Spatially-resolved flat-field soft X-ray spectrometer on experimental advanced superconducting tokamak

• Published in: Fusion engineering and design Vol. 88; no. 11; pp. 3072 - 3077
• Main Authors: Shen, Yongcai, Lu, Bo, Du, Xuewei, Li, Yingying, Fu, Jia, Wang, Fudi, Zhang, Hongming, Xiong, Yanwei, Wang, Qiuping, Shi, Yuejiang, Wan, Baonian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2013
• Subjects: Charge coupled devices; EAST; Flat field; Impurity emission; Soft X-ray spectrometer; 52.70.Kz; Flat field; 33.20.Ni; 52.25.Vy; Soft X-ray spectrometer; Impurity emission; EAST
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2013.08.003

•A soft X-ray spectrometer was successfully developed on EAST tokamak.•The system can observe impurity line emissions with good spectral resolution.•Typical line emission measurements from the EAST tokamak were illustrated. A space- and time-resolved flat-field soft X-ray spectrometer with the wavelength range of 1–13nm has been developed to study impurity behavior on the Experimental Advanced Superconducting Tokamak (EAST). Using an entrance slit, a varied line spacing grating (2400grooves/mm at the grating center), and a charged coupled device (CCD) system, time evolution of profiles of impurity line emissions were recorded. The spectral resolution of the spectrometer is 0.006nm at 5nm when the width of entrance slit is set at 0.03mm. The best spatial resolution obtained is 24.5mm with the height of slit at 1.0mm. The spectrometer is placed 8000mm away from the plasma center and the observed spatial range covers 0–450mm from the equatorial plane of EAST. The first experimental results were obtained from the recent EAST campaign. The system was shown to be capable of observing spectral lines from both intrinsic low-Z impurities (C, O, et al.) and highly ionized medium- and high-Z impurities (Fe, Cr, Ni, Cu, et al.). Spectral lines from the full wavelength range (1–13nm) can be obtained by moving the position of the CCD. Spectra with the wavelength intervals of 1–2nm show strong metal lines for H-mode discharges. Time evolutions of C VI (3.373nm) and O VIII (1.897nm) lines are presented and detail analysis is performed combining electron density intensity, Dα and soft X-ray and extreme ultraviolet (XUV) radiation intensities. Evolutions of profiles of C VI (3.373nm) and O VIII (1.897nm) at core plasma were also shown, indicating that the spectrometer can be applied for impurity transport studies,