State-selective charge exchange cross sections in collisions of highly-charged sulfur ions with helium and molecular hydrogen

The state-selective cross section data are useful for understanding and modeling the x-ray emission in celestial observations.In the present work,using the cold target recoil ion momentum spectroscopy,for the first time we investigated the state-selective single electron capture processes for S^(q+)–He and H_(2)(q=11–15)collision systems at an impact energy of q×20 keV and obtained the relative state-selective cross sections.The results indicate that only a few principal quantum states of the projectile energy level are populated in a single electron capture process.In particular,the increase of the projectile charge state leads to the population of the states with higher principal quantum numbers.It is also shown that the experimental averaged n-shell populations are reproduced well by the over-barrier model.The database is openly available in Science Data Bank at 10.57760/sciencedb.j00113.00091.

Atomic structure and collision dynamics with highly charged ions

The research progresses on the investigations of atomic structure and collision dynamics with highly charged ions based on the heavy ion storage rings and electron ion beam traps in recent 20 years are reviewed.The structure part covers test of quantum electrodynamics and electron correlation in strong Coulomb field studied through dielectronic recombi-nation spectroscopy and VUV/x-ray spectroscopy.The collision dynamics part includes charge exchange dynamics in ion-atom collisions mainly in Bohr velocity region,ion-induced fragmentation mechanisms of molecules,hydrogen-bound and van de Waals bound clusters,interference,and phase information observed in ion-atom/molecule collisions.With this achievements,two aspects of theoretical studies related to low energy and relativistic energy collisions are presented.The applications of data relevant to key atomic processes like dielectronic recombination and charge exchanges involving highly charged ions are discussed.At the end of this review,some future prospects of research related to highly charged ions are proposed.

Absolute dielectronic recombination rate coefficients of highly charged ions at the storage ring CSRm and CSRe

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.

Ionization and single electron capture in collision of highly charged Ar^(16+) ions with helium

This paper uses the two-centre atomic orbital close-coupling method to study the ionization and the single electron capture in collision of highly charged Ar^16＋ ions with He atoms in the velocity range of 1.2-1.9 a.u.. The relative importance of single ionization （SI） to single capture （SC） is explored. The comparison between the calculation and experimental data shows that the SI/SC cross section ratios from this work are in good agreement with experimental data. The total single electron ionization cross sections and the total single electron capture cross sections are also given for this collision. The investigation of the partial electron capture cross section shows a general tendency of capture to larger n and l with increasing velocity from 1.2 to 1.9 a.u..

Theoretical study of electron-impact broadening for highly charged Ar XV ion lines

Spectral line widths produced by collisions between charged particles and emitters are of special interest for precise plasma spectroscopy.The highly charged Ar XV ion is demonstrated to have strong intrashell electron interactions,which manifest as an atomic system with many resonance structures,due to the quasi-degeneracy of orbital energies.In this paper we use the relativistic R-matrix method to investigate the electron-impact broadening of highly charged Ar XV ion spectral lines under the impact approximation.It is found that the results considering resonance structures are significantly different from those of the distorted wave approach.Furthermore,we propose a new empirical formula with a correction term to take into account the effect of resonances for electron-impact widths over a relatively wide range of plasma conditions.The corresponding fitting parameters of the new empirical formula for all 47 calculated transitions are also given with an estimated accuracy within 1%,which should be convenient for practical applications.The dataset that supported the findings of this study is available in Science Data Bank,with the link https://doi.org/10.57760/sciencedb.j00113.00101.

Peripheral collisions of highly charged ions with metal clusters

Within the framework of the dynamical classical over-barrier model,the soft collisions between slow highly charged ions（SHCIs） Ar 17＋ and the large copper clusters under large impact parameters have been studied in this paper.We present the dominant mechanism of the electron transfer between SHCIs and a large metal cluster by computational simulation.The evolution of the occupation of projectile ions,KL x satellite lines,X-ray yields,Auger electron spectrum and scattering angles are provided.

Benchmarking calculations of excitation energies and transition properties with spectroscopic accuracy of highly charged ions used for the fusion plasma and astrophysical plasma

Atomic radiative data such as excitation energies, transition wavelengths, radiative rates, and level lifetimes with high precision are the essential parameters for the abundance analysis, simulation, and diagnostics in fusion and astrophysical plasmas. In this work, we mainly focus on reviewing our two projects performed in the past decade. One is about the ions with Z■30 that are generally of astrophysical interest, and the other one is about the highly charged krypton(Z = 36)and tungsten(Z = 74) ions that are relevant in research of magnetic confinement fusion. Two different and independent methods, namely, multiconfiguration Dirac–Hartree–Fock(MCDHF) and the relativistic many-body perturbation theory(RMBPT) are usually used in our studies. As a complement/extension to our previous works for highly charged tungsten ions with open M-shell and open N-shell, we also mainly focus on presenting and discussing our complete RMBPT and MCDHF calculations for the excitation energies, wavelengths, electric dipole(E1), magnetic dipole(M1), electric quadrupole(E2), and magnetic quadrupole(M2) transition properties, and level lifetimes for the lowest 148 levels belonging to the 3l3configurations in Al-like W61+. We also summarize the uncertainties of our systematical theoretical calculations, by cross-checking/validating our datasets from our RMBPT and MCDHF calculations, and by detailed comparisons with available accurate observations and other theoretical calculations. The data are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.10569.

