Ion heating experiments using perpendicular neutral beam injection in the Large Helical Device

A perpendicular neutral beam (P-NB) injector was installed in the Large Helical Device (LHD) and utilized for high-power ion heating and measurement of the ion temperature (Ti) profile by charge exchange spectroscopy. Significant progress was achieved in ion heating experiments using P-NB, and a high Ti of 5.2 keV was achieved at the plasma center. A Ti peak profile with a steep gradient in the core region was observed, indicating an improved mode of ion transport. The enhancement of toroidal flow in the core region was observed with the Ti rise. Transport analysis shows improvement in anomalous transport in the core region, and the neoclassical transport remains unchanged when the high Ti is realized. (author)