A secondary electron yield test device for vacuum material study is set up,and its detailed design described in this paper.The test results for a few common vacuum materials with and without TiN film coating are prese...A secondary electron yield test device for vacuum material study is set up,and its detailed design described in this paper.The test results for a few common vacuum materials with and without TiN film coating are presented,and the influential factors on secondary electron yield are analyzed.All the work will be helpful to the surface pretreatment of vacuum materials.展开更多
Since the position of the electron in a hydrogen atom cannot be determined, the region in which it resides is said to be determined stochastically and forms an electron cloud. The probability density function of the s...Since the position of the electron in a hydrogen atom cannot be determined, the region in which it resides is said to be determined stochastically and forms an electron cloud. The probability density function of the single electron in 1s orbit is expressed as φ2, a function of distance from the nucleus. However, the probability of existence of the electron is expressed as a radial distribution function at an arbitrary distance from the nucleus, so it is estimated as the probability of the entire spherical shape of that radius. In this study, it has been found that the electron existence probability approximates the radial distribution function by assuming that the probability of existence of the electron being in the vicinity of the nucleus follows a normal distribution for arbitrary x-, y-, and z-axis directions. This implies that the probability of existence of the electron, which has been known only from the distance information, would follow a normal distribution independently in the three directions. When the electrons’ motion is extremely restricted in a certain direction by the magnetic field of both tokamak and helical fusion reactors, the probability of existence of the electron increases with proximity to the nucleus, and as a result, it is less likely to be liberated from the nucleus. Therefore, more and more energy is required to free the nucleus from the electron in order to generate plasma.展开更多
Electron cloud interaction with high energy positive beams are believed responsible for various undesirable effects such as vacuum degradation, collective beam instability and even beam loss in high power proton circu...Electron cloud interaction with high energy positive beams are believed responsible for various undesirable effects such as vacuum degradation, collective beam instability and even beam loss in high power proton circular accelerators. An important uncertainty in predicting electron cloud instability lies in the detailed processes of the generation and accumulation of the electron cloud. The simulation on the build-up of electron cloud is necessary to further studies on beam instability caused by electron clouds. The China Spallation Neutron Source （CSNS） is an intense proton accelerator facility now being built, whose accelerator complex includes two main parts： an H-linac and a rapid cycling synchrotron （RCS）. The RCS accumulates the 80 MeV proton beam and accelerates it to 1.6 GeV with a repetition rate of 25 Hz. During beam injection with lower energy, the emerging electron cloud may cause serious instability and beam loss on the vacuum pipe. A simulation code has been developed to simulate the build-up, distribution and density of electron cloud in CSNS/RCS.展开更多
The radial wave functions of inner electron shell and outer electron shell of a Ne atom were obtained by the approximate analytical method and tested by calculating the ground state energy of the Ne atom. The equivale...The radial wave functions of inner electron shell and outer electron shell of a Ne atom were obtained by the approximate analytical method and tested by calculating the ground state energy of the Ne atom. The equivalent volume of electron cloud and the refractive index of Ne were calculated. The calculated refractive index agrees well with the experimental result. Relationship between the refractive index and the wave function of Ne was discovered.展开更多
The perovskite transition metal oxide(TMO) has been considered in electrocatalysis for the modern clean energy technologies as its high electrochemical activity and low cost. The atomic scale engineering to the local ...The perovskite transition metal oxide(TMO) has been considered in electrocatalysis for the modern clean energy technologies as its high electrochemical activity and low cost. The atomic scale engineering to the local stoichiometry of single crystal TMO provides a clue of the relation between electronic structure and catalytic performance. Here we report a hydrogen evolution reaction(HER) activity enhancement ~ 1761% of Bi_(0.85)Sr_(0.15)FeO_3 compared to the pure BiFeO_3. By the systemic investigation of the Sr doping level of Bi_(1-x)Sr_xFeO_3(BSFO), it is found that the HER enhancement originates from the improvement of ferromagnetism of BSFO without obvious scarification of the ferroelectricity at the room temperature. The multiple ferroic orderings in BSFO are beneficial for HER activity, which offers the strengthen of hybridization of Fe 3d and O2 p orbitals from the view of ferromagnetism, and the assistance of electron drift by spontaneous electric polarization. Our study not only affords the strategy of developing multiple ferroic orderings in TMO, but also facilitates the atomic scale understanding of the improved HER activity.展开更多
文摘A secondary electron yield test device for vacuum material study is set up,and its detailed design described in this paper.The test results for a few common vacuum materials with and without TiN film coating are presented,and the influential factors on secondary electron yield are analyzed.All the work will be helpful to the surface pretreatment of vacuum materials.
