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(TH/6-2) Constructing Integrable Full-Pressure Full-Current Free-Boundary Stellarator Magnetohydrodynamic Equilibrium Solutions.

S. R. Hudson1), D.A. Monticello1), A.H. Reiman1), D.J. Strickler2), S.P. Hirshman2), L-P. Ku1), E. Lazarus2), A. Brooks1), M.C. Zarnstorff1), A.H. Boozer3), G-Y. Fu1), G.H. Neilson1)
1) Princeton Plasma Physics Laboratory, Princeton, USA
2) Oak Ridge National Laboratory, Oak Ridge, TN, USA
3) Columbia University, New York, USA

Abstract.  For stellarators to be feasible candidates for fusion power stations it is essential that the magnetic field lines lie on nested flux surfaces; however, the lack of a continuous symmetry implies that magnetic islands, caused by Pfirsch-Schlüter currents, diamagnetic currents and resonant coil fields, are guaranteed to exist. The challenge is to design the plasma and coils such that these effects cancel. Magnetic islands in free-boundary full-pressure full-current stellarator magnetohydrodynamic equilibria are suppressed using a procedure based on the PIES code [Comp. Phys. Comm., 43:157, 1986] which iterates the equilibrium equations to obtain the plasma equilibrium. At each iteration, changes to a Fourier representation of the coil geometry are made to cancel resonant fields produced by the plasma. The changes are constrained to lie in the nullspace of certain measures of engineering acceptability and kink stability. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible. The method is applied to a candidate plasma and coil design for NCSX [Phys. Plas., 7:1911, 2000].

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IAEA 2003