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Electron and impurity ion density profiles have been controlled by using tangential and perpendicular neutral beams for plasma heating in a stellarator/heliotron for the first time. Reduced anisotropy of stored energy for energetic ion En?/Enjj has resulted in an inward electron and impurity transport, forming a core electron density peaking. Increased anisotropy leads to a flat or hollowed electron density profile with an impurity exhaust in a core region [Yoshinuma et al., Nucl. Fusion 49, 062002 (2009)]. A high confinement state of particles in LHD has yet to be achieved, except for a temporal state of an electron density peaking created by a pellet injection. As a pioneering and crucial research result, the operation of energetic ion anisotropy by neutral beams has newly demonstrated that the direction of the radial transport of bulk and impurity ions can be controlled. At the same time, the overall plasma performance rises in neutron flux and stored energy. On the other hand, the increase in the anisotropy flattens the density profile. This new finding holds promise for a control knob of nuclear fusion reactors to enhance fusion power output.

The neutron emission profile of deuterium plasma in the Large Helical Device was measured with a multi-sightline vertical neutron camera under various magnetic field strength conditions. It was found that the line-integrated neutron emission profile shifts outward in the co-neutral beam (NB) case and inward in the counter NB case. Here, co- and counter directions correspond to enhance and reduce the poloidal magnetic field directions, respectively. The shift becomes more significant when the magnetic field decreased in strength. The experimentally obtained neutron emission profile was compared with the orbit-following models simulated through the DELTA5D code. The calculated neutron emission profiles vary according to the magnetic field strength because of the change of beam ion orbit and the slowing down due to the plasma parameter changes. Although a relatively narrow profile was obtained in the calculations at the inboard side for the co-NB case in the relatively low field condition, the profiles obtained through calculation and experiment were almost qualitatively aligned.