Design and experimental study of magnetic field regulating ion source
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摘要: 磁场调控型离子源在离子源等离子体扩散空间中引入轴向强脉冲磁场，磁场起两方面的作用，一是形成潘宁放电效应，使原子、气体分子碰撞电离效率增加；二是在脉冲强磁场的作用下，强轴向磁场将质量较轻的离子约束在轴线上，对质量较重的金属离子约束能力较弱，导致其在等离子体膨胀引出通道中碰壁损失，能够提升引出轻离子的比例。开展了磁场调控的离子源放电结构、强脉冲螺线管磁场以及引出束流光学结构的设计；测量分析了引出离子流强和离子打靶束斑形貌。研究结果表明，强轴向磁场通过等离子体对混合离子成分的筛选作用，可有效提高引出离子流强中的轻离子成分比例。Abstract: A magnetic field regulating ion source introduces strong pulsed magnetic field in the discharge plasma region of the ion source. On one hand, it forms Penning discharge effect to enhance the collision ionization efficiency of the atoms and gas molecules due to the magnetic field. On the other hand, the light ions are restrained along the axis by the strong magnetic field, but it can’t restrain the heavy metal ions. This phenomenon results in the heavy ions loss by colliding wall of the plasma expansion extraction channel, so it promotes the ratio of the light ions. Discharge structure of a magnetic field regulating ion source and strong pulsed solenoid magnetic field, as well as the optic structure of extraction beam are designed and depicted in this paper. Intensity of extraction ion beam and beam spot on the target measured by scintillator screen are analyzed in this paper. The results show that the strong axial magnetic field increases the proportion of light ion components as the result of filtering effect for plasma with mixed ion component.
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Key words:
- magnetic field regulating /
- ion source /
- ion isolation /
- ion extraction /
- beam spot measurement /
- neutron yield
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图 1 轻、重离子在螺线管轴向磁场中的运动轨迹
Figure 1. Trajectory of light and heavy ions in the axial magnetic field of solenoid
图 4 磁场调控型离子源结构及仿真设计
Figure 4. Structure and simulation design of magnetic field regulating ion source
图 6 弧流52 A时不同放电状态下束斑形貌
Figure 6. Beam profile of different discharge status at 52 A arc current
表 1 磁场调控型离子源引出离子流
Table 1. Extracting ion current of magnetic field regulating ion source
extracting voltage/kV arc current/A target current/mA accelerating electrode current/A 110 66 280 0.1 110 102 310 1.0 110 150 360 10.0 
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