Understanding energetic particle (EP) confinement is one of the critical issues in realizing fusion reactors. In stellarator/helical devices, the research on EP confinement is one of the key topics to obtain better confinement by utilizing the flexibility of a 3D magnetic field. A study of EP transport in the Large Helical Device (LHD) has been performed by means of escaping EP diagnostics in hydrogen plasma operation. By starting deuterium operation of the LHD, the confinement study of EPs has progressed remarkably using newly developed comprehensive neutron diagnostics providing information for EPs confined in the core region. The total neutron emission rate (Sn) increases due to the relatively low deviation of the beam ion orbit from the flux surface with the inward shift of the magnetic axis. The Sn has a peak around the electron density of 2 × 1019 m−3 to 3 × 1019 m−3, as predicted. It is found that the fraction of beam–beam components in Sn is evaluated to be approximately 20% by the Fokker–Planck models TASK/FP in the plasma with both co- and counter-neutral beam injections. The equivalent fusion gain in DT plasma achieved 0.11 in a negative-ion-based neutral beam heated plasma. Time evolution of Sn following the short pulse neutral beam injection into the electron–cyclotron-heated low-beta plasma is reproduced by drift kinetic simulation, indicating that transport of a beam ion injected by a short pulse neutral beam can be described with neoclassical models in magnetohydrodynamic quiescent low-beta plasmas. The vertical neutron camera works successfully, demonstrating that in the co-neutral beam-injected plasma, the neutron emission profile shifts according to the magnetic axis position. The shift of the neutron emission profile is reproduced by orbit-following models. The triton burnup study is performed for the first time in a stellarator/heliotron to understand the alpha particle confinement. It is found that the triton burnup ratio, which largely increases at inward-shifted configurations due to the better triton orbit and better plasma performance in the inward-shifted configuration, is similar to that measured in a tokamak having a similar minor radius to the LHD. We study the confinement capability of EPs toward a helical reactor in the magnetohydrodynamic quiescent region and expansion of the energetic ion physics study in toroidal fusion plasmas.
高能粒子（EP）约束的理解是实现聚变反应堆的关键问题之一。在仿星器/螺旋装置中，EP约束研究是利用三维磁场灵活性获得更好约束的关键课题之一。在大型螺旋装置（LHD）中，已通过氢等离子体运行中的逃逸EP诊断进行了EP输运研究。随着LHD开始氘等离子体运行，利用新开发的综合中子诊断技术（提供芯部约束EP信息），EP约束研究取得了显著进展。由于磁轴内移时束离子轨道与磁面的偏离相对较小，总中子发射率（Sn）增加。Sn在电子密度约为2×10¹⁹ m⁻³至3×10¹⁹ m⁻³时出现峰值，与预测一致。研究发现，在同时进行同向和反向中性束注入的等离子体中，通过Fokker–Planck模型TASK/FP评估，束–束分量的比例约为20%。在负离子源中性束加热等离子体中，等效聚变增益达到了0.11。在电子回旋加热的低β等离子体中，短脉冲中性束注入后的Sn时间演化可通过漂移动力学模拟重现，这表明在磁流体动力学静止的低β等离子体中，短脉冲中性束注入的束离子输运可以用新经典模型描述。垂直中子相机工作正常，证明在同向中性束注入等离子体中，中子发射剖面随磁轴位置移动。该中子发射剖面的移动可通过轨道跟随模型重现。为理解α粒子约束，首次在仿星器/螺旋装置中进行了氚燃烧研究。研究发现，在内移位形下，由于氚离子轨道更好且等离子体性能更优，氚燃烧比显著增加，其数值与具有类似小半径的托卡马克中测得的结果相近。我们研究了在磁流体动力学静止区域中，面向螺旋反应堆的EP约束能力，以及环形聚变等离子体中高能离子物理研究的扩展。