Confinement loss in JET ELMy H-modes

摘要

A spontaneous transition of the plasma from the type I ELM regime to a lower confinement mode is observed in JET ELMy H-modes with both the Mark II[1,2] adn the Gas BOx divertors. IT was recognised already in Mark II that this transition is associated iwth opeation too close to the L-H power threshold, and that it is possible to maintain the Type I ELM regime in steady state with input power in excess of twice the L-H threshold power. In Mark II, the occurrence of the loss of confinement constrained the effort to maximise the fusion power in JET deuterimum plasmas by operating at high plasma current.