Nonuniform plasma meniscus modelling based on backward calculation of negative ion beamlet
Nonuniform plasma meniscus modelling based on backward calculation of negative ion beamlet
复制标题
基于负离子子束逆向计算的非均匀等离子体弯月面建模
DOI：
10.1088/1741-4326/ac8604
复制
发表时间：
2022
期刊：
影响因子：
3.3
通讯作者：
M. Osakabe
中科院分区：
文献类型：
--
作者：
M. Kisaki;K. Nagaoka;J. Slief;Y. Haba;R. Nakamoto;K. Tsumori;H. Nakano;K. Ikeda;M. Osakabe
等离子体半月板的形状是决定光束聚焦的关键因素。氢负离子源半月板形成的物理模型尚未建立。为了得到半月板处的粒子信息，在实验观测的基础上进行了反向轨迹计算。观察到负离子密度在平行于抑制共萃取电子的磁体方向上具有空间不均匀性。在正向轨迹计算中，考虑了半月板附近负离子密度的不均匀性。结果表明，不均匀的负离子分布导致了光束在相空间聚焦的退化和光束分裂。讨论了负离子空间分布在半月板模型中的重要性，并与均匀提取模型进行了比较。
The shape of a plasma meniscus is a key factor to determine the beam focusing. The physics model of the meniscus formation for hydrogen negative ion sources has not been established yet. A backward trajectory calculation based on experimental observation is performed in order to derive the particle information at the meniscus. It is observed that the negative ion density is spatially nonuniform in the direction parallel to the magnets for suppression of co-extracted electrons. A nonuniformity of the negative ion density in the vicinity of the meniscus is taken into account in the forward trajectory calculation. It reveals that the nonuniform negative ion distribution leads to degradation of the beam focusing and the beam splitting in phase space. The importance of the spatial distribution of negative ions on meniscus modelling is discussed with a comparison to uniform extraction model.