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

Nuclear Fushion

article

C. Bourdelle¹  L. Chôné¹  N. Fedorczak¹  X. Garbet¹  P. Beyer²  J. Citrin¹  E. Delabie⁴  G. Dif-Pradalier¹  G. Fuhr²  A. Loarte⁵  C.F. Maggi⁶  F. Militello⁶  Y. Sarazin¹  L. Vermare⁷ 

[1] CEA;Aix-Marseille Université;FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research;Oak Ridge National Laboratory;ITER Organization;Culham Centre for Fusion Energy;Laboratoire de Physique des Plasmas

关键词: plasma physics;    L H transition;    tokamak;   

DOI  :  10.1088/0029-5515/55/7/073015

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

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 derivedT _th are tested versus magnetic field, density, effective charge. Various robust experimental observations are reproduced, in particularT _th increases with magnetic fieldBand increases with density below the density roll-over observed on the power threshold.

【 授权许可】

Unknown