Charge state effect on the K-shell ionization of iron by xenon ions near the Bohr velocity

Fe K-shell ionization cross sections induced by 2.4-6.0 MeV Xe^20＋ are measured and compared with different binary- encounter-approximation （BEA） models. The results indicate that the BEA model corrected both by the Coulomb repulsion and by the effective nuclear charge （Zeff） agrees well with the experimental data. Comparison of Fe K-shell X-ray emission induced by 5 MeV xenon ions with different initial charge states （20＋, 22＋, 26＋, 30＋） verifies the applicability of the effective nuclear charge （Zeff） correction for the BEA model. It is found that Zeff correction is reasonable to describe direct ionization induced by xenon ions with no initial M-shell vacancies. However, when the M shell is opened, the Zeff corrected BEA model is unable to explain the inner-shell ionization, and the electron transfer by molecular-orbital promotion should be considered.

Measurements of absolute electron capture cross sections in He^(2+)–He and Ne^(8+)–O_(2'), N_(2'), CH_4 collisions

The total absolute cross sections of single-and double-electron capture (SEC and DEC) in the collisions of He^(2+)with He and Ne^(8+)with O_(2),N_(2),and CH_(4) were studied in the energy ranges 3.5–50 keV/u and 2.8–40 keV/u,respectively.Through a deep analysis of the experimental systematic uncertainties in the measurement procedure and data evaluation,the error in the experimental results of the SEC cross sections is less than 9%.Within the uncertainties,the present results of the He^(2+)–He collision show good consistency with previous measurements,validating the experimental system and paving the way for precise measurements of EC cross sections for a variety of ions and neutral gases.The present measurements allow for a test of EC theory and provide crucial EC cross section data for the establishment of plasma models in fusion research and astrophysical X-ray studies.

Neutralization process of Xe^q＋ ion grazing on Al（111） surface

A code has been developed to simulate the neutralization and grazing process of slow highly charged ion Xe^q＋ on Al（111） surface under the classical-over-the-barrier model. The image energy gain of Xeq＋ ions are calculated and compared with experiment data. The simulation results of image energy gain are in good agreement with the experiment data. Meanwhile, in the present work, the reflection coefficient of incident Xe^q＋ on Al（111） surface as a function of the incidence angle, energy and charge state is also studied.

Recoil Momentum of Target Ions in Collisions of Ar^(6+)+CO_2 at Energies Below 300 eV/u

The collision dynamics and fragmentation process of molecule by highly charged ion impact for single electron capture processes at the low energies below 1 keV/u were studied. The collision energy dependence of the recoil momentum was obtained experimentally and compared it with those calculated by a theoretical model using a deflection function with polarization potential. A fairly good agreement between the measured and calculated results was reached. This suggests that the polarization potential plays a crucial role in the low-energy region.

Modified Classical Over Barrier Model for Multi-Charged Ion in Collisions with Multiple Electron Target at Energies Below 1 keV/u

Charge transfer cross sections for Kr^q＋ with Ne are calculated quantitatively by using modified classical over barrier model in order to clarify energy dependence of charge transfer cross sections in low energy region. Essential of this model is taking the induced dipole potential into consideration. As a result, this calculation can reproduce systematic energy dependence of experimental results. This suggests that the bending trajectory of the projectile due to an induced dipole potential should be considered to describe pictures of collisions at low energy regime below 1 keV/u.

HYDROGEN DISTRIBUTION AND DIFFUSION BEHAVIOUR IN HIGH PRESSURE HYDROGEN CHARGED AUSTENITIC STEEL BY IMMA

The hydrogen distribution curve along cross-section of high pressure hydrogen charged spec- imens of 21Cr-7Ni-9Mn-N austenitic steel was obtained quantitatively by IMMA(Ion Microprobe Mass Analyzer).Thus the hydrogen solubility and diffusivity may be measured, and the hydrogen permeability and other parameters may be calculated indirectly.The hydrogen distribution in specimens either long-term aged in air or in electron beam weld seam after high pressure hydrogen charging was also examined.

