L to H mode transition: Parametric dependencies of the temperature threshold

Bourdelle, C.; Chone, L.; Fedorczak, N.; Garbet, Xavier; Beyer, P.; Citrin, J.; Fuhr, G.; Loarte, A.; Maggi, C. F.; Militello, F.; Sarazin, Y.; Vermare, L.; Delabie, E.; Dif-Pradalier, G.

doi:10.1088/0029-5515/55/7/073015

L to H mode transition: Parametric dependencies of the temperature threshold

Journal Article · Mon Jun 15 00:00:00 EDT 2015 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/55/7/073015· OSTI ID:1263860

Bourdelle, C. ^[1]; Chone, L. ^[2]; Fedorczak, N. ^[1]; Garbet, Xavier ^[1]; Beyer, P. ^[3]; Citrin, J. ^[4]; Fuhr, G. ^[3]; Loarte, A. ^[5]; Maggi, C. F. ^[6]; Militello, F. ^[6]; Sarazin, Y. ^[1]; Vermare, L. ^[7]; Delabie, E. ^[8]; Dif-Pradalier, G. ^[1]

CEA, IRFM, Saint-Paul-lez-Durance (France)
CEA, IRFM, Saint-Paul-lez-Durance (France); Aix-Marseille Univ., CNRS, Marseille Cedex (France)
Aix-Marseille Univ., CNRS, Marseille Cedex (France)
CEA, IRFM, Saint-Paul-lez-Durance (France); FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Nieuwegein (The Netherlands)
ITER Organization, Saint Paul Lez Durance (France)
Culham Centre for Fusion Energy, Abingdon (United Kingdom)
Ecole Polytechnique, Palaiseau (France)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

The L to H mode transition occurs at a critical power which depends on various parameters, such as the magnetic field, the density, etc. Experimental evidence on various tokamaks (JET, ASDEX-Upgrade, DIII-D, Alcator C-Mod) points towards the existence of a critical temperature characterizing the transition. This criterion for the L-H transition is local and is therefore easier to be compared to theoretical approaches. In order to shed light on the mechanisms of the transition, simple theoretical ideas are used to derive a temperature threshold (T_th). They are based on the stabilization of the underlying turbulence by a mean radial electric field shear. The nature of the turbulence varies as the collisionality decreases, from resistive ballooning modes to ion temperature gradient and trapped electron modes. The obtained parametric dependencies of the derived T_th are tested versus magnetic field, density, effective charge. Furthermore, various robust experimental observations are reproduced, in particular T_th increases with magnetic field B and increases with density below the density roll-over observed on the power threshold.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE Office of Science (SC)

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 1263860

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 7 Vol. 55; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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L to H mode transition: Parametric dependencies of the temperature threshold

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