Control of Equilibrium Separatrix Shape on Field-Reversed-Configuration Plasmas

Equilibrium shape of a field-reversed-configuration plasma is controlled to maximize its poloidal flux. Plasma elongation is changed from 7.5 to 4.5 by adding a local field to the plasma due to the introduction of a control coil. The control field strength is about 10% of the confinement field. The plasma shape modifies while keeping its volume and the product of its poloidal flux and elongation constant. The poloidal flux is twice that of the uncontrolled plasma. Its flux confinement time also improved.