Observation of deuterium molecule emission spectra under an active feedback control of H-mod plasma divertor detachment experiment on the EAST tokamak**Project supported by the National Natural Science Foundation of China (Grant No. 11805234).

Abstract

Based on neon gas puffing, an active feedback control of H-mod plasma divertor detachment experiment was successfully operated on the EAST tokamak. During the feedback control discharge, the plasma was detached by puffing neon gas and the strike point splitting phenomenon on divertor target was also clearly observed by divertor probes diagnostic. In boundary region, many neutral particle processes (atom and molecule) were happened and accompanied by their emission spectra under the detachment discharge. By studying these emission spectra, it is helpful for us to understand the role of atoms and molecules in boundary recycling, which is important for studying the physical mechanism of divertor detachment. For the Fulcher-α system (, D2 emission spectra in the range from 601 nm to 606 nm were observed, identified and fitted in the detachment experiment for the first time on the EAST, and the spectra in the Q(0–0) band ( in the Q branch of the Fulcher-α system were used for detailed analysis to acquire the boundary region temperature Te (below 5 eV), which could not be provided very well by other diagnostics on the EAST. An electronic version deuterium molecular spectral line database was established to identify the spectral lines and a multi-peak fitting program was developed to fit and analyze the observed spectra.