Dielectronic recombination(DR)is one of the dominant electron-ion recombination mechanisms for most highly charged ions(HCIs)in cosmic plasmas,and thus,it determines the charge state distribution and ionization balanc...Dielectronic recombination(DR)is one of the dominant electron-ion recombination mechanisms for most highly charged ions(HCIs)in cosmic plasmas,and thus,it determines the charge state distribution and ionization balance therein.To reliably interpret spectra from cosmic sources and model the astrophysical plasmas,precise DR rate coefficients are required to build up an accurate understanding of the ionization balance of the sources.The main cooler storage ring(CSRm)and the experimental cooler storage ring(CSRe)at the Heavy-Ion Research Facility in Lanzhou(HIRFL)are both equipped with electron cooling devices,which provide an excellent experimental platform for electron-ion collision studies for HCIs.Here,the status of the DR experiments at the HIRFL-CSR is outlined,and the DR measurements with Na-like Kr25^(+)ions at the CSRm and CSRe are taken as examples.In addition,the plasma recombination rate coefficients for Ar12^(+),14^(+),Ca14^(+),16^(+),17^(+),Ni19^(+),and Kr25^(+)ions obtained at the HIRFL-CSR are provided.All the data presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00092.展开更多
Based on the multi-configuration Dirac-Fock method, this paper has made theoretical calculations for the dielectronic recombination cross-sections and the high-n dielectronic satellites to Kα resonance line in helium...Based on the multi-configuration Dirac-Fock method, this paper has made theoretical calculations for the dielectronic recombination cross-sections and the high-n dielectronic satellites to Kα resonance line in helium-like aluminium ions. It is found that high-n dielectronic satellites are seriously mixed with resonance line, which leads to a significant increase in both the apparent width and the intensity of Kα resonance line. They also induce a positional shift of Kα resonance line.展开更多
The KLL dielectronic recombination （DR） processes of ions from highly charged helium-like to oxygen-like krypton, iodine and barium ions are studied systematically in the relativistic distorted-wave approximation wi...The KLL dielectronic recombination （DR） processes of ions from highly charged helium-like to oxygen-like krypton, iodine and barium ions are studied systematically in the relativistic distorted-wave approximation with configuration interaction. The KLL DR resonant energies, the corresponding resonant strengths and the theoretical spectra for each highly charged ion species are obtained. The results accord well with other available values. The behaviour of KLL resonant strengths for He-like ions with atomic number Z is analysed.展开更多
The relativistic configuration interaction method is employed to calculate the dielectronic recombination（DR） cross sections of helium-like krypton via the 1s2lnl ＇（n = 2,3,...,15） resonances.Then,the resonant tr...The relativistic configuration interaction method is employed to calculate the dielectronic recombination（DR） cross sections of helium-like krypton via the 1s2lnl ＇（n = 2,3,...,15） resonances.Then,the resonant transfer excitation（RTE） processes of Kr 34＋ colliding with H,He,H 2,and CH x（x = 0-4） targets are investigated under the impulse approximation.The needed Compton profiles of targets are obtained from the Hartree-Fock wave functions.The RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the target.For H 2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l ＇ to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H 2.For CH x（x = 0-4） targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CH x,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the hydrogen.However,further comparison of the individual orbital contributions of C（2p,2s,1s） and CH 4（1t 2,2a 1,1a 1） to the RTE cross sections shows that the molecular effects induce differences of about 25.1%,19.9%,and 0.2% between 2p-1t 2,2s-2a 1,and 1s-1a 1 orbitals,respectively.展开更多
The electron–ion recombination for phosphorus-like^（112） Sn^（35＋）has been measured at the main cooler storage ring of the Heavy Ion Research Facility in Lanzhou, China, employing an electron–ion merged-beams te...The electron–ion recombination for phosphorus-like^（112） Sn^（35＋）has been measured at the main cooler storage ring of the Heavy Ion Research Facility in Lanzhou, China, employing an electron–ion merged-beams technique. The absolute total recombination rate coefficients for electron–ion collision energies from 0 e V–14 e V are presented. Theoretical calculations of recombination rate coefficients were performed using the Flexible Atomic Code to compare with the experimental results. The contributions of dielectronic recombination and trielectronic recombination on the experimental rate coefficients have been identified with the help of the theoretical calculation. The present results show that the trielectronic recombination has a substantial contribution to the measured electron–ion recombination spectrum of^（112）Sn^（35＋）. Although a reasonable agreement is found between the experimental and theoretical results the precise calculation of the electron–ion recombination rate coefficients for M-shell ions is still challengeable for the current theory.展开更多
