SELF-CONSISTENT DESCRIPTION OF L-H MODE TRANSITION DYNAMICS IN TOKAMAKS

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 establ ishment of a radial electric field due to non-ambipolar particle trans port into account, is presented. The transition to an improved confine ment regime for a plasma with or without suprathermal electron compone nt is studied. A numerical simulation shows that this model adequately describes the main, experimentally observed features of L-H transitio n dynamics during electron cyclotron or lower hybrid heating. It is al so shown that in certain conditions such a transition can be 'auto-osc illatory', which may be considered as an ELMs feature. The dependence of the localization region of the ELMs and their characteristics (freq uency and magnitude) on the plasma parameters are investigated.