Ion-Bernstein-Wave Heating in the JIPPT-II-U Tokamak Plasma

Ion-Bernstein-wave heating is investigated in the JIPPT-II-U tokamak plasma, ${\overline{n}}_{e}\ensuremath{\simeq}1.5\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, ${T}_{e0}\ensuremath{\simeq}700$ eV, and ${T}_{i0}\ensuremath{\simeq}300$ eV for ${P}_{\mathrm{rf}}\ensuremath{\lesssim}100$ kW. When the $\frac{3}{2}{\ensuremath{\Omega}}_{\mathrm{H}}$ layer is placed near the plasma minor axis, the bulk-hydrogen-ion temperature shows a significant rise, $\ensuremath{\Delta}{T}_{i\ensuremath{\perp}}<~700$ eV and $\ensuremath{\Delta}{T}_{i\ensuremath{\parallel}}<~300$ eV. The ion-heating dependence on the magnetic field and rf power suggests a presence of a direct bulk-hydrogen heating mechanism at $\ensuremath{\omega}\ensuremath{\simeq}\frac{3}{2}{\ensuremath{\Omega}}_{\mathrm{H}}$.