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Author(s):
H. Kuramoto, K. Toi, N. Haraki, K. Sato, J. Xu, A. Ejiri, K. Narihara, T. Seki, S. Ohdachi, K. Adati, R. Akiyama, Y. Hamada, S. Hirokura, K. Kawahata and M. Kojima
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Title:
Study of Toroidal Current Penetration during Current Ramp in JIPP T-IIU with Fast Response Zeeman Polarimeter
Date of publication:
Jan. 1997
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Key words:
Tokamak Plasma, Toroidal Current Penetration, Zeeman Polarimeter, Neoclassical Electrical Conductivity, Tearing Modes
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Abstract:
The toroidal current penetration is studied in current ramp experiments of the JIPP T-IIU tokamak. The poloidal magnetic field profile in the peripheral region of a plasma (0.5 leq rho leq 1.0) has been measured directly with a newly developed fast response Zeeman polarimeter. The experimental results indicate that an obvious skin effect of toroidal current density is clearly observed during both the current ramp-up and ramp-down experiments. The experimentally obtained toroidal current density profiles are well described by the profiles calculated on the assumption of the neoclassical electrical conductivity. Quasi-linear Delta'-analysis of tearing modes for the measured current density profile is consistent with time behaviour of coherent MHD modes such as m=4/n=1 or m=3/n=1 (m: poloidal mode number, n: toroidal mode number) often observed during the current ramp-up phase. The effect of these MHD modes on current penetration during the current ramp-up discharges is studied.
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