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研制的多靶强流铯溅射离子源加工完成后,在中国原子能研究院的400 kV小型重核素加速器质谱(AMS)装置[16-17]上进行了测试,实物如图8所示。在
$ ^{12}{\rm{C}}^{-} $ 离子出束实验中,保持铯容器温度136 °C、电离器电流26.5 A、阴极电压5 kV、铯聚焦电压4.7 kV、引出电压16.2 kV、真空度6.8 × 10−5 Pa等条件不变,每间隔30 min通过上位机软件远程控制阴极靶盘旋转到不同的靶位后复位,3小时内测得同一靶位的石墨样品产生$ ^{12}{\rm{C}}^{-} $ 离子流强始终保持在31 µA左右,初步验证了阴极靶盘上靶位的可重复性及自动换靶装置定位的精准性,证明了离子源供束稳定、引出负离子流强较大。为了进一步地检验离子源的性能,在铯容器温度约为131 °C、电离器电流为26.5 A、引出电压为18.5 kV、真空状态维持在6.8 × 10−5 Pa的条件下,测试铯聚焦电压、阴极电压对
$ ^{12} {\rm{C}}^{-}$ 离子引出束流的影响,实验结果经数据统计和处理后如图9、图10所示。从图9中可看出:$ ^{12} {\rm{C}} ^{-} $ 离子束流随铯聚焦电压的升高先较快地增长,当铯聚焦电压达到1.4 kV之后,开始缓慢增加趋近于最大值,这表明离子源的对${\rm{Cs}} ^{+} $ 离子聚焦效果随铯聚焦电压的升高变好,最终几乎将电离的${\rm{ Cs}}^{+} $ 离子全都聚焦于靶物质上,初级溅射${\rm{Cs}} ^{+} $ 离子流强增加,从而提高$ ^{12}{\rm{C}} ^{-} $ 离子产额,增大$ ^{12}{\rm{C}} ^{-} $ 离子流强,直到趋近最大值。由4.1节中$ {\rm{Cs}}^{+} $ 离子流强计算(2)式可知,随阴极电压的升高,${\rm{Cs}} ^{+} $ 离子流强增加,当铯聚焦电压不变时,轰击在靶上有效的${\rm{ Cs}}^{+} $ 离子流强会逐渐增加至饱和值,故图10中引出的$ ^{12}{\rm{C}} ^{-} $ 离子束流随阴极电压的变化也是先增加后趋于平稳。$ ^{12}{\rm{C}}^{-} $ 离子束流测试结果表明,离子源的铯聚焦效果良好,产生的负离子束流流强及传输满足设计的要求。根据近两年在AMS装置上开展的科研工作,从相应的实验结果中得出了离子源产生某些样品负离子的流强数据(数据为实验值而非最大值),并与同等实验条件下NEC公司的多靶铯溅射负离子源的束流流强进行对比,各自实验数据列于表1。从表中可以看出,对于同一种类离子,研制的离子源与NEC离子源实验结果无明显差异,提供的负离子束都能很好地满足实验要求,基本达到了进口源的水平。
离子种类 样品材料 束流流强/μA 束流流强(NEC)/μA ${\rm{H}} ^{-} $ ${\rm{TiH}} _2 $ + Nb 20 24 $ ^{12}{\rm{C}}^{-} $ 石墨(C) 60 58 $ ^{32}{\rm{S}} ^{-} $ FeS +Ag 22 25 $ ^{35}{\rm{Cl}} ^{-} $ AgCl +Ag 30 31 $ ^{127}{\rm{I}}^{-} $ AgI +Ag 12 10
Development of a Multi-Sample High Intensity Cs Sputter Ion Source
doi: 10.11804/NuclPhysRev.39.2021055
- Received Date: 2021-07-17
- Rev Recd Date: 2021-09-03
- Publish Date: 2022-09-20
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Key words:
- multi-sample /
- sputter ion source /
- structural design /
- simulation analysis
Abstract: Multi-sample high intensity Cs sputter ion source is one of the common ion sources in various accelerators, and has been widely used in scientific research and industrial production. However, the commercial products of this kind of ion source are monopolized by several European and American countries, and currently no domestic manufacturer can produce it. In order to enhance the independent innovation capability in accelerator operation and development, a multi-sample high intensity Cs sputter ion source was specially developed. The ion source mainly consists of ion source cavity, target replacement device, cooling system and control cabinet. According to the functional requirements, the key components of ion source were designed. A new servo motor-driven target method was adopted to provide fine-tuning of target position and remote control mode. And the Opera-3D software was used to simulate beam trajectory and optimize structural parameters. After testing, the ion source has been successfully used in a 400 kV compact accelerator mass spectrometer(AMS) independently developed by the China Institute of Atomic Energy. The sample is accurately positioned, and the beam current is stable. Beam parameters are as good as those of imported ion source, so the expected goal has been achieved.
Citation: | Wei GUO, Kangning LI, Qubo YOU, Libo PENG, Botao XU, Ming HE, Yueming HU, Yiwen BAO, Pan HU, Bin SHAO. Development of a Multi-Sample High Intensity Cs Sputter Ion Source[J]. Nuclear Physics Review, 2022, 39(3): 311-316. doi: 10.11804/NuclPhysRev.39.2021055 |