Fusion Science and Technology / Volume 58 / Number 1 / July 2010 / Pages 131-140
Chapter 3. Confinement and Transport / Special Issue on Large Helical Device (LHD)
On the Large Helical Device (LHD), improved confinement of fast ions by moving the magnetic axis location inward is theoretically predicted. This improvement is observed significantly in the fast-ion tail formation during the experiments of ion cyclotron range of frequency heating. The fast-ion loss effect on the tail formation is 10 times more significant in the standard configuration than in the inwardly shifted configurations. The superiority is also confirmed by the comparison of steady-state fast-ion spectra for the neutral beam (NB)-heated plasmas and by the flux decay of fast neutrals after the short-pulse injection of radial NB.