Development of a multi-spectral extreme ultraviolet imaging diagnostics on the Experimental Advanced Superconducting Tokamak

A multi-spectral extreme ultraviolet imaging (MEUVI) diagnostics to measure impurity line emissions on the Experimental Advanced Superconducting Tokamak (EAST) is proposed and being developed to measure the electron temperature at the edge region. It makes use of multi-channel multilayers Schwarzschild telescope, coupled with a micro-channel plate (MCP) equipped with a P46 phosphor screen, and a high-speed camera with a CMOS sensor to image the selected line emissions, i.e., C IV lines (312.4 Å, 419.7 Å), W XLVI line (127 Å), Ne VIII lines (88.1 Å, 103 Å), and Ne VII Line (465.2 Å), at the edge region in two dimensions with high spatial and temporal resolutions simultaneously. The MEUVI diagnostics is installed on the EAST horizontal J port to monitor plasma and first imaging data is obtained during the commissioning of the system in the 2024 experiment campaign. It is in good agreement with that measured by the traditional extreme ultraviolet (EUV) spectrometer. In addition, the electron temperature derived from the MEUVI data is higher than that given by the Helium beam emission (He-BES) spectroscopy system since the Ne VIII emission is mainly located inside the last closed surface region. However, the tendency of the evolution of the electron temperature is consistent each other, which are given by these two systems. These results verify that the MEUVI diagnostics can work as a potential tool for the measurement of edge plasma temperature and monitoring of impurities.