First Measurement of VUV Spectroscopy Using 1 m Normal Incidence Spectrometer on HL-2A

A 1 m vacuum ultraviolet (VUV) spectrometer with temporal and spatial resolution was developed for impurity study of HL-2A tokamak. The instrument is equipped with two concave gratings blazed at 80 nm and 150 nm, respectively, and a windowless back-illuminated charge coupled device (CCD) detector of 256 x 1024 pixels. The total wavelength coverage of spectrometer is 30 ∼ 320 nm with a spectral resolution of 0.015 nm at a width of entrance slit of 10 μm. A portion of this range is observed during a plasma discharge with a spectral range of 20 nm. The minimum integration time of the detector system is about 6.7 ms for each frame in a full binning mode. Using a space-resolved slit located between the entrance slit and the grating a radial profile on the vertical direction with a range of 400 mm can be obtained. The primary results were successfully obtained with high signal-to-noise ratio and good spectral resolution, which demonstrated the instrument functions very well.