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Author(s):
M.Yokoyama, K.Itoh, S.Okamura, K.Matsuoka, N. Nakajima, S.-I.Itoh, G. H. Neilson, M. C. Zarnstorff and G.Rewoldt
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Title:
Drift Reversal Capability in Helical Systems
Date of publication:
Oct. 2002
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Key words:
IAEA, fusion energy conference, Lyon
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Abstract:
The maximum-J (J is the second adiabatic invariant) capability, i.e., the drift reversal capability, is examined in quasi-axisymmetric (QAS) stellarators and quasi-poloidally symmetric (QPS) stellarators as a possible mechanism for turbulent transport suppression. Due to the existence of non-axisymmetry of the magnetic field strength in QAS configurations, a local maximum of J is created to cause the drift reversal. The increase of magnetic shear in finite beta ezuilibria also has favorable effect in realizing the drift reversal. The radial variation of the uniform magnetic field component plays a crucial role for the drift reversal in a QPS configuration. Thus, the drift reversal capability and its external controllability are demonstrated for QAS and QPS stellarators, by which the impact of magnetic configuration on turbulent transport can be studied in experiments.
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