Purity of nitrogen ion beams produced in a plasma focus
Purity of nitrogen ion beams produced in a plasma focus
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等离子体焦点产生的氮离子束的纯度
DOI：
10.1088/0963-0252/12/3/315
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发表时间：
2003
影响因子：
3.8
通讯作者：
K. Masugata
中科院分区：
文献类型：
--
作者：
K. Takao;T. Honda;I. Kitamura;K. Masugata
为了提高等离子体聚焦（PF）中产生的离子束的纯度，研究了阳极形状对氮离子束特性的影响。使用两种类型的阳极，即杆型（A型）和中空型（B型），其中PF预填充有氮气。Thomson抛物线光谱仪测量结果表明，A型中存在大量的杂质离子O 1 -2+、C+、Cu 1 -2+和氮离子（N1-3+），且氮离子的百分比仅为25%。相反，在类型B中，杂质大大减少，氮离子的百分比提高到91%。氮束的最大能量和功率亮度在A型中被评估为0.5 MeV和0.23 GW cm−2 sr，在B型中被评估为1 MeV和1.6 GW cm−2 sr;因此，在B型中能量和亮度也被增强。从X射线针孔图像可以看出，A型阳极顶部有较强的电子辐照，而B型阳极的电子辐照较弱，且辐照区域远离箍缩等离子体。因此，认为A型中观察到的杂质离子是在以下过程中产生的。由于电子在阳极顶部的强烈照射，电极和电极上的吸收气体被蒸发，与箍缩等离子体混合并被氮离子加速。
To improve the purity of ion beams produced in a plasma focus (PF), the dependence of the characteristics of the nitrogen ion beams on the shape of the anode was investigated. Two types of anodes, i.e. rod type (type A) and hollow type (type B) were used with a PF pre-filled with nitrogen gas. Thomson parabola spectrometer measurements showed the existence of a large amount of impurity ions, O1–2+, C+, and Cu1–2+, with nitrogen ions (N1–3+) and the percentage of nitrogen ions is only 25% in type A. In contrast, in type B the impurity is extremely reduced and the percentage of nitrogen ions is enhanced to 91%. The maximum energies and power brightnesses of the nitrogen beams were evaluated to be 0.5 MeV and 0.23 GW cm−2 sr in type A and 1 MeV and 1.6 GW cm−2 sr in type B; hence, energy and brightness are also enhanced in type B. From x-ray pinhole images we see that strong electron irradiation occurs on the top of the anode in type A, whereas in type B, electron irradiation is weak and irradiation area is far from the pinch plasma. Hence, the impurity ions observed in type A are considered to be produced in the following process. Due to the strong irradiation of electrons on the anode top, the electrode and the absorbed gas on the electrode are vaporized, mixed with pinch plasma and accelerated with nitrogen ions.