Transmission of low-energy negative ions through insulating nanocapillaries

Zhang, Qi; Liu, Zhonglin; Li, Pengfei; Jin, Bo; Guang-Yin, Song; Jin, Duo; Niu, Ben; Wei, Long; Ha, Shuai; Xie, Yi-Ming; Ma, Yue; Wan, Rundong; Chen, Ying; Zhou, Peng; Zhang, Hongqiang; Chen, Ximeng

doi:10.1103/physreva.97.042704

Cited by 4 publications

(1 citation statement)

References 44 publications

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“…绝缘微管造价低廉、体积小, 并且带电粒子在其中通过自组织调节的充电过程传输而不需要额外的供能设备. 因此, 除正离子外, 负离子 [17][18][19][20] 、电子 [21][22][23][24][25][26][27][28][29][30][31][32] 、正电子 [33,34] 、μ子 [35,36] 等各种不同性质的带电粒子在绝缘微管中输运机制的研究也被广泛开展.…”

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Production and measurement of MeV proton microbeams in atmospheric environment based on glass capillary

Wan,

Pan,

Zhu

et al. 2024

Acta Phys. Sin.

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The production of the ion microbeam is traditionally by focusing or/and collimating to reduce the size of the beam to submicron meter scale. The traditional setup for the production of the microbeam consists of an expensive focusing and collimating system with a large space, based on electromagnetic fields. Meanwhile, the microbeam obtained through pure collimation by metal micro-tubes is limited by the fabrication processing, i.e., the beam spot size is very much limited by it in the scale of several microns and it is fabricated not as simple as that of a glass capillary. The use of inexpensive and easy-to-make glass capillaries as the tool for ion external microbeam production has become a new direction, inspired by early research on guiding effects. In this work, we used a glass capillary with the open outlet (108 μm in diameter), serving as a vacuum differential and collimating component, to produce a 2.5 MeV-proton microbeam directly into the atmosphere from the linear accelerator for the measurements. We measured the beam spot diameter and energy distribution of the microbeam as a function of the tilt angle of the capillary. We also conducted calculations and ion trajectory analysis on the scattering process of 2.5 MeV protons on the inner walls. The measurement results show that when the tilt angle is around 0°, there are a direct transmission part maintaining the initial incident energy, and a scattering part with the energy loss in the microbeam. It is found that the proportion of the directly transmitted protons and the beam spot size are at maximum around the tilt angle of zero. As the tilt angle increases, the beam spot diameter decreases; when the tilt angle is greater than the geometric angle, all the microbeam are from the scattering with the energy loss. The simulation combined with the ion trajectory analysis based on the scattering process explained the experimental results. It is found that the large angle scattering determines the overall external microbeam spot, while the central region of the beam spot is composed of directly penetrating ions, and its size is determined by the geometry of the glass capillary, i.e., the outlet diameter and the aspect ratio. The easy and inexpensive production of the external microbeam by glass capillaries has the nature benefits for its relative safe and stable operation, and the last but not least point is the simple positioning of the microbeam to the sample without the complex diagnostic tools. It is expected to be widely used in radiation biology, medicine, materials and other fields.

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Production and measurement of MeV proton microbeams in atmospheric environment based on glass capillary

Wan,

Pan,

Zhu

et al. 2024

Acta Phys. Sin.

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Experiments of keV negative ions transmitted through straight and tapered glass capillaries: tilt angle dependence

Song

Yang

et al. 2020

Eur. Phys. J. D

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Transmission of low-energy Cl– ions through Al2O3 insulating nanocapillaries

Ha¹,

Zhang²,

Xie³

et al. 2020

Acta Phys. Sin.

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<sec> The transmission of 10-keV Cl– ions through Al2O3 insulating nanocapillaries is studied both by experiment and simulation. The double-peak structure in the transmitted angular distribution is found to be the same as our previous result. The peak around the direction of the primary beam is caused mainly by the directly transmitted Cl–, and the other peak around the tilt angle of Al2O3 nanocapillaries is mainly induced by Cl+ and Cl0. The intensity of transmitted Cl– decreases with the tilt angle increasing, which is in accord with the geometrically allowed transmission. Beyond the geometrically allowed angle, the transmitted projectiles are mainly Cl+ ions and Cl0 atoms. The ratio of transmitted Cl+ ion to Cl0 atom drops as tilt angle increases, and it turns more obvious when the tilt angle is larger than the limit of the geometrical transmission.</sec><sec> A detailed physics process was developed within Geometry and Tracking 4 (Geant4) to perform the trajectory simulation, in which the forces from the deposited charges and the image charges, the scattering from the surfaces as well as the charge exchange are taken into consideration. The transmissions at the tilt angle of 1.6o are simulated for the cases without and with deposited charges of –100 e/capillary. For the deposition charge quantity of –100 e/capillary, the majority of the transmitted projectiles are mainly the directly transmitted Cl– ions exiting to the direction of tilt angle, and the transmitted Cl0 and Cl+ account for a very small portion. While for the case with no deposited charges, the simulation results agree well with the experimental results. The dependence of the scattering process on the tilt angle, which results in the different features in the transmitted projectiles, is studied in detail by the simulation. It is found that the transmitted Cl0 atoms exit through single to multiple scattering, and most of transmitted Cl0 atoms exit through single and double scattering, and are centered along the axis of nanocapillaries, while Cl+ ions mainly exit by single scattering, which results in the fact that the intensity of the transmitted Cl0 atoms drops slower than that of the transmitted Cl+ ions with the increase of the tilt angle, leading the ratio of the transmitted Cl+ to Cl0 to decrease as the tilt angle increases in experiment. </sec> <sec> Our results describe the physical mechanism of low-energy ions through insulating nanocapillaries in detail, i.e. how the scattering process dominates the final transmission. It is found that the transmission of the negative ions in the energy range above 10 keV is caused by the scattering and the charge exchange process.</sec>

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Transmission of low-energy negative ions through insulating nanocapillaries

Cited by 4 publications

References 44 publications

Production and measurement of MeV proton microbeams in atmospheric environment based on glass capillary

Production and measurement of MeV proton microbeams in atmospheric environment based on glass capillary

Experiments of keV negative ions transmitted through straight and tapered glass capillaries: tilt angle dependence

Transmission of low-energy Cl<sup>–</sup> ions through Al<sub>2</sub>O<sub>3</sub> insulating nanocapillaries

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