Initial measurement of ultrafast charge exchange recombination spectroscopy on the EAST tokamak

Abstract

An ultra-fast charge exchange recombination spectroscopy (UF-CXRS) has been developed on EAST tokamak (Yingying Li et al 2019 Fusion Eng. Des. 146 522-525) to measure fast evolution of ion temperature and toroidal velocity. Here we report the preliminary diagnostic measurements after relative sensitivity calibration. The measurement results show a much higher temporal resolution compared with conventional CXRS benefiting from the usage of a prism-coupled, high-dispersion VPH transmission grating and a high-quantum efficiency, high-gain detector array. Utilizing the UF-CXRS diagnostic, the fast evolutions of the ion temperature and rotation velocity during a set of high-frequency small-amplitude ELMs are obtained on the EAST tokamak, which are then compared with the case of large-amplitude ELMs.