The electron impact excitation(EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the p...The electron impact excitation(EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the present work, an effective method to calculate the EIE cross sections of an atom/ion in the whole energy region is presented. We use the EIE cross sections of helium as an illustration example. The optical forbidden 1^(1)S–n^(1)S(n = 2–4) and optical allowed 1^(1)S–n^(1)P(n = 2–4) excitation cross sections are calculated in the whole energy region using the scheme that combines the partial wave R-matrix method and the first Born approximation. The calculated cross sections are in good agreement with the available experimental measurements. Based on these accurate cross sections of our calculation, we find that the ratios between the accurate cross sections and Born cross sections are nearly the same for different excitation final states in the same channel. According to this interesting property, a universal correction function is proposed and given to calculate the accurate EIE cross sections with the same computational efforts of the widely used Born cross sections,which should be very useful in the related application fields. The datasets presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00142.展开更多
Fully differential cross-sections of single ionization of He and Ne atoms are studied by linearly polarized extreme ultraviolet(XUV)photons in the energy range of 22.1 e V–43.7 e V,using a reaction microscope.Photoel...Fully differential cross-sections of single ionization of He and Ne atoms are studied by linearly polarized extreme ultraviolet(XUV)photons in the energy range of 22.1 e V–43.7 e V,using a reaction microscope.Photoelectron angular distributions and theβasymmetry parameters for He 1s^(2) electrons prove the reliability of our experiment,and the β asymmetry parameters extracted from the angular distributions of Ne 2p^(6) electrons are obtained.By comparing with different theoretical calculations,it is found that the contribution of the electron correlation effect in Ne 2p^(6) single ionization becomes increasingly important as the incident photon energy increases,while the relativistic effect is relatively low in the whole incident energy range.Our experimentalβasymmetry parameters may serve as a significant reference to test the most elaborated theories in the field.The datasets presented in this paper,including the photoelectron angular distributions andβasymmetry parameters,are openly available at https://doi.org/10.57760/sciencedb.j00113.00073.展开更多
Fishbone instability excited by barely trapped suprathermal electrons （BTSEs） in tokamaks is investigated theoretically. The frequency of the mode is found to close to procession frequency of BTSEs. The growth rate ...Fishbone instability excited by barely trapped suprathermal electrons （BTSEs） in tokamaks is investigated theoretically. The frequency of the mode is found to close to procession frequency of BTSEs. The growth rate of the mode is much smaller than that of the ideal magnetohytrodynamic （MHD） internal kink mode that is in contrast to the case of trapped ion driven fishbone instability. The analyses also show that spatial density gradient reversal is necessary for the instability. The correlation of the results with experiments is discussed.展开更多
介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEG...介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEGS光束线站在2021年12月通过工艺验收,2022年10月进入到试运行阶段,2023年9月对用户开放运行。SLEGS是国际上首台采用变换碰撞角度连续改变伽马束能量的光束线站,具有最好的能量扫描精度、流强密度以及高效的能量调节能力。试运行阶段SLEGS光束线站重点解决了伽马束能谱和流强的在线监测问题,主要完成了平坦效率谱仪(FED)测量光中子截面的实验方法学研究,以及开展了伽马成像、伽马活化、正电子产生等应用平台的拓展和研究。随着逆康普顿散射技术的发展和应用需求的增加,未来短脉冲、高极化、高通量以及小型化的激光康普顿散射光源将会迎来更好的发展机遇,将在核物理、天体物理、粒子物理、极化物理,以及航空航天、医学检测、能源开发等伽马源应用研究领域发挥重要的作用。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 12241410)。
文摘The electron impact excitation(EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the present work, an effective method to calculate the EIE cross sections of an atom/ion in the whole energy region is presented. We use the EIE cross sections of helium as an illustration example. The optical forbidden 1^(1)S–n^(1)S(n = 2–4) and optical allowed 1^(1)S–n^(1)P(n = 2–4) excitation cross sections are calculated in the whole energy region using the scheme that combines the partial wave R-matrix method and the first Born approximation. The calculated cross sections are in good agreement with the available experimental measurements. Based on these accurate cross sections of our calculation, we find that the ratios between the accurate cross sections and Born cross sections are nearly the same for different excitation final states in the same channel. According to this interesting property, a universal correction function is proposed and given to calculate the accurate EIE cross sections with the same computational efforts of the widely used Born cross sections,which should be very useful in the related application fields. The datasets presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00142.
基金the National Natural Science Foundation of China(Grant Nos.11905089 and U1932133)the National Key Research and Development Program of China(Grant No.2017YFA0402300)。
文摘Fully differential cross-sections of single ionization of He and Ne atoms are studied by linearly polarized extreme ultraviolet(XUV)photons in the energy range of 22.1 e V–43.7 e V,using a reaction microscope.Photoelectron angular distributions and theβasymmetry parameters for He 1s^(2) electrons prove the reliability of our experiment,and the β asymmetry parameters extracted from the angular distributions of Ne 2p^(6) electrons are obtained.By comparing with different theoretical calculations,it is found that the contribution of the electron correlation effect in Ne 2p^(6) single ionization becomes increasingly important as the incident photon energy increases,while the relativistic effect is relatively low in the whole incident energy range.Our experimentalβasymmetry parameters may serve as a significant reference to test the most elaborated theories in the field.The datasets presented in this paper,including the photoelectron angular distributions andβasymmetry parameters,are openly available at https://doi.org/10.57760/sciencedb.j00113.00073.
基金Supported by National Natural Science Foundations of China under Grant Nos. 19885006, 10175020 and 10135020.
文摘Fishbone instability excited by barely trapped suprathermal electrons （BTSEs） in tokamaks is investigated theoretically. The frequency of the mode is found to close to procession frequency of BTSEs. The growth rate of the mode is much smaller than that of the ideal magnetohytrodynamic （MHD） internal kink mode that is in contrast to the case of trapped ion driven fishbone instability. The analyses also show that spatial density gradient reversal is necessary for the instability. The correlation of the results with experiments is discussed.
文摘介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEGS光束线站在2021年12月通过工艺验收,2022年10月进入到试运行阶段,2023年9月对用户开放运行。SLEGS是国际上首台采用变换碰撞角度连续改变伽马束能量的光束线站,具有最好的能量扫描精度、流强密度以及高效的能量调节能力。试运行阶段SLEGS光束线站重点解决了伽马束能谱和流强的在线监测问题,主要完成了平坦效率谱仪(FED)测量光中子截面的实验方法学研究,以及开展了伽马成像、伽马活化、正电子产生等应用平台的拓展和研究。随着逆康普顿散射技术的发展和应用需求的增加,未来短脉冲、高极化、高通量以及小型化的激光康普顿散射光源将会迎来更好的发展机遇,将在核物理、天体物理、粒子物理、极化物理,以及航空航天、医学检测、能源开发等伽马源应用研究领域发挥重要的作用。
