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`Hidden' variables affecting the L-H transition
Plasma Physics and Controlled Fusion, 1998Recent progress in experimental investigations, related to the determinant variables of the L-H transition, is reviewed in this paper. In particular, it is put forward that the `wall effect', which often produces spurious contributions to the various parametric dependences of the H-mode threshold power, may be an embodiment of the atomic processes ...
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Critical assessment of ion loss mechanisms for L-H transition
Plasma Physics and Controlled Fusion, 2000Monte Carlo ion simulation of the tokamak edge, based on the neoclassical radial current balance, shows that a considerable E×B shear, relevant for turbulence suppression, can be generated by orbit losses. In contrast to earlier orbit loss models, no spontaneous bifurcation of the radial electric field Er is found. However, a bifurcation and a solitary
Kiviniemi, T. +4 more
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L–H transition in tokamak plasmas: 1.5-D simulations
Journal of Nuclear Materials, 1999Abstract Time-dependent theoretical models have been implemented in a 1.5-D transport code to describe the operational boundaries (L–H transition, ballooning limit) in terms of edge parameters. The width of the H-mode transport barrier (F. Wagner et al., Phys. Rev. Lett.
Janeschitz, G. +6 more
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One of the most beautiful phenomena we observe in tokamaks is the transition between L and H-mode, a clear phase transition. Here we present and discuss results from dedicated L-H transition experiments at JET-ILW [ER Solano et al, Nuclear Fusion 63 (11), 112011, 2023]. Uniquely, we studied the power threshold in plasmas composed of pure Tritium, to be
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Electron density evolution after L–H transitions and the L–H/H–L cycle in ASDEX Upgrade
Nuclear Fusion, 2012Abstract The development of the electron density profile and its dependences after the L–H transition have been investigated. Only electron cyclotron resonance heated H-modes have been analysed to exclude core particle fuelling. While the density gradient in the edge transport barrier increases significantly after the L–H transition, the
Willensdorfer, M. +13 more
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Transport modelling of L - H transition and barrier formation
Plasma Physics and Controlled Fusion, 1996The mechanism of L - H transition and transport barrier formation is studied by the use of a one-dimensional transport code including plasma rotation and radial electric field. Particle transport simulation with a fixed temperature profile has indicated that the density profile is quite sensitive to the edge plasma temperature.
A Fukuyama +4 more
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Probabilistic theory of the L-H transition and causality
Plasma Physics and Controlled FusionAbstract The low-to-high confinement (L-H) transition is critical for understanding plasma bifurcations and self-organization in high-temperature fusion plasmas. This paper reports a probabilistic theory of the L-H transition, in particular, a probability density function of power threshold Qc for the first time ...
Eun-jin Kim, Abhiram Anand Thiruthummal
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Warm-ion drift Alfvén turbulence and the L-H transition
Plasma Physics and Controlled Fusion, 1998Computations of fluid drift turbulence treating ions and electrons on equal footing, including both temperatures, are conducted in a model toroidal geometry. The resulting `ion mixing mode' turbulence bears features of both electron drift-Alfven and ion temperature gradient turbulence, and nonlinear sensitivity to the relative strengths of the density ...
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On revisited models of L-H transition for tokamak
2008info:eu-repo/semantics ...
Negrea, Marian +2 more
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