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Author(s):
K. Ida, Y. Miura, S -I. Itoh, J.V. Hofmann, A. Fukuyama, S. Hidekuma, H. Sanuki, H. Idei, H. Yamada, H. Iguchi, K. Itoh
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Title:
Physical Mechanism Determining the Radial Electric Field and its Radial Structure in a Toroidal Plasma
Date of publication:
Oct. 1994
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Key words:
radial electric field, plasma rotation, charge-exchange spectroscopy, L-mode and H-mode, TTMP damping, bifurcation of radial electric field, radial structure
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Abstract:
Radial structures of plasma rotation and radial electric field are experimentally studied in tokamak, heliotron/torsatron and stellarator devices. The perpendicular and parallel viscosities are measured. The parallel viscosity, which is dominant in determining the toroidal velocity in heliotron/torsatron and stellarator devices, is found to be neoclassical. On the other hand, the perpendicular viscosity, which is dominant in dictating the toroidal rotation in tokamaks, is anomalous. Even without external momentum input, both a plasma rotation and a radial electric field exist in tokamaks and heliotrons/torsatrons. The observed profiles of the radial electric field do not agree with the theoretical prediction based on neoclassical transport. This is mainly due to the existence of anomalous perpendicular viscosity. The shear of the radial electric field improves particle and heat transport both in bulk and edge plasma regimes of tokamaks.
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