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khalzov_sh_aug6.pdf2014-08-15 14:08:40Ivan Khalzov

Saturated stationary helical states with field reversal

Author: Ivan V Khalzov
Requested Type: Poster Only
Submitted: 2014-06-09 16:54:37

Co-authors: V.V. Mirnov

Contact Info:
University of Wisconsin-Madison
1150 University Av.
Madison, Wisconsin   53706
USA

Abstract Text:
Saturated stationary helical states with field reversal
in dissipative incompressible MHD*

I.V. Khalzov and V.V. Mirnov

University of Wisconsin-Madison and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Madison, WI, USA

We perform an analytical and numerical study of linear kink instability and nonlinear saturated stationary states with helical symmetry in viscoresistive incompressible MHD. The analysis is performed for the geometry of periodic cylinder relevant to RFPs. A screw pinch with uniform axial current and uniform axial magnetic field represents an exact equilibrium solution of the dissipative MHD. This equilibrium is considered as an initial stage of fast plasma relaxation. The final nonlinear stationary helical states are obtained as a result of evolution and saturation of the kink instability existing initially in the system. The resulting helical configurations are characterized by a finite pressure gradient and exhibit reversal of the axial magnetic field near the plasma edge. The current sustainment in this zone is provided by the stationary non-axisymmetric dynamo velocity field. This work is in continuation of our previous studies [1]. The results are discussed in the context of the analytical criterion [2] for helical states with field reversal and numerical results [3] devoted to the quasi-single helicity states (QSH) enhanced by helical perturbation of the edge radial magnetic field.

*This work is supported by the U.S. Department of Energy and the
National Science Foundation.

[1] I.V. Khalzov, V.V. Mirnov, and D.D. Schnack, Proc. of the 15th International RFP Workshop, October 10-12 (2011), Madison, Wisconsin, USA.
[2] D. Bonfiglio, D.F. Escande, P. Zanca, and S. Cappello, Nucl. Fusion, 51 063016 (2011).
[3] D. Bonfiglio, M. Veranda, S. Cappello, D.F. Escande, and L. Chacon, Phys. Rev. Lett., 111, 085002 (2013).

Characterization: 3.0,4.0

Comments:

Workshop on Exploratory Topics in Plasma and Fusion Research (EPR) and US-Japan Compact Torus (CT) Workshop
August 5-8, 2014
Madison, Wisconsin

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