Inter-ELM Fluctuations and Flows and their evolution when approaching the density limit in the ASDEX Upgrade tokamak

摘要

High performance regimes (H-mode) are reached through the spontaneous formation of a transport barrier resulting from the shear-flow suppression of turbulence. The steep edge density and temperature gradients allow for large pedestal top temperature and density, thought to be necessary for ITER to achieve its fusion power targets. However these steep gradients drive instabilities such as edge localized modes (ELMs), which appear as repetitive collapses of the edge pressure profile that may release unacceptable heat loads on the machine walls. Between ELMs, temperature and density profiles build up again on different time scales [1,2,3], raising the question of which transport mechanisms determine the profile evolution until the next ELM [4].