured by a Heavy Ion Beam Probe
Date of publication:
Nov. 1996
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Key words:
tokamak, turbulence, HIBP, NBI
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Abstract:
Multiple and small sample-volume measurements of the density turbulence and potential profile measurement in tokamak plasmas were conducted by a heavy ion beam probe. The obtained wavenumber/frequency spectrum S(k,omega) shows that the cross-section of NBI heated plasmas is divided into three regions of different turbulence characteristics. Outside the reversal layer of poloidal propagation direction of density turbulence, a low-frequency and low-wavenumber mode with ion diamagnetic drift direction dominates. The region encircled by the reversal layer is divided into two parts at nearly perpendicular NBI heating, the region where the propagation velocity is near the E_r/B_t poloidal rotation velocity and the bad-curvature region of very small wavenumber and high propagation velocity. The region of high propagation velocity, found in NBI plasmas, disappears in ohmic plasmas. In addition, a small component which propagates in the ion diamagnetic drift direction is observed in NBI plasmas.
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