文摘Since the position of the electron in a hydrogen atom cannot be determined, the region in which it resides is said to be determined stochastically and forms an electron cloud. The probability density function of the single electron in 1s orbit is expressed as φ2, a function of distance from the nucleus. However, the probability of existence of the electron is expressed as a radial distribution function at an arbitrary distance from the nucleus, so it is estimated as the probability of the entire spherical shape of that radius. In this study, it has been found that the electron existence probability approximates the radial distribution function by assuming that the probability of existence of the electron being in the vicinity of the nucleus follows a normal distribution for arbitrary x-, y-, and z-axis directions. This implies that the probability of existence of the electron, which has been known only from the distance information, would follow a normal distribution independently in the three directions. When the electrons’ motion is extremely restricted in a certain direction by the magnetic field of both tokamak and helical fusion reactors, the probability of existence of the electron increases with proximity to the nucleus, and as a result, it is less likely to be liberated from the nucleus. Therefore, more and more energy is required to free the nucleus from the electron in order to generate plasma.
基金Supported by National Natural Science Foundation of China(11275221,11175193)
文摘Electron cloud interaction with high energy positive beams are believed responsible for various undesirable effects such as vacuum degradation, collective beam instability and even beam loss in high power proton circular accelerators. An important uncertainty in predicting electron cloud instability lies in the detailed processes of the generation and accumulation of the electron cloud. The simulation on the build-up of electron cloud is necessary to further studies on beam instability caused by electron clouds. The China Spallation Neutron Source （CSNS） is an intense proton accelerator facility now being built, whose accelerator complex includes two main parts： an H-linac and a rapid cycling synchrotron （RCS）. The RCS accumulates the 80 MeV proton beam and accelerates it to 1.6 GeV with a repetition rate of 25 Hz. During beam injection with lower energy, the emerging electron cloud may cause serious instability and beam loss on the vacuum pipe. A simulation code has been developed to simulate the build-up, distribution and density of electron cloud in CSNS/RCS.
基金Supported by the New Star Program of Beijing Science and Technology, China (Grant No. 952870400)the Beijing Municipal Commission of Education,and the Excellent Young Teachers Program of Ministry of Education, China
文摘The radial wave functions of inner electron shell and outer electron shell of a Ne atom were obtained by the approximate analytical method and tested by calculating the ground state energy of the Ne atom. The equivalent volume of electron cloud and the refractive index of Ne were calculated. The calculated refractive index agrees well with the experimental result. Relationship between the refractive index and the wave function of Ne was discovered.
基金supported by the National Natural Science Foundation of China (Nos. 51772126 and 21978110)the Jilin Province Science and Technology Department Program (Nos. 20200201277JC, 20200201279JC, 20190201309JC and 20190101009JH)+4 种基金the National Science Foundation of Heilongjiang Province (E2017031)the Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education (Nos. 2017002, 2016010, 2015003 and 2015011)the Jilin Province Development and Reform Commission Program (Nos. 2019C042-1 and 2020C026-3)the ‘‘13th five-year” science and technology project of Jilin provincial education department (No. JJKH20200407KJ)the Jilin Province Fund for Talent Development Program (No. [2019] 874)。
文摘The perovskite transition metal oxide(TMO) has been considered in electrocatalysis for the modern clean energy technologies as its high electrochemical activity and low cost. The atomic scale engineering to the local stoichiometry of single crystal TMO provides a clue of the relation between electronic structure and catalytic performance. Here we report a hydrogen evolution reaction(HER) activity enhancement ~ 1761% of Bi_(0.85)Sr_(0.15)FeO_3 compared to the pure BiFeO_3. By the systemic investigation of the Sr doping level of Bi_(1-x)Sr_xFeO_3(BSFO), it is found that the HER enhancement originates from the improvement of ferromagnetism of BSFO without obvious scarification of the ferroelectricity at the room temperature. The multiple ferroic orderings in BSFO are beneficial for HER activity, which offers the strengthen of hybridization of Fe 3d and O2 p orbitals from the view of ferromagnetism, and the assistance of electron drift by spontaneous electric polarization. Our study not only affords the strategy of developing multiple ferroic orderings in TMO, but also facilitates the atomic scale understanding of the improved HER activity.
