Beam acceleration by heating in the second-harmonic ion cyclotron range of frequency (ICRF) in combination with heating by hydrogen neutral beam injection (NBI) was investigated in the JT-60 tokamak. The energy spectra of the accelerated fast ions were measured by a charge exchange neutral energy analyser whose line of sight was intersected by specific beam lines in the plasma core in order to obtain the required information. The dependences of the tail ion temperature on various parameters (electron density, NBI power and the toroidal phasing of the antenna) were examined. Optimized conditions for beam acceleration were evaluated. For combined ICRF heating and NBI heating, an incremental energy confinement time of 210 ms was achieved, which was three times higher than that obtained with NBI heating alone or with ICRF heating alone. This improvement of the energy confinement during combined NBI and ICRF heating can be explained by a build-up of the fast ions accelerated by the ICRF wave. The scaling of the incremental energy confinement time during combined ICRF+NBI heating was obtained.
ICRF加熱と水素中性粒子ビーム入射（NBI）による加熱を組み合わせた際の、第二高調波イオンサイクロトロン周波数帯（ICRF）におけるビーム加速をJT-60トカマクで研究した。加速された高速イオンのエネルギー分布は、プラズマ中心部において特定のビームラインと交差する視線を有する荷電交換中性粒子エネルギー分析器を用いて測定し、必要な情報を得た。高速イオン温度の各種パラメータ（電子密度、NBIパワー、アンテナのトロイダル位相）への依存性を調べた。ビーム加速の最適条件を評価した。ICRF加熱とNBI加熱を組み合わせた場合、増分エネルギー閉じ込め時間は210 msに達し、これはNBI加熱単独またはICRF加熱単独の場合の3倍に相当した。ICRF加熱とNBI加熱を組み合わせた際のエネルギー閉じ込めの改善は、ICRF波によって加速された高速イオンの蓄積によって説明できる。ICRF+NBI複合加熱時の増分エネルギー閉じ込め時間のスケーリング則を得た。