Characterisation of negative ion beam focusing based on phase space structure
Characterisation of negative ion beam focusing based on phase space structure
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DOI：
10.1088/1367-2630/ab6d41
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发表时间：
2020-02
影响因子：
3.3
通讯作者：
Y. Haba;K. Nagaoka;K. Tsumori;M. Kisaki;H. Nakano;K. Ikeda;M. Osakabe
中科院分区：
文献类型：
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作者：
Y. Haba;K. Nagaoka;K. Tsumori;M. Kisaki;H. Nakano;K. Ikeda;M. Osakabe
负离子束聚焦是负离子束高级应用的关键要素，例如粒子物理加速器、医学领域的紧凑型加速器以及核聚变等离子体实验，因为等离子体源和栅极系统内部都存在复杂的磁场。为了了解束流聚焦，使用国家融合科学研究所研发的负离子源对单个子束进行了相空间结构测量。在等离子栅附近平行于滤波器磁场的方向上观察到复杂的相空间结构，而在垂直于滤波器场的方向上观察到单高斯子束结构。对单束束相空间结构的详细分析表明，复杂的结构可以被识别为具有不同束轴的三个光束分量的组合。还观察到每个轴的偏移取决于加速电压与提取电压的比率，这可能显着降低子束聚焦。
Negative ion beam focusing is a key element for advanced applications of negative ion beams such as accelerators for particle physics, compact accelerators for medical fields, and plasma experiments for nuclear fusion because complicated magnetic fields exist both inside of the source plasma and the grid system. In order to understand the beam focusing, phase space structure measurements for a single beamlet have been performed with a research-and-development negative ion source at the National Institute for Fusion Science. A complicated phase space structure is observed in the direction parallel to the filter magnetic field in the vicinity of the plasma grid, while a single-Gaussian beamlet structure is observed in the direction perpendicular to the filter field. Detailed analyses for the phase space structure of the single beamlet reveal that the complicated structure can be identified as a combination of three beam components with different beam axes. The shifts of each axis are also observed to depend on the ratio of the acceleration voltage for the extraction voltage, which may significantly degrade the beamlet focusing.