A model for electron transport barriers in tokamaks, tested against experimental data from RTP

摘要

Recent experiments in the RTP tokamak have shown that the electron temperature, T_e, profile in EC heated L mode discharges can have only a small number of distinct profle shapes, Depending on the location of the additional heating. The sharp transitions between the profile shapes Are associated with the loss or grain of a low rational q surface. These observations suggest that the Electron thermal diffusivityχ_e is a direct function of the safety factor q, with alternating layers of low And highχ_e. It is shown that such a model not only excellently describes the distinct profile shapes But also predicts other, observed but so far unexplained, phenomena, such as sharp off-axis maxima Of T_e observed with off-axis heating at specific radii.