In this work, energetic-ion confinement and loss due to energetic-ion driven magnetohydrodynamic modes are studied using comprehensive neutron diagnostics and orbit-following numerical simulations for the Large Helical Device (LHD). The neutron flux monitor is employed in order to obtain global confinement of energetic ions and two installed vertical neutron cameras (VNCs) viewing different poloidal cross-sections are utilized in order to measure the radial profile of energetic ions. A strong helically-trapped energetic-ion-driven resistive interchange mode (EIC) excited in relatively low-density plasma terminated high-temperature state in LHD. Changes in the neutron emission profile due to the EIC excitation are clearly visualized by the VNCs. The reduction in the neutron signal for the helical ripple valley increases with EIC amplitude, which reaches approximately 50%. In addition to the EIC experiment, orbit-following simulations using the DELTA5D code with EIC fluctuations were performed to assess the energetic-ion transport and loss. Two-dimensional temporal evolution results show that the neutron emissivity at the helical ripple decreases significantly due to the EIC. The rapid reduction in neutron emissivity shows that the helically-trapped beam ions immediately escape from the plasma. The reduction in the VNC signals for the helical ripple valley and the total neutron emission rate increase with increasing EIC amplitude, as observed in the experiment. Calculated line-integrated neutron emission results show that the profile measured by VNC1 has one peak, whereas the profile measured by VNC2 has two peaks, as observed in the experiment. Although the neutron emission profile for VNC2 has a relatively wide peak compared with the experimental results, the significant decrease in neutron signal corresponding to the helical ripple valley was successfully reproduced.

中文翻译：

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大型螺旋装置中由螺旋俘获的高能离子驱动的电阻交换模式引起的高能粒子传输和损失

在这项工作中，使用大型螺旋装置 (LHD) 的综合中子诊断和轨道跟踪数值模拟，研究了由高能离子驱动的磁流体动力学模式引起的高能离子限制和损失。中子通量监测器用于获得高能离子的全局限制，并利用两个安装的垂直中子相机 (VNC) 查看不同的极向横截面，以测量高能离子的径向剖面。在 LHD 中以相对低密度等离子体终止高温状态激发的强螺旋俘获高能离子驱动电阻交换模式 (EIC)。VNC 清楚地显示了由于 EIC 激发引起的中子发射剖面的变化。螺旋纹波谷中子信号的减少随着 EIC 幅度的增加而增加，达到约 50%。除了 EIC 实验外，还使用带有 EIC 波动的 DELTA5D 代码进行轨道跟踪模拟，以评估高能离子传输和损失。二维时间演化结果表明，由于 EIC，螺旋纹波处的中子发射率显着降低。中子发射率的迅速降低表明螺旋形俘获的束离子立即从等离子体中逸出。如实验中所观察到的，螺旋纹波谷的 VNC 信号和总中子发射率随着 EIC 幅度的增加而增加。计算的线积分中子发射结果表明，如实验中所观察到的，VNC1 测量的轮廓具有一个峰值，而 VNC2 测量的轮廓具有两个峰值。