Speaker
YooSung Kim
(Department of Nuclear Enigneering)
Description
Helium transport study is essential in burning plasma to prevent fuel dilution from the helium ash accumulation. Charge exchange spectroscopy (CES) is widely used to measure impurity density as well as toroidal rotation and ion temperature. Single-handed CES system have a low accuracy in impurity density measurement due to the large errors in absolute intensity calibration and neutral beam modelling calculation. For this reason, the combined system of charge exchange spectroscopy and beam emission spectroscopy (BES) has been proposed to measure impurity density with only relative intensity calibration of the spectrometer. Doppler Shifted Hα line (rest wavelength at 656.3 nm) for BES and HeII (n=4-3 468.6 nm) for CES are used in the hydrogen discharge with puffing a small amount of helium in VEST. A dichroic beam splitter is used to measure CES and BES signals simultaneously with sharing the same observation and transmission components which include the line of sight, lenses, optical fiber bundles. High spectral resolution spectrometersuitable for the VEST is carefully designed based on the transmission grating with high diffraction efficiency. Multi-chord sightlines in toroidal view have been chosen to have a good spatial resolution from the edge to the core. In this paper, we present a detailed design of the combined system of CES and BES for VEST, with consideration of the estimated spectrum intensities for active signals as well as background noises.
Co-authors
Kihyun Lee
(Department of Nuclear Enigneering, Seoul National University, Seoul, South Korea)
Kyoung-Jae Chung
(Department of Nuclear Enigneering, Seoul National University, Seoul, South Korea)
Soo-Ghee Oh
(Center for Advanced Research in Fusion Reactor Engineering, Seoul National University, Seoul, South Korea)
Y.S. Hwang
(Department of Nuclear Enigneering, Seoul National University, Seoul, South Korea;Center for Advanced Research in Fusion Reactor Engineering, Seoul National University, Seoul, South Korea)
YooSung Kim
(Department of Nuclear Enigneering, Seoul National University, Seoul, South Korea)
Yue-Jiang Shi
(Department of Nuclear Enigneering, Seoul National University, Seoul, South Korea)
