Control of Asymmetric Magnetic Perturbations in Tokamaks
Authors: Jong-kyu Park, Michael J. Schaffer, Jonathan E. Menard, and Allen H. Boozer
Abstract:
The sensitivity of tokamak plasmas to very small deviations from the axisymmetry of the magnetic field |δ→(over)Β/→(over)Β|≈ 10–4 is well known. What was not understood until very recently is the importance of the perturbation to the plasma equilibrium in assessing the effects of externally produced asymmetries in the magnetic field, even far from a stability limit. DIII-D and NSTX experiments find that when the deleterious effects of asymmetries are mitigated, the external asymmetric field was often made stronger and with an increased interaction with the magnetic field of the unperturbed equilibrium fields. This paper explains these counter intuitive results. The explanation using ideal perturbed equilibria has important implications for the control of field errors in all toroidal plasmas.
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Published in: Phys. Rev. Lett. 99, 195003 (2007)
doi: 10.1103/PhysRevLett.99.195003
© 2007 The American Physical Society
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PPPL-4262 —Preprint, August 2007; pdf 596 kB