Charge Breeding Simulations in a Hollow Electron Beam

Charge breeding technique is used for RIB （radioactive ion beam） production in order of optimizing the re-acceleration of the radioactive isotopes produced by a primary beam in a thick target. Charge breeding is achieved by means of a device capable of increasing the ion charge state from 1＋ to a desired value n＋. In some experiments, a continuous RIB of a given energy may be required. To reach this goal, a charge breeding device based on a hollow gun EBIS （electron beam ion source） has been proposed by the author recently. That EBIS, in principle, can be capable to realize a CW （continuous wave） operation. A sufficiently high focusing magnetic field could reduce to zero the hole radius in the EBIS electron beam. However, a smaller efficiency in the ion charge state increase should be expected. A code developed for studying the ion selective containment in a EBIS has been modified and used to simulate the ion charge state breeding. The effects of the hollow electron beam on the breeding rate have been studied.

Production of highly charged argon ions from a room temperature electron beam ion trap

In this work, highly charged ions have been extracted from the advanced Electron Beam Ion Source （EBIS-A） developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden. The charge state distributions of ions extracted from the EBIS-A are measured in the pulse and leaky modes under different operation conditions. Aris＋ ions with current of 2 pA are produced and extracted in the leaky mode. 3×10^5 Ar^18＋ ions per pulse are extracted in the pulse mode. The ion charge state distribution is a function of the ionization time.

High voltage generator circuit with low power and high efficiency applied in EEPROM

This paper presents a low power and high efficiency high voltage generator circuit embedded in electrically erasable programmable read-only memory（EEPROM）.The low power is minimized by a capacitance divider circuit and a regulator circuit using the controlling clock switch technique.The high efficiency is dependent on the zero threshold voltage（V_（th）） MOSFET and the charge transfer switch（CTS） charge pump.The proposed high voltage generator circuit has been implemented in a 0.35μm EEPROM CMOS process.Measured results show that the proposed high voltage generator circuit has a low power consumption of about 150.48μW and a higher pumping efficiency（83.3%） than previously reported circuits.This high voltage generator circuit can also be widely used in low-power flash devices due to its high efficiency and low power dissipation.

Enhance the performance of polymer solar cells via extension of the flanking end groups of fused ring acceptors

Two new fused ring electron acceptors(FREAs)IDT-IC-T and IDT-IC-B with thienyl or phenyl substituents at the terminal INCN unit are synthesized.Theoretical calculations indicate that the two acceptors dominantly favor an intermolecularπ-πstacking between the flanking terminal groups.The twist angle between the aryl substituent and INCN unit has a significant influence on theπ-πstacking distance of terminal unit.IDT-IC-T with a smaller twist angle has a shorterπ-πstacking distance than that of IDT-IC-B with a larger twist angle.In addition,extending the conjugation also affects the blend film morphology.IDT-IC-T and IDT-IC-B based photoactive films show appropriate nanoscale phase separations;whereas,blend films based on the parent compound IDT-IC show large-size acceptor domains.As expected,PBDB-T:IDT-IC-T blend films show higher and more balanced electron and hole mobilities.Moreover,these two acceptors present a good charge-transport connectivity arising from the extended conjugation and the increased intermolecular overlapping.Ultimately,IDT-IC-T demonstrates the highest electron mobility(1.47×10^(-4)cm^2V^(-1)s^(-1))and the best power conversion efficiency(PCE)of 9.43%.As for IDT-IC,which only shows an electron mobility of 7.33×10^(-5)cm^2V^(-1)s^(-1)and a PCE of 5.82%.These findings provide a facile and effective way to improve the photovoltaic performance.

Effect of Zr^(4+)on piezoelectric,dielectric and ferroelectric properties of barium calcium titanate lead-free ceramics

Ba_(0.85)Ca_(0.15)(Ti1−xZrx)O_(3)(BCTZ)ceramics with x=0.05,0.10,_(0.15),0.20,0.25,0.30 were prepared by the solid-state reaction method.Calcination of the powders was carried out at 1100°C for 4 h and the green pellets were sintered at 1400°C for 2 h.X-ray diffraction patterns of the sintered pellets showed tetragonal splitting up to x=0.10 while the mixture of the rhombohedral/cubic phase appeared at higher ZrO_(2)concentrations.Maximum piezoelectric charge constant d33=510 pC/N and strain(S=0.103%)were measured for BCT doped by 0.10 mol ZrO_(2).Dielectric constant,remnant polarization and saturation polarization also found maxima for this composition.The Curie temperature(TC)of the compositions decreased with increase in ZrO_(2)concentration and reached 98°C,87°C and 36°C at x=0.05,0.10,_(0.15)mol,respectively.The remaining compositions have TC below the room temperature;therefore,they can be used for subzero/cryogenic applications.The scanning electron microscopy study revealed an increase in grain size with increase in ZrO_(2)concentration and confirmed the complete solubility of ZrO_(2)in the crystal lattice.Overall,low ZrO_(2)-doped BCT compositions with high d33 could be suitable for low temperature(<80°C)applications.