Abstract
In this paper, we elaborate the electric field excitation mechanism during the L–H transition in the JFT-2M tokamak. Using time derivative of the Poisson’s equation, models of the radial electric field excitation is examined. The sum of the loss-cone loss current and the neoclassical bulk viscosity current is found to behave as the experimentally evaluated radial current that excites the radial electric field. The turbulent Reynolds stress only plays a minor role. The wave convection current that produces a negative current at the edge can be important to explain the ambipolar condition in the L-mode.
Highlights
Comprehensive understanding of the L-H transition mechanism is one of the most important issues towards realization of the future controlled fusion reactors
For the models of the L-H transition, two of them are mainly treated, i.e., the non-ambipolar particle flux that enhances the radial charge separation and the micro-scale turbulence dynamics [6]. The former is originated by the independent kinetic properties of ions and electrons that are brought by geometrical effects of torus plasmas, including the direct loss-cone loss of the ions across the separatrix [2, 3] and the neoclassical flux of the ions [3, 7]
Reynolds stress are systematically and quantitatively examined, using a data set obtained with a heavy ion beam probe system
Summary
Comprehensive understanding of the L-H transition mechanism is one of the most important issues towards realization of the future controlled fusion reactors. For the models of the L-H transition, two of them are mainly treated, i.e., the non-ambipolar particle flux that enhances the radial charge separation and the micro-scale turbulence dynamics [6] The former is originated by the independent kinetic properties of ions and electrons that are brought by geometrical effects of torus plasmas, including the direct loss-cone loss of the ions across the separatrix [2, 3] and the neoclassical flux of the ions [3, 7].
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