Results 221 to 230 of about 694,012 (248)

Probabilistic Nature in L/H Transition

Journal of the Physical Society of Japan, 1999
Statistical picture for an excitation of a plasma transition is examined, which occurs in a strongly turbulent state. The physical picture of transition phenomena is extended to include the statistical variances. The dynamics of the plasma density and turbulent-driven flux is studied with hysteresis nature in the flux-density relation.
Shinichiro Toda, Sanae-I. Itoh, Masatoshi Yagi, Kimitaka Itoh, Atsushi Fukuyama   +4 more
openaire   +1 more source

L‐H Transition Experiments in TJ‐II

Contributions to Plasma Physics, 2010
AbstractIn the TJ‐II stellarator, L‐ to H‐mode transitions are achieved under NBI heating conditions when operating with lithium coated walls. Several magnetic configurations have been explored in order to study the influence of the rotational transform in the transition.
T. Estrada, E. Ascasíbar, T. Happel, C. Hidalgo, E. Blanco, R. Jiménez‐Gómez, M. Liniers, D. López‐Bruna, F.L. Tabarés, D. Tafalla   +9 more
openaire   +1 more source

L-H transition in the mega-amp spherical tokamak.

Physical review letters, 2002
H-mode plasmas have been achieved on the MAST spherical tokamak at input power considerably higher than predicted by conventional threshold scalings. Following L- H transition, a clear improvement in energy confinement is obtained, exceeding recent international scalings even at densities approaching the Greenwald density limit.
Akers, R.J., Counsell, G.F., Sykes, A., Appel, L.C., Arends, E.R., Byrom, C., Carolan, P.G., Conway, N.J., Cunningham, G., Dnestrovskij, A., Dnestrovskij, Y.N., Field, A.R., Fielding, S.J., Gryaznevich, M., Helander, P., Kirk, A., Korsholm, S., Martin, R., Meyer, H., Nightingale, M.P. S., Roach, C.M., Shevchenko, V., Torunianski, M., Walsh, M.J., Warrick, C.D.   +24 more
openaire   +2 more sources

L–H transition in tokamak plasmas: 1.5-D simulations

Journal of Nuclear Materials, 1999
Abstract 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., Pacher, G., Igitkhanov, Y., Pacher, H., Pinches, S., Pogutse, O., Sugihara, M.   +6 more
openaire   +2 more sources

Transport Modeling of L/H Transition in Tokamaks

Fusion Technology, 1995
In order to study the particle transport and the mechanism of the L/H transition in tokamaks, a one-dimensional transport code which describes the toroidal and poloidal plasma rotation as well as the radial electric field has been developed. The neoclassical transport, turbulent transport and ion orbit loss are included.
Y. Fuji, K. Itoh, A. Fukuyama, S.-I. Itoh   +3 more
openaire   +1 more source

Statistical theory of L H transition in tokamaks*

Plasma Physics and Controlled Fusion, 2003
A statistical model for the bifurcation of the radial electric field Er is developed in view of describing L–H transitions of tokamak plasmas. Noise in micro-fluctuations is shown to lead to random changes of Er, if a deterministic approach allows for more than one solution.
S-I Itoh, K Itoh, S Toda
openaire   +1 more source

Understanding L–H transition in tokamak fusion plasmas

Plasma Science and Technology, 2017
This paper reviews the current state of understanding of the L–H transition phenomenon in tokamak plasmas with a focus on two central issues: (a) the mechanism for turbulence quick suppression at the L–H transition; (b) the mechanism for subsequent generation of sheared flow.
Guosheng XU, Xingquan WU
openaire   +1 more source

Multi-shell transport model for L-H transition

Physics of Plasmas, 2017
A coupled model of transport, turbulence, and mesoscale flows is proposed, including turbulence spreading. The model consists of transport equations for plasma density and pressure coupled to a shell model of drift wave turbulence, which incorporates coupling to mesoscale flows via disparate scale interactions.
Berionni, Vincent, Morel, Pierre, Gürcan, Özgür   +2 more
openaire   +2 more sources

`Hidden' variables affecting the L-H transition

Plasma Physics and Controlled Fusion, 1998
Recent 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 ...
openaire   +1 more source

Ion collisionality and L–H transition in tokamaks

Physics of Fluids B: Plasma Physics, 1993
When the previous H-mode theory [K. C. Shaing and E. C. Crume, Jr., Phys. Rev. Lett. 63, 2369 (1989)] is extended to include a bi-Maxwellian ion distribution with both cold and hot ion components to model the effects of the non-Maxwellian distribution, the collisionality of the cold ions ν*ic becomes an irrelevant bifurcation parameter, as it is for ...
K. C. Shaing, P. J. Christenson
openaire   +1 more source