Development Of EAST Rapid Vacuum Ultraviolet Spectrum Diagnostic System And Analysis Of Impurity Spectrum

The high impurity content in fusion plasma will lead to the sharp increase of core radiation,reduce energy constraints and even lead to plasma instability or even fracture.How to control the impurity content in the plasma is a major challenge for the fusion reactor to achieve high performance and stable operation in the future.It is very important to measure and analyze the impurity radiation behavior for controlling the impurity content and improving the plasma confinement performance.The dominant wavelength range of edge impurity emissions moves from the visible range to the vacuum ultraviolet range,With heating power increasing in EAST.The measurements of existing visible spectroscopies are not enough for the impurity transport study in the highparameters plasma in EAST.Therefore,a vacuum ultraviolet spectroscopic diagnostic system is recently developed to study impurity emissions in the edge region.One Saya-Namioka spectrometer is used for the vacuum ultraviolet spectroscopic diagnostic system.The vacuum ultraviolet spectrometer is equipped with a holographic concave grating with groove density of 600 g/mm.Impurity line emissions can be observed in the wavelength range of 50 nm to 700 nm,covering both vacuum ultraviolet and visible ranges.The observed vertical range is from Z =-350 nm to 350 nm.The minimum sampling time can be set to 5 ms.During the 2019 EAST experimental campaign,the vacuum ultraviolet spectroscopy has been used to monitor the edge impurity emission.Impurity spectra are identified for multi impurity species.Time evolution of different line radiation intensity of C_IV(154.8nm)and Fe_II(235nm)are analyzed to verify the measurement of vacuum ultraviolet spectroscopic diagnostic system and plasma parameter.Spectral measurement of impurity tungsten(W)is essential to study impurity transport.Therefore,the X-ray crystal spectrometer(XCS)on EAST is used to measure the line spectra from high-ionized W ions.On EAST,both poloidal XCS(PXCS)and tangential XCS(TXCS)have been developed to measure the plasma temperature as well as rotation velocity.Recently,He-like and H-like argon spectra have also been obtained using two-crystal setup.W lines are identified in this study.Through carefully analysis,W lines of 3.9336 ?,3.9321 ? and 3.664 ? are found to be diffracted by He-like or H-like crystals.The ion temperature from W lines is entirely consistent with that from Ar line spectra.In this study,the VUV system has been developed on EAST.The edge impurity spectrum has been measured and analyzed.Based on high-resolution XCS,the high ionized tungsten line in the core was studied,and the W XLV(3.664 ?)was identified.This study is meaningful for further study of physical mechanism of impurity transport in EAST and impurity controlling method.