Non-ambipolar Transport by Trapped Particles in Tokamaks
Authors: J.K. Park, A.H. Boozer, and J.E. Menard
Abstract:
Small non-axisymmetric perturbations of the magnetic field can greatly change the performance of tokamaks through non-ambipolar transport. A number of theories have been developed, but the predictions were not consistent with experimental observations in tokamaks. This Letter provides a resolution, with a generalized analytic treatment of the non-ambipolar transport. It is shown that the discrepancy between theory and experiment can be greatly reduced by two effects: (1) The small fraction of trapped particles for which the bounce and precession rates resonate. (2) The non- axisymmetric variation in the field strength along the perturbed magnetic field lines rather than along the unperturbed magnetic field lines. The expected sensitivity of ITER to non-axisymmetries is also discussed.
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Accepted to: Physical Review Letters MS#LW11502
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Download PPPL-4375 (pdf 587KB 10pp)
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