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Author(s):
N. Nakajima and M. Okamoto
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Title:
Rotations of Bulk Ions and Impurities in Non-Axisymmetric Toroidal Systems
Date of publication:
July 1991
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Key words:
neoclassical theory, non-axisymmetric system, geometric factor, rotation, viscosity, impurity, 1/nu regime, plateau regime, Pfirsch-Schluter regime
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Abstract:
Neoclassical rotations are investigated theoretically for a plasma consisting of electrons, bulk ions, and impurities in non-axisymmetric toroidal systems. Impurity ions are assumed to lie in the Pfirsch-Schluter collisionality regime. The results include the case of tokamaks. It is found that the rotations of impurities are generally different from those of bulk ions. The difference comes from mainly the different diamagnetic flows between bulk ions and impurities. In the 1/nu regime or banana regime the gradient of bulk ion temperature may be another cause for the different rotations between the two species. However, in the region where the configuration is far from the axisymmetry the cause of different rotations is just the different diamagnetic flows. As the poloidal rotations depend on the radial electric field contrary to the axisymmetric system, a relationship, which does not include the radial electric field, can be derived between poloidal and toroidal rotations. By estimating this relationship based on the measured rotations the present neoclassical theory can be validated without knowledge of radial electric field.
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