Armed with four different steady-state collisional-radiative(CR) models,we investigated the effect of dielectronic recombination(DR) on the charge-state distribution in laser-produced silicon plasma. To assess this ef...Armed with four different steady-state collisional-radiative(CR) models,we investigated the effect of dielectronic recombination(DR) on the charge-state distribution in laser-produced silicon plasma. To assess this effect,we performed a series of temporally resolved spectra of highly charged Si ions in the extreme ultraviolet region.Ab initio calculations of the DR rate coefficients were done for Si^(6+)–Si^(4+) ions. We also analyzed the evolution of the collisional ionization, radiative recombination, three-body recombination, photo-ionization, and DR rate coefficients as a function of electron temperature. The electron temperature and electron density for different delay times were obtained by comparing the normalized experimental and simulated spectra. The ion fraction and average charge state from the four different CR models were also obtained. The results indicate that the DR process has a greater influence in the stage of plasma evolution that cannot be neglected in plasma diagnoses.展开更多
This paper analyses the effect of configuration complex on dielectronic recombination （DR） process in highly ionized plasmas （Xe^26＋, Dy^38＋, W^46＋） by using the multiconfiguration relativistic Hartree-Fock met...This paper analyses the effect of configuration complex on dielectronic recombination （DR） process in highly ionized plasmas （Xe^26＋, Dy^38＋, W^46＋） by using the multiconfiguration relativistic Hartree-Fock method. Resonant and nonresonant radiative stabilizing transitions and decays to autoionizing levels followed by radiative cascades are included. Collisional transitions following electron capture are neglected. The remarkable difference between the isoelectronic trend of the rate coefficients for DR through 3d^94l4l′ and through 3d^94l5l′ is emphasized. The trend of DR through 3d^94l4l′ shows irregularities at relatively low temperature due to the progressive closing of DR channels as atomic number Z increases.展开更多
Ab initio calculation of the total dielectronic recombination （DR） rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration inter...Ab initio calculation of the total dielectronic recombination （DR） rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration interaction. The contributions to the total DR rate coefficients are explicitly calculated from the complexes of Ni-like tantalum：3s^23p^63d3/2^33d5/2^6n′l′,3s^23p^53d^10n′l′,3s3p^63d^10n′l′,3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′ and 3s3p^63d^94ln′l′ with n′≤25, and 3s^23p^63d^85ln′l′ with n′≤9.The l′and n′ dependences of partial DR rate coefficients are investigated. The contributions from higher n^complexes are evaluated by a level-by-level extrapolation method. The total DR rate coefficients mainly come from the complex series 3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′and are fitted to an empirical formula with high accuracy. Comparison of the present results with those of other works shows that the previously published data underestimate significantly the DR rates of Co-like tantalum.展开更多
In this work, the KLL dielectronic recombination （DR） processes of highly charged He-like to O-like xenon ions are studied systematically by using a DR program, which is based on the multi-configuration Dirac-Fock ...In this work, the KLL dielectronic recombination （DR） processes of highly charged He-like to O-like xenon ions are studied systematically by using a DR program, which is based on the multi-configuration Dirac-Fock （MCDF） method. The KLL DR resonant energies and the corresponding resonant strengths are calculated, emphasizing especially the effect of the Breit interaction on the DR strengths. The theoretical KLL DR spectra are obtained and compared with the latest experimental results obtained in the Shanghai Electron Beam Ion Trap.展开更多
Accurate data for dielectronic recombination of tungsten ions are essential in the modeling of tungsten impurity transport and radiative power loss in International Thermonuclear Experimental Reactor （ITER）. Theoret...Accurate data for dielectronic recombination of tungsten ions are essential in the modeling of tungsten impurity transport and radiative power loss in International Thermonuclear Experimental Reactor （ITER）. Theoretical calculations have been made for dielectronic recombi- nation （DR） rate coefficients of Br-like tungsten ions using a flexible relativistic atomic code （FAC） from i eV to 50 keV. Level-by-level calculations are carried out for evaluating the contributions to DR through all the relevant Kr-like tungsten ions autoionizing inner-shell excited configuration complexes： （3s23p63d10）-14s24p5nlntl＇ （n = 4-5, n＇ = 4-100,l＇ = 0-8）, （4s24pS）-lnln＇l＇ （n = 4-6, n＇ = 4-100, l＇ = 0-12）. Comparison of the rate coefficients for 3s, 3p, 3d, 4s and 4p subshell excitations shows that the 4p subshell excitation dominates over the whole temperature region, 4s subshell excitation at low temperature and 3p, 3d subshell excitations at high temperature can not be neglected. In order to facilitate simple applications, the total DR rate coefficient, △n = 0,1 and 2 core excitations DR rate coefficients are fitted to an empirical formula.展开更多
