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Article Dans Une Revue Nuclear Fusion Année : 2015

L to H mode transition: parametric dependencies of the temperature ă threshold

Résumé

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

Dates et versions

hal-01465042 , version 1 (10-02-2017)

Identifiants

Citer

C. Bourdelle, L. Chone, Nicolas Fedorczak, Xavier Garbet, Ă P. Beyer, et al.. L to H mode transition: parametric dependencies of the temperature ă threshold. Nuclear Fusion, 2015, 55 (7), ⟨10.1088/0029-5515/55/7/073015⟩. ⟨hal-01465042⟩
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