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Abstract

Recent Tokamak beta optimization studies have indicated the existence of a beta limit proportional to the plasma current (the Troyon limit). A new two step beta optimization procedure is described that attempts to decouple kink and ballooning stability so that the two can be optimized independently. Results for the zero beta case are given as a basis for clarifying the results of the optimization. Stability in a circular cross-section Tokamak at zero beta requires q-axis > 1, q-surface > 2 and zero current density gradient at the surface. If q-axis > 1, modes appear that are higher order in aspect ratio than the kink ordering. These have the form of internal modes inside q = 1, but are stabilized by a conducting shell. For one value of the plasma current , a beta optimization is performed and this predicts an optimized, stable, circular cross-section equilibrium with a beta that is 40% above the Troyon limit.

Additional information

Authors: TURNBULL A D, CENTRE DE RECHERCHES EN PHYSIQUE DES PLASMAS, ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (SWITZERLAND);TROYON F CENTRE DE RECHERCHES EN PHYSIQUE DES PLASMAS, ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (SWITZERLAND), CENTRE DE RECHERCHES EN PHYSIQUE DES PLASMAS, ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (SWITZERLAND)
Bibliographic Reference: 12TH EUROPEAN CONFERENCE ON CONTROLLED FUSION AND PLASMA PHYSICS, BUDAPEST (HUNGARY), SEPT. 2-6, 1985 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32317 ORA
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