Dielectronic recombination is an important process in high temperature plasmas. In the present work, the KLn （n=L, M, N and O） DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai elec...Dielectronic recombination is an important process in high temperature plasmas. In the present work, the KLn （n=L, M, N and O） DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai electron beam ion trap using a fast electron beam energy scanning method. The experiment uncertainty reaches about 6% with significant improvement of statistics. A relativistic configuration interaction calculation is also made. Theoretical results agree with the experiment results within 15% in most cases.展开更多
Dielectronic recombination (DR) is an important electron–ion recombination process. This process is generallyconsidered to occur in two steps,e??+Aq+![A(q??1)+]![A(q??1)+]+nhv ; (1) where in the first step a free ...Dielectronic recombination (DR) is an important electron–ion recombination process. This process is generallyconsidered to occur in two steps,e??+Aq+![A(q??1)+]![A(q??1)+]+nhv ; (1) where in the first step a free electron is captured simultaneously with the excitation of a bound electron. In the second step the doubly-excited ion is stabilized by emitting photons.展开更多
Young's double-slit interference is a clear manifestation of the wave character of light. The feasibility of an atomicversion of Young's double slit experiment for matter waves in ion-atom collisions was first...Young's double-slit interference is a clear manifestation of the wave character of light. The feasibility of an atomicversion of Young's double slit experiment for matter waves in ion-atom collisions was first discussed theoreticallyby Tuan and Gerjuoy in 1960[1]. They studied capture processes in collisions of protons with H2 and suggestedthat diffraction of the protons from the two atomic centers of the molecule could lead to interference effects. Suchinterference effects are more difficult to observe in ionization processes, since there the final state of the collisioninvolves at least three unbound particles. The experimental observation of this process is particularly challengingbecause the determination of the phase angle in such processes is not straightforward.展开更多
The main cooler storage ring (CSRm) equipped with an electron-cooler creates an ideal platform for dielectronicrecombination (DR) experiments. In order to fully understand our DR experimental setup and especially the ...The main cooler storage ring (CSRm) equipped with an electron-cooler creates an ideal platform for dielectronicrecombination (DR) experiments. In order to fully understand our DR experimental setup and especially the electronenergy detuning system, we have performed a DR calibration experiment using the Li-like argon ions at theCSRm. The Ar15+ has a simple electronic structure so the DR spectrum can be calculated with an ultra-highprecision and compared with the existing experimental data. The experiment was carried out at the relative energyfrom 0 to 32 eV that includes all DR resonances associated with 2s1=2 ! 2p1=2 and most of the 2s1=2 ! 2p3=2excitations.展开更多
The total recombination rate coefficients of lithium-like 36Ar15+ ions have been measured by employing the electron-ion merged-beams technique at the heavy ion storage ring CSRm at IMP[1]. Fig. 1 (a) shows the DR spec...The total recombination rate coefficients of lithium-like 36Ar15+ ions have been measured by employing the electron-ion merged-beams technique at the heavy ion storage ring CSRm at IMP[1]. Fig. 1 (a) shows the DR spectrum for electron energy from 0 to 35 eV in the center-of-mass (c.m.) frame involving all the DR resonances associated with 2s1=2!2p1=2 and 2s1=2!2p3=2 excitations.展开更多
The relativistic configuration interaction method is employed to calculate the dielectronic recombination(DR) cross sections of helium-like krypton via the 1s2lnl ’(n = 2,3,...,15) resonances.Then,the resonant transf...The relativistic configuration interaction method is employed to calculate the dielectronic recombination(DR) cross sections of helium-like krypton via the 1s2lnl ’(n = 2,3,...,15) resonances.Then,the resonant transfer excitation(RTE) processes of Kr 34+ colliding with H,He,H 2,and CH x(x = 0-4) targets are investigated under the impulse approximation.The needed Compton profiles of targets are obtained from the Hartree-Fock wave functions.The RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the target.For H 2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l ’ to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H 2.For CH x(x = 0-4) targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CH x,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the hydrogen.However,further comparison of the individual orbital contributions of C(2p,2s,1s) and CH 4(1t 2,2a 1,1a 1) to the RTE cross sections shows that the molecular effects induce differences of about 25.1%,19.9%,and 0.2% between 2p-1t 2,2s-2a 1,and 1s-1a 1 orbitals,respectively.展开更多
