The effects of triangularity and main ion species on the inter-ELM profile evolution in ASDEX Upgrade

摘要

In high confinement mode (H-mode) plasmas the steep gradients at the plasma edge (called pedestal) are quasi-periodically destabilised by edge localised modes (ELMs). Since the pedestal strongly affects the global plasma performance, further understanding of the temporal approach towards the pedestal stability limit (also known as pedestal recovery) is needed to optimise plasma scenarios. Previous studies have shown different recovery timescales of the electron density n_e and temperature T_e pedestal in between ELM crashes [1]. In these experiments the n_e pedestal recovered first, while the T_e pedestal started to recover after the n_e pedestal was established. Gyrokinetic modelling attributed the recovery timescales to the domination of different turbulent modes [2]. In the phase of the n_e recovery trapped electron modes were found in the pedestal, whereas in the pre-ELM pedestal after the T_e recovery, especially on large scales, microtearing modes and kinetic-ballooning modes were dominant.