Self-consistent description of L-H mode transition dynamics in tokamaks

摘要

A theoretical model of L-H transition in a tokamak, based on the self-consistent analysis of plasma transport and taking the suppression of anomalous transport by sheared poloidal plasma rotation and the establishment of a radial electric field due to non-ambipolar particle transport into account, is presented. The transition to an improved confinement regime for a plasma with or without suprathermal electron component is studied. A numerical simulation shows that this model adequately describes the main, experimentally observed features of L-H transition dynamics during electron cyclotron or lower hybrid heating. It is also shown that in certain conditions such a transition can be 'auto-oscillatory', which may be considered as an ELMs feature. The dependence of the localization region of the ELMs and their characteristics (frequency and magnitude) on the plasma parameters are investigated.