The knowledge of accurate ionization and recombination rates of heavy ions is crucial for the study of X-ray lasers and inertia confine fusion ( ICF).The dielectronic recombination rates of Cu-like Ta44+ (1s22s22p63s2...The knowledge of accurate ionization and recombination rates of heavy ions is crucial for the study of X-ray lasers and inertia confine fusion ( ICF).The dielectronic recombination rates of Cu-like Ta44+ (1s22s22p63s23p63d104s1) ion through the (3d1041n’1’n’=4,5) configurations are given.The remarkable difference between the isoelectronic trends of the rate coefficients for dielectronic recombination through 3d104141’ and 3d104151’ is emphasized.展开更多
The storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination （DR） experiments. In order to fulfill the requirement of DR measurements at the main Cooler Storage Ring, a detun...The storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination （DR） experiments. In order to fulfill the requirement of DR measurements at the main Cooler Storage Ring, a detuning system for the precision control of the relative energy between the ion beam and the electron beam has been installed on the electron cooler device. The test run using 7.0 MeV/u C6＋ beam was performed with recording the Schottky spectra and the ion beam currents. The influence of pulse heights and widths of the detuning voltage on the ion beam was analyzed. For the small pulse height, the experimental results from the Schottky spectra were in good agreement with the theoretical results. The frequency shift in the Schottky spectra was significantly reduced for the short pulse width. For the large pulse height, an oscillation phenomenon was observed and some effective ways to reduce the oscillation were pointed out. The detailed description of the phenomenon and the theoretical model based on the plasma oscillation was discussed in this paper. The overall results show that the new detuning system works properly, and could fulfill the requirements of future DR experiment.展开更多
Ab initio calculations of dielectronic recombination(DR)processes from the ground state 1s 2 of He-like argon ion through doubly excited states 1s2snl,1s2pnl(n=2 to 9)of Li-like argon ions are performed using the mult...Ab initio calculations of dielectronic recombination(DR)processes from the ground state 1s 2 of He-like argon ion through doubly excited states 1s2snl,1s2pnl(n=2 to 9)of Li-like argon ions are performed using the multi-configuration HatreeFock method with relativistic correction.The theoretical method and its corresponding computation will be outlined.For higher doubly excited states with n>9,the scaling law is used to extrapolate the Auger and radiative transition rates.The total and stateto-state cross sections with corresponding rate coefficients in the temperature from 102 eV to 106 eV are presented,as well as the DR strengths for all the separate resonances.Moreover,peculiarities of the DR from doubly excited 1s2s3l′configurations are analyzed and the contributions of two-electron-one-photo(TEOP)radiative transitions to the DR cross sections are also investigated,such as 1s2s^(2)→1s^(2)2p,due to the strong configuration interactions.Our theoretical results appear to be in excellent agreement with the previous and recent experimental measurements.展开更多
The development of a detuning system for the precision control of electron energy is a major challenge when electron targets are used in ion-storage rings.Thus,a high-precision,high-voltage,detuning system was develop...The development of a detuning system for the precision control of electron energy is a major challenge when electron targets are used in ion-storage rings.Thus,a high-precision,high-voltage,detuning system was developed for the electron target of a high-intensity heavy-ion accelerator facility-spectrometer ring(HIAF-SRing)to produce accurate electron-ion relative energies during experiments.The system consists of auxiliary,and high-voltage detuning power supplies.The front stage of the auxiliary power supply adopts an LCC resonant converter operating in the soft-switching state and an LC filter for a sinusoidal waveform output in the post-stage.The detuning power supply is a high-voltage pulse amplifier(HVPA)connected with a high-voltage DC(HVDC)module in series.In this paper,the design and development of the detuning system are described in detail,and the test bench is presented.The test results demonstrated that the detuning system conforms to the technical specifications of the dielectronic recombination(DR)experiment.Finally,a Fe15+DR spectrum was measured using the detuning system.The experimental data demonstrated a good experimental resolution and verified the reliability and feasibility of the design.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. U1932207, 11904371, and 12104437)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB34020000)
