First results of upgraded beam emission spectrometer on EAST

Abstract

The beam emission spectroscopy (BES) system that shares the collection optics with the core charge exchange recombination spectroscopy (cCXRS) has recently been upgraded on EAST. The enhanced system aims at the simultaneous measurements of the neutral beam emission from the co-current and counter-current neutral beam injection (NBI) as well as the active charge exchange line (Dα, n = 3→2, 656.1 nm) from the interaction of the main ions and the injected neutral beam. The operating spectral band of the system is 656.1 ± 6 nm, with respect to the maximum Doppler shift and stark splitting induced by the highest energy of 80 keV for deuterium beam. Strong edge Dα line is effectively suppressed by one curved chromate strip (˜3% transmission and ˜83 μm width) on the fused silica. Main ion Dα emission and beam emission spectra are acquired simultaneously without any saturation of the signal on the detector. In this paper, an overview of the upgraded spectrometer will be shown and the first experimental results are presented.