STUDY OF L–H TRANSITION AND PEDESTAL WIDTH BASED ON TWO-FIELD BIFURCATION AND FIXED POINT CONCEPTS

Acta Polytechnica

Thawatchai Onjun²  Boonyarit Chatthong¹ 

[1] School of Manufacturing and Mechanical Engineering, Sirindhorn International Institute of Technology, Thammasat University

关键词: plasma;    tokamak;    fusion;    L–H transition;    bifurcation;   

DOI  :  

来源: Czech Technical University in Prague, Faculty of M

【 摘 要 】

The L–H transition in magnetic confinement plasmas is investigated on the basis of concepts of two-field bifurcation and fixed-point stability. A set of heat and particle transport equations with both neoclassical and anomalous effects included is used to study ETB formation and also pedestal width and dynamics. It is found that plasmas can exhibit bifurcation where a sudden jump in the gradients can be achieved at the transition point corresponding to the critical flux. Furthermore, it is found that the transport barrier expands inward, whereby the radial growth of the pedestal initially appears to be superdiffusive but later slows down and stops. In addition, the time of barrier expansion is found to be much longer than the time that plasma takes to evolve from L-mode to H-mode. A sensitivity study is also performed, in which the barrier width is found to be sensitive to various parameters, e.g. heating, transport coefficients and suppression strength.

【 授权许可】

Unknown