文摘Dielectronic recombination(DR)is one of the dominant electron-ion recombination mechanisms for most highly charged ions(HCIs)in cosmic plasmas,and thus,it determines the charge state distribution and ionization balance therein.To reliably interpret spectra from cosmic sources and model the astrophysical plasmas,precise DR rate coefficients are required to build up an accurate understanding of the ionization balance of the sources.The main cooler storage ring(CSRm)and the experimental cooler storage ring(CSRe)at the Heavy-Ion Research Facility in Lanzhou(HIRFL)are both equipped with electron cooling devices,which provide an excellent experimental platform for electron-ion collision studies for HCIs.Here,the status of the DR experiments at the HIRFL-CSR is outlined,and the DR measurements with Na-like Kr25^(+)ions at the CSRm and CSRe are taken as examples.In addition,the plasma recombination rate coefficients for Ar12^(+),14^(+),Ca14^(+),16^(+),17^(+),Ni19^(+),and Kr25^(+)ions obtained at the HIRFL-CSR are provided.All the data presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00092.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10376026 and 10434100）, and the Foundation of Center of Theoretical Nuclear Physics of National Laboratory of Heavy Ion Accelerator of Lanzhou, China.
文摘Based on the multi-configuration Dirac-Fock method, this paper has made theoretical calculations for the dielectronic recombination cross-sections and the high-n dielectronic satellites to Kα resonance line in helium-like aluminium ions. It is found that high-n dielectronic satellites are seriously mixed with resonance line, which leads to a significant increase in both the apparent width and the intensity of Kα resonance line. They also induce a positional shift of Kα resonance line.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10676025 and 10976019)
文摘The KLL dielectronic recombination （DR） processes of ions from highly charged helium-like to oxygen-like krypton, iodine and barium ions are studied systematically in the relativistic distorted-wave approximation with configuration interaction. The KLL DR resonant energies, the corresponding resonant strengths and the theoretical spectra for each highly charged ion species are obtained. The results accord well with other available values. The behaviour of KLL resonant strengths for He-like ions with atomic number Z is analysed.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 1179041,11025417,and 10979007） the NSAF （Grant No. 10876043）
文摘The relativistic configuration interaction method is employed to calculate the dielectronic recombination（DR） cross sections of helium-like krypton via the 1s2lnl ＇（n = 2,3,...,15） resonances.Then,the resonant transfer excitation（RTE） processes of Kr 34＋ colliding with H,He,H 2,and CH x（x = 0-4） targets are investigated under the impulse approximation.The needed Compton profiles of targets are obtained from the Hartree-Fock wave functions.The RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the target.For H 2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l ＇ to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H 2.For CH x（x = 0-4） targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CH x,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the hydrogen.However,further comparison of the individual orbital contributions of C（2p,2s,1s） and CH 4（1t 2,2a 1,1a 1） to the RTE cross sections shows that the molecular effects induce differences of about 25.1%,19.9%,and 0.2% between 2p-1t 2,2s-2a 1,and 1s-1a 1 orbitals,respectively.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0402300)the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.U1732133,11320101003,11611530684,and 11604003)
文摘The electron–ion recombination for phosphorus-like^（112） Sn^（35＋）has been measured at the main cooler storage ring of the Heavy Ion Research Facility in Lanzhou, China, employing an electron–ion merged-beams technique. The absolute total recombination rate coefficients for electron–ion collision energies from 0 e V–14 e V are presented. Theoretical calculations of recombination rate coefficients were performed using the Flexible Atomic Code to compare with the experimental results. The contributions of dielectronic recombination and trielectronic recombination on the experimental rate coefficients have been identified with the help of the theoretical calculation. The present results show that the trielectronic recombination has a substantial contribution to the measured electron–ion recombination spectrum of^（112）Sn^（35＋）. Although a reasonable agreement is found between the experimental and theoretical results the precise calculation of the electron–ion recombination rate coefficients for M-shell ions is still challengeable for the current theory.
