Dynamo-free plasma in the reversed-field pinch: Advances in understanding the reversed-field pinch improved confinement mode

Journal Article · Sun May 15 00:00:00 EDT 2005 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.1883666· OSTI ID:20736583

Anderson, J K; Adney, J; Almagri, A; Blair, A; Cengher, M; Chapman, B E; Choi, S; Craig, D; Hartog, D.J. den; Ebrahimi, F; Ennis, D; Fiksel, G; Forest, C B; Goetz, J; Holly, D; Hudson, B; Kaufman, M; Lovell, T; McCollam, K; Mirnov, V V ^[1]

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1. University of Wisconsin, Madison, Wisconsin (United States) and the Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas (US)

Generation and sustainment of the reversed field pinch (RFP) magnetic configuration normally relies on dynamo activity. The externally applied electric field tends to drive the equilibrium away from the relaxed, minimum energy state which is roughly described by a flat normalized parallel current density profile and is at marginal stability to tearing modes. Correlated fluctuations of magnetic field and velocity create a dynamo electric field which broadens the parallel current density profile, supplying the necessary edge current drive. These pervasive magnetic fluctuations are also responsible for destruction of flux surfaces, relegating the standard RFP to a stochastic-magnetic transport-limited device. Application of a tailored electric field profile (which matches the relaxed current density profile) allows sustainment of the RFP configuration without dynamo-driven edge current. The method used to ascertain that a dynamo-free RFP plasma has been created is reported here in detail. Several confinement improvements during the accompanying periods of low magnetic fluctuations are observed. Namely, the magnetic fluctuation level is reduced to the point where stochastic-magnetic transport is no longer the dominant process in the core and nested flux surfaces are restored in the core of the dynamo-free RFP.

• OSTI ID: 20736583
• Journal Information: Physics of Plasmas, Vol. 12, Issue 5; Other Information: DOI: 10.1063/1.1883666; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOUNDARY LAYERS
FLUCTUATIONS
PLASMA
PLASMA DENSITY
REVERSE-FIELD PINCH
TEARING INSTABILITY