Study on Fast Deuteron Diagnostics Method Using Fast ³He Visible Spectra in the Large Helical Device Deuterium Plasma

Fast ion diagnostic is one of the most crucial plasma diagnostics for nuclear fusion investigation. A new diagnostic method for fast ions has been proposed using visible spectra of 3He produced by a deuteron-deuteron reaction. This diagnostic method has a better energy resolution than methods using neutron/γ-ray and is superior to conventional spectroscopy in measuring high energy (MeV order) ions. This diagnostic method has been predicted using numerical analysis for ITER, but no verification experiments have been performed yet. In this study, we examined the measurability of this diagnostic method in the large helical device (LHD) deuterium plasma. Although very dependent on the measurement geometry and the spectrometer performance, it may be possible to measure the fast 3He visible spectrum.