Studies of a Poloidal Divertor Reversed Field Pinch

J. S. Sarff, A. F. Almagri, S. Assadi, D. J. Den Hartog, R. N. Dexter, S. C. Prager, and  J. C. Sprott
Department of Physics, University of Wisconsin, Madison, Wisconsin, United States of America
(Manuscript received 15 July 1988, Final manuscript received 10 October 1988)


An attempt has been made to form a reversed field pinch (RFP) in a poloidal divertor configuration which positions the plasma far from a conducting wall. In this configuration, the plasma is localized within a magnetic separatrix formed by a combination of toroidal currents in the plasma and four internal aluminium rings. Plasmas were formed with a plasma current of ~135 kA, toroidal field reversal lasting ~1 ms, line averaged density of ~(l-2) X 1013 cm-3 and central electron temperature of ~50 eV, but a large asymmetry in the magnetic field (dB/B ~ 40%) set in at about the time when the toroidal field reversed at the wall. This behaviour might be expected on the basis of MHD stability analysis of a cylindrical plasma
bounded by a large vacuum region and a distant conducting wall. The symmetric equilibrium before the asymmetry develops and the asymmetry itself are described.

Ref: J. S. Sarff, A. Almagri, S. Assadi, D. J. Den Hartog, R. N. Dexter, S. C. Prager, and J. C. Sprott, Nuclear Fusion 29, 104-108 (1989)

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