Study on neutral particle behavior in non-axisymmetric minimum-B region of a tandem mirror

本研究的目的是测量锚盒和锚最小B区过渡区的氢巴耳末α（Hα）线发射。我们还使用蒙特-卡罗代码“DEGAS”进行了中性传输模拟。在这个模拟中，我们预测了非轴对称锚镜盒中氢原子和氢分子的密度和温度分布，从而获得了关于粒子在这种复杂磁结构中输运的重要知识。为了测量窄视场的线发射，要求探测器具有高的空间分辨率，采用标准光源研究了探测器的空间分辨率特性。首次将三维蒙特-卡罗中性粒子模拟程序“DEGAS ver.63”应用于伽马10锚室，并对该区域进行了模拟研究。 ...更多信息 开始了建立了初步的网格模型，并进行了三维仿真。从模拟结果可以看出，两种粒子源（镜喉气体吹气器和位于锚盒外过渡区的限制器）成功地解释了锚盒中Hα线发射的测量结果。在本财政年度，利用上述探测器阵列首次成功测量了锚盒外过渡区的Hα线发射的详细结构。结果表明，在椭圆形等离子体截面中，Hα谱线强度沿矿轴方向沿着有一个强峰。相反，在沿磁场线的轴向沿着方向上，线强度的空间分布变得平坦。为了解释所获得的结果，一个新的网格模型，覆盖从锚细胞的塞/屏障细胞，并进行详细的模拟，这些细胞的现实结构的基础上。考虑粒子源从限制器在这个区域的模拟结果显示出良好的协议与测量的配置文件。建立了从中心单元到锚单元的统一网格模型，有效地模拟了中心单元和锚单元之间的中性输运过程。结果表明，等离子体和真空室壁的三维结构对中性输运起着重要的作用。少

The objective of this research is to measure he Hydrogen Balmer-alpha(Hα) line emission from the anchor cell and from the transition region in the anchor minimum-B region. We also performed a neutral transport simulation using a Monte-Carlo code "DEGAS". In this simulation, the density and temperature profiles of hydrogen atoms and molecules are predicted in non-axismmetric anchor mirror cell and hence a important knowledge with particle transport in such complicated configuration of this magnetic structure.In the last fiscal year, a newly designed two-dimensional Hα detector array was constructed. In order to measure the line emission from the narrow viewing area, the detector was required to obtain a high spatial resolution and its characteristics of the detector were investigated by using a standard lamp. A three-dimensional Monte-Carlo neutral particle simulation code "DEGAS ver.63" was applied to the GAMMA 10 anchor cell for the first time and a simulation study in this region was … More started. A preliminary mesh model was constructed and three-dimensional simulation was carried out. From this simulation, it was found that two particle sources (mirror throat gas puffer and a limiter at the outer transition region of the anchor cell) successfully explain the measured results of Hα line-emission in the anchor cell.In this fiscal year, the first measurement of detailed structure of the Hα line-emission in the anchor outer-transition region was successfully performed using the above detector array. It was found that the measured Hα line intensity has a strong peak along the miner axis of elliptically elongated plasma cross-section. On the contrary, in an axial direction along the magnetic field line, the spatial profile of the line intensity became flat. In order to explain the obtained results, a new mesh model covering from the anchor cell to the plug/barrier cell was constructed and detailed simulation based on the realistic structure of these cells was performed. The simulation results considering a particle source from the limiter at this region showed a good agreement with the measured profiles. A unified mesh mode covering from the central-cell to the anchor-cell was successfully built up, which enabled to precisely simulate the neutral transport in the connecting region between the two cells efficiently. From the above results, the three-dimensional structure of plasma and vacuum chamber wall plays an important roll in neutral transport in this region. Less