Neoclassical tearing mode saturation in periodic current sheets

Journal Article · Tue Apr 15 04:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2901193· OSTI ID:21120227

Militello, F ^[1]; Ottaviani, M ^[2]; Porcelli, F ^[1]

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1. Burning Plasma Research Group and Politecnico di Torino, 10129 Torino (Italy)
2. Association Euratom CEA, CEA/DSM/IRFM, Cadarache, 13108 Saint-Paul-lez-Durance (France)

The saturation of Neoclassical Tearing Mode islands in a periodic slab configuration is investigated. Several theoretical models, all based on a generalization of Rutherford's procedure, that aim at reducing the complete system to a single equation of the magnetic island width, are compared against numerical simulations. When the effects of the bootstrap current and of the second derivative of the equilibrium current profile are included, the numerical saturation levels are well matched with the predictions of this equation in a wide region of the stability diagram. However, the numerical results diverge from the standard theory when evaluating the threshold for nonlinear destabilization, since the theoretical value appears to be strongly conservative. In other words, the standard generalization of Rutherford's equation is not able to capture the minimum value of the linear stability parameter and of the island width such that below them the Neoclassical Tearing Mode is always suppressed. To correct this discrepancy, a new theoretical model in which the transverse propagation of the island affects the bootstrap current term is proposed.

• OSTI ID: 21120227
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOOTSTRAP CURRENT
DIAGRAMS
EQUATIONS
MAGNETIC ISLANDS
MAGNETIC RECONNECTION
NEOCLASSICAL TRANSPORT THEORY
NONLINEAR PROBLEMS
PERIODICITY
STABILITY
TEARING INSTABILITY