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFA0402300)National Natural Science Foundation of China (NSFC) (Grant Nos. 11904293, 11874051)。
文摘Armed with four different steady-state collisional-radiative(CR) models,we investigated the effect of dielectronic recombination(DR) on the charge-state distribution in laser-produced silicon plasma. To assess this effect,we performed a series of temporally resolved spectra of highly charged Si ions in the extreme ultraviolet region.Ab initio calculations of the DR rate coefficients were done for Si^(6+)–Si^(4+) ions. We also analyzed the evolution of the collisional ionization, radiative recombination, three-body recombination, photo-ionization, and DR rate coefficients as a function of electron temperature. The electron temperature and electron density for different delay times were obtained by comparing the normalized experimental and simulated spectra. The ion fraction and average charge state from the four different CR models were also obtained. The results indicate that the DR process has a greater influence in the stage of plasma evolution that cannot be neglected in plasma diagnoses.
基金supported by the National Natural Science Foundation of China (Grant No 60054402)
文摘This paper analyses the effect of configuration complex on dielectronic recombination （DR） process in highly ionized plasmas （Xe^26＋, Dy^38＋, W^46＋） by using the multiconfiguration relativistic Hartree-Fock method. Resonant and nonresonant radiative stabilizing transitions and decays to autoionizing levels followed by radiative cascades are included. Collisional transitions following electron capture are neglected. The remarkable difference between the isoelectronic trend of the rate coefficients for DR through 3d^94l4l′ and through 3d^94l5l′ is emphasized. The trend of DR through 3d^94l4l′ shows irregularities at relatively low temperature due to the progressive closing of DR channels as atomic number Z increases.
基金supported by the National Natural Science Foundation of China (Grant No 10574029)the Chinese Association of Atomic and Molecular Data and National High-Tech ICF Committee in Chinasupported by Shanghai Leading Academic Discipline Project (Grant No B107)
文摘Ab initio calculation of the total dielectronic recombination （DR） rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration interaction. The contributions to the total DR rate coefficients are explicitly calculated from the complexes of Ni-like tantalum：3s^23p^63d3/2^33d5/2^6n′l′,3s^23p^53d^10n′l′,3s3p^63d^10n′l′,3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′ and 3s3p^63d^94ln′l′ with n′≤25, and 3s^23p^63d^85ln′l′ with n′≤9.The l′and n′ dependences of partial DR rate coefficients are investigated. The contributions from higher n^complexes are evaluated by a level-by-level extrapolation method. The total DR rate coefficients mainly come from the complex series 3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′and are fitted to an empirical formula with high accuracy. Comparison of the present results with those of other works shows that the previously published data underestimate significantly the DR rates of Co-like tantalum.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10774122 and 10876028)the Natural ScienceFoundation of Gansu Province,China(Grant No.1010RJZA014)the Foundation of Northwest Normal University,China(Grant No.NWNU-KJCXGC-03-72)
文摘In this work, the KLL dielectronic recombination （DR） processes of highly charged He-like to O-like xenon ions are studied systematically by using a DR program, which is based on the multi-configuration Dirac-Fock （MCDF） method. The KLL DR resonant energies and the corresponding resonant strengths are calculated, emphasizing especially the effect of the Breit interaction on the DR strengths. The theoretical KLL DR spectra are obtained and compared with the latest experimental results obtained in the Shanghai Electron Beam Ion Trap.
