| Enhancement of electron–ion recombination rates at low energy range in the heavy ion storage ring CSRm |
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| 引用本文： | Nadir Khan,黄忠魁,汶伟强,汪书兴,汪寒冰,马万路,朱小龙,赵冬梅,冒立军,李杰,马晓明,汤梅堂,殷达钰,杨维青,杨建成,原有进,朱林繁,马新文.Enhancement of electron–ion recombination rates at low energy range in the heavy ion storage ring CSRm[J].中国物理 B,2020(3):169-175. |
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| 作者姓名： | Nadir Khan 黄忠魁 汶伟强 汪书兴 汪寒冰 马万路 朱小龙 赵冬梅 冒立军 李杰 马晓明 汤梅堂 殷达钰 杨维青 杨建成 原有进 朱林繁 马新文 |
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| 基金项目： | Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0402300);the National Natural Science Foundation of China(Grant Nos.U1932207,11904371,and U1732133)。 |
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| 摘 要： | Recombination of Ar14+, Ar15+, Ca16+, and Ni19+ ions with electrons has been investigated at low energy range based on the merged-beam method at the main cooler storage ring CSRm in the Institute of Modern Physics, Lanzhou,China. For each ion, the absolute recombination rate coefficients have been measured with electron–ion collision energies from 0 meV to 1000 meV which include the radiative recombination(RR) and also dielectronic recombination(DR)processes. In order to interpret the measured results, RR cross sections were obtained from a modified version of the semiclassical Bethe and Salpeter formula for hydrogenic ions. DR cross sections were calculated by a relativistic configuration interaction method using the flexible atomic code(FAC) and AUTOSTRUCTURE code in this energy range. The calculated RR + DR rate coefficients show a good agreement with the measured value at the collision energy above 100 meV.However, large discrepancies have been found at low energy range especially below 10 meV, and the experimental results show a strong enhancement relative to the theoretical RR rate coefficients. For the electron–ion collision energy below 1 meV, it was found that the experimentally observed recombination rates are higher than the theoretically predicted and fitted rates by a factor of 1.5 to 3.9. The strong dependence of RR rate coefficient enhancement on the charge state of the ions has been found with the scaling rule of q3.0, reproducing the low-energy recombination enhancement effects found in other previous experiments.
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| 关 键 词： | storage ring ELECTRON COOLER highly charged ions radiative recombination ENHANCEMENT |
Enhancement of electron–ion recombination rates at low energy range in the heavy ion storage ring CSRm |
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| Nadir Khan,Zhong-Kui Huang,Wei-Qiang Wen,Shu-Xing Wang,Han-Bing Wang,Wan-Lu Ma,Xiao-Long Zhu,Dong-Mei Zhao,Li-Jun Mao,Jie Li,Xiao-Ming Ma,Mei-Tang Tang,Da-Yu Yin,Wei-Qing Yang,Jian-Cheng Yang,You-Jin Yuan,Lin-Fan Zhu,Xin-Wen Ma.Enhancement of electron–ion recombination rates at low energy range in the heavy ion storage ring CSRm[J].Chinese Physics B,2020(3):169-175. |
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| Authors: | Nadir Khan Zhong-Kui Huang Wei-Qiang Wen Shu-Xing Wang Han-Bing Wang Wan-Lu Ma Xiao-Long Zhu Dong-Mei Zhao Li-Jun Mao Jie Li Xiao-Ming Ma Mei-Tang Tang Da-Yu Yin Wei-Qing Yang Jian-Cheng Yang You-Jin Yuan Lin-Fan Zhu Xin-Wen Ma |
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| Affiliation: | Institute of Modern Physics;University of Chinese Academy of Sciences;Hefei National Laboratory for Physical Sciences at Micro-scale |
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| Abstract: | Recombination of Ar14+, Ar15+, Ca16+, and Ni19+ ions with electrons has been investigated at low energy range based on the merged-beam method at the main cooler storage ring CSRm in the Institute of Modern Physics, Lanzhou,China. For each ion, the absolute recombination rate coefficients have been measured with electron–ion collision energies from 0 meV to 1000 meV which include the radiative recombination（RR） and also dielectronic recombination（DR）processes. In order to interpret the measured results, RR cross sections were obtained from a modified version of the semiclassical Bethe and Salpeter formula for hydrogenic ions. DR cross sections were calculated by a relativistic configuration interaction method using the flexible atomic code（FAC） and AUTOSTRUCTURE code in this energy range. The calculated RR + DR rate coefficients show a good agreement with the measured value at the collision energy above 100 meV.However, large discrepancies have been found at low energy range especially below 10 meV, and the experimental results show a strong enhancement relative to the theoretical RR rate coefficients. For the electron–ion collision energy below 1 meV, it was found that the experimentally observed recombination rates are higher than the theoretically predicted and fitted rates by a factor of 1.5 to 3.9. The strong dependence of RR rate coefficient enhancement on the charge state of the ions has been found with the scaling rule of q3.0, reproducing the low-energy recombination enhancement effects found in other previous experiments. |
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| Keywords: | storage ring electron cooler highly charged ions radiative recombination enhancement |
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