Slow transition of energy transport in high-temperature plasmas

Abstract

A new slow transition process for energy transport in magnetically confined plasmas is reported. The slow transition is characterized by the change between two metastable transport conditions characterized by a weak and a strong electron temperature (Te) dependence of normalized heat flux. These two branches are found to merge at the critical Te gradient. In metastable transport, the derivative of normalized heat flux to the Te gradient, ∂(Qe/ne)/∂(- vTe), is positive, while it becomes negative during the transition phase. The time for the transition increases as the normalized Te gradient is increased and exceeds the transport time scale characterized by the global energy confinement time. © 2006 The American Physical Society.