基金supported by the International Atomic Energy Agency(No.16266)National Natural Science Foundation of China(Nos.91126007,11064012)
文摘Accurate data for dielectronic recombination of tungsten ions are essential in the modeling of tungsten impurity transport and radiative power loss in International Thermonuclear Experimental Reactor （ITER）. Theoretical calculations have been made for dielectronic recombi- nation （DR） rate coefficients of Br-like tungsten ions using a flexible relativistic atomic code （FAC） from i eV to 50 keV. Level-by-level calculations are carried out for evaluating the contributions to DR through all the relevant Kr-like tungsten ions autoionizing inner-shell excited configuration complexes： （3s23p63d10）-14s24p5nlntl＇ （n = 4-5, n＇ = 4-100,l＇ = 0-8）, （4s24pS）-lnln＇l＇ （n = 4-6, n＇ = 4-100, l＇ = 0-12）. Comparison of the rate coefficients for 3s, 3p, 3d, 4s and 4p subshell excitations shows that the 4p subshell excitation dominates over the whole temperature region, 4s subshell excitation at low temperature and 3p, 3d subshell excitations at high temperature can not be neglected. In order to facilitate simple applications, the total DR rate coefficient, △n = 0,1 and 2 core excitations DR rate coefficients are fitted to an empirical formula.
基金supported by the National Key Research and Development Program of China under Grant No.2017YFA0402300
文摘Dielectronic recombination is an important process in high temperature plasmas. In the present work, the KLn （n=L, M, N and O） DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai electron beam ion trap using a fast electron beam energy scanning method. The experiment uncertainty reaches about 6% with significant improvement of statistics. A relativistic configuration interaction calculation is also made. Theoretical results agree with the experiment results within 15% in most cases.
基金National Natural Science Foundation of China(11320101003), External Cooperation Program of Chinese Academy of Sciences(GJHZ1305)
文摘Dielectronic recombination (DR) is an important electron–ion recombination process. This process is generallyconsidered to occur in two steps,e??+Aq+![A(q??1)+]![A(q??1)+]+nhv ; (1) where in the first step a free electron is captured simultaneously with the excitation of a bound electron. In the second step the doubly-excited ion is stabilized by emitting photons.
基金Major State Basic Research Development Program of China (973 Program, 2010CB832902) and by NationalNature Science Foundation of China (10979007 and 10704076). S.F.Z is grateful to the CAS-MPS doctor training program. The authorsthank the cooperation from Max-Planck Institute for Nuclear Physics, Heidelberg.
文摘Young's double-slit interference is a clear manifestation of the wave character of light. The feasibility of an atomicversion of Young's double slit experiment for matter waves in ion-atom collisions was first discussed theoreticallyby Tuan and Gerjuoy in 1960[1]. They studied capture processes in collisions of protons with H2 and suggestedthat diffraction of the protons from the two atomic centers of the molecule could lead to interference effects. Suchinterference effects are more difficult to observe in ionization processes, since there the final state of the collisioninvolves at least three unbound particles. The experimental observation of this process is particularly challengingbecause the determination of the phase angle in such processes is not straightforward.
文摘The main cooler storage ring (CSRm) equipped with an electron-cooler creates an ideal platform for dielectronicrecombination (DR) experiments. In order to fully understand our DR experimental setup and especially the electronenergy detuning system, we have performed a DR calibration experiment using the Li-like argon ions at theCSRm. The Ar15+ has a simple electronic structure so the DR spectrum can be calculated with an ultra-highprecision and compared with the existing experimental data. The experiment was carried out at the relative energyfrom 0 to 32 eV that includes all DR resonances associated with 2s1=2 ! 2p1=2 and most of the 2s1=2 ! 2p3=2excitations.
基金National Natural Science Foundation of China(11320101003), External Cooperation Program of Chinese Academy of Sciences(GJHZ1305)
文摘The total recombination rate coefficients of lithium-like 36Ar15+ ions have been measured by employing the electron-ion merged-beams technique at the heavy ion storage ring CSRm at IMP[1]. Fig. 1 (a) shows the DR spectrum for electron energy from 0 to 35 eV in the center-of-mass (c.m.) frame involving all the DR resonances associated with 2s1=2!2p1=2 and 2s1=2!2p3=2 excitations.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 1179041,11025417,and 10979007)the NSAF (Grant No. 10876043)
文摘The relativistic configuration interaction method is employed to calculate the dielectronic recombination(DR) cross sections of helium-like krypton via the 1s2lnl ’(n = 2,3,...,15) resonances.Then,the resonant transfer excitation(RTE) processes of Kr 34+ colliding with H,He,H 2,and CH x(x = 0-4) targets are investigated under the impulse approximation.The needed Compton profiles of targets are obtained from the Hartree-Fock wave functions.The RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the target.For H 2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l ’ to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H 2.For CH x(x = 0-4) targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CH x,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the hydrogen.However,further comparison of the individual orbital contributions of C(2p,2s,1s) and CH 4(1t 2,2a 1,1a 1) to the RTE cross sections shows that the molecular effects induce differences of about 25.1%,19.9%,and 0.2% between 2p-1t 2,2s-2a 1,and 1s-1a 1 orbitals,respectively.
文摘The knowledge of accurate ionization and recombination rates of heavy ions is crucial for the study of X-ray lasers and inertia confine fusion ( ICF).The dielectronic recombination rates of Cu-like Ta44+ (1s22s22p63s23p63d104s1) ion through the (3d1041n’1’n’=4,5) configurations are given.The remarkable difference between the isoelectronic trends of the rate coefficients for dielectronic recombination through 3d104141’ and 3d104151’ is emphasized.
文摘The storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination （DR） experiments. In order to fulfill the requirement of DR measurements at the main Cooler Storage Ring, a detuning system for the precision control of the relative energy between the ion beam and the electron beam has been installed on the electron cooler device. The test run using 7.0 MeV/u C6＋ beam was performed with recording the Schottky spectra and the ion beam currents. The influence of pulse heights and widths of the detuning voltage on the ion beam was analyzed. For the small pulse height, the experimental results from the Schottky spectra were in good agreement with the theoretical results. The frequency shift in the Schottky spectra was significantly reduced for the short pulse width. For the large pulse height, an oscillation phenomenon was observed and some effective ways to reduce the oscillation were pointed out. The detailed description of the phenomenon and the theoretical model based on the plasma oscillation was discussed in this paper. The overall results show that the new detuning system works properly, and could fulfill the requirements of future DR experiment.
基金supported by the Chinese National Foundation of Sciences(Grant Nos.10344001 and 10174009)the Science and Technology Foundation of Chinese Academy of Engineering Physics,and National High-Tech ICF Committee in China。
文摘Ab initio calculations of dielectronic recombination(DR)processes from the ground state 1s 2 of He-like argon ion through doubly excited states 1s2snl,1s2pnl(n=2 to 9)of Li-like argon ions are performed using the multi-configuration HatreeFock method with relativistic correction.The theoretical method and its corresponding computation will be outlined.For higher doubly excited states with n>9,the scaling law is used to extrapolate the Auger and radiative transition rates.The total and stateto-state cross sections with corresponding rate coefficients in the temperature from 102 eV to 106 eV are presented,as well as the DR strengths for all the separate resonances.Moreover,peculiarities of the DR from doubly excited 1s2s3l′configurations are analyzed and the contributions of two-electron-one-photo(TEOP)radiative transitions to the DR cross sections are also investigated,such as 1s2s^(2)→1s^(2)2p,due to the strong configuration interactions.Our theoretical results appear to be in excellent agreement with the previous and recent experimental measurements.
文摘The development of a detuning system for the precision control of electron energy is a major challenge when electron targets are used in ion-storage rings.Thus,a high-precision,high-voltage,detuning system was developed for the electron target of a high-intensity heavy-ion accelerator facility-spectrometer ring(HIAF-SRing)to produce accurate electron-ion relative energies during experiments.The system consists of auxiliary,and high-voltage detuning power supplies.The front stage of the auxiliary power supply adopts an LCC resonant converter operating in the soft-switching state and an LC filter for a sinusoidal waveform output in the post-stage.The detuning power supply is a high-voltage pulse amplifier(HVPA)connected with a high-voltage DC(HVDC)module in series.In this paper,the design and development of the detuning system are described in detail,and the test bench is presented.The test results demonstrated that the detuning system conforms to the technical specifications of the dielectronic recombination(DR)experiment.Finally,a Fe15+DR spectrum was measured using the detuning system.The experimental data demonstrated a good experimental resolution and verified the reliability and feasibility of the design.
