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In this paper, we report on optical lines of Sc-like Kr 1 5 + and Br 1 4 + observed using a low-energy electron beam ion trap. Within the spectral range of 220–590 nm, a total of 18 spectral lines from these two ions were identified, 12 of which were reported for the first time. To determine the energy levels, the multi-configuration Dirac–Hartree–Fock method and relativistic many-body perturbation theory are employed. The excitation energies for the 19 lowest levels arising from 3 d 3 ground configuration of Kr 1 5 + and Br 1 4 + ions are presented. Comparing the theoretical wavelengths with the experimental values, a good agreement is observed with an average deviation of less than 1.1%. However, for a few lines, discrepancies larger than 2.0% are observed. The present experimental results could be reference data for further theoretical investigations of the multi-valence electron ions. [ABSTRACT FROM AUTHOR]

This study presents the investigation of magnetic dipole transition lines of W13+ ions in the wavelength range of 200–700 nm at a low-energy electron beam ion trap. Seventeen lines emitted from W13+ ions have been observed with three being reported experimentally for the first time. The atomic structure calculation and spectra simulation of W13+ ions have been carried out using the multiconfiguration Dirac–Hartree–Fock method combined with the relativistic configuration interaction approach and the collisional–radiative model, respectively. The theoretical calculations are in reasonable agreement with the experimental observations, and most of the observed lines have been identified. [ABSTRACT FROM AUTHOR]

Spectral lines of the magnetic-dipole transition between the 3 d 2 D 3 / 2 , 5 / 2 levels of K-like Kr17+, Zr21+, Nb22+, Mo23+, and Ru25+ ions were measured in a compact electron beam ion trap. By means of dedicated calibration methods, the transition wavelengths of Kr17+, Zr21+, and Mo23+ ions reduce uncertainties by at least one order of magnitude and the wavelengths of Nb22+ and Ru25+ ions are measured for the first time at a few ppm level. In addition, the fine-structure energy splittings were systematically calculated using the multiconfiguration Dirac–Hartree–Fock method combined with the relativistic configuration interaction approach. The contributions of the core-valence and core-core electron correlations, the Breit interaction and QED effect were discussed in detail. The results show that it is essential to include deep core-valence correlation of L -shell and core-core valence correlation of 3 p subshell to obtain an agreement better than 0.15% with existing experimental values. The calculation model can be performed to predict the wavelength within a high accuracy for a wide range of potassium-like ions. [ABSTRACT FROM AUTHOR]

The wavelengths and transition rates of W40+-W42+ ions within the range of 40–140 Å, have been calculated using the Flexible Atomic Code of the Dirac-Fock-Slater method with a central potential. We investigated the charge state distribution of W38+-W45+ ions at different temperatures by constructing an appropriate rate equation and demonstrate the importance of the dielectronic recombination process. Additionally, we simulated the emission spectra of W40+-W42+ ions in a Tokamak plasma environment using collisional-radiative modeling. Our findings demonstrate strong agreement with experimental results and other related theoretical investigations. Finally, we propose certain pairs of transition lines as diagnostic tools for plasma temperature and density, leveraging the correlation between line intensity ratio and electron temperature and density. [ABSTRACT FROM AUTHOR]

The new magnetic refrigeration (MR) technology, which uses the magnetocaloric effect (MCE) of materials for refrigeration, has shown apparent advantages over the compression refrigeration of freon and other gases. Therefore, how to obtain materials with excellent magnetic entropy change near room temperature is of great significance for the realization of MR. In order to achieve high Tc of a Gd-based amorphous alloy, Gd45Co50Al5 amorphous alloy with good room temperature MCE was selected, and a series of Gd45Co50−xFexAl5 (x = 2, 5, 10) amorphous alloys were prepared by adding Fe instead of Co. In this paper, the effect of Fe addition on the Curie temperature, and the magnetic entropy change in the alloys, were studied thoroughly. The results show that the Curie temperature is increased to 281 K by adding 5% Fe elements, which is mainly related to the enhanced 3d-3d interaction of transition elements caused by Fe addition, and the maximum value of magnetic entropy change is 3.24 J/(kg·K) under a field of 5 T. The results are expected to provide guidance for further improving the room temperature MCE of Gd-based amorphous alloys. [ABSTRACT FROM AUTHOR]

Abstract: In this report, a brief description of the current progress at the Shanghai EBIT project is presented. This is followed by a short discussion of the measurement of various [...]

The properties and spectrum of the highly charged tungsten ions draw more and more attention, due to its potential application in the next generation fusion reactor. The transition wavelength and rate of the magnetic-dipole transition between the levels of the ground configuration of W53+ ion in the range of 10 − 20 nm were calculated by Dirac–Fock–Slater (DFS) method with a local central potential and Multi-Configuration Dirac-Hartree-Fock (MCDHF) method, respectively. The results are consistent with the previous EBIT experimental data and other theoretical data. A collisional-radiative model was constructed, and the spectrum of magnetic-dipole transition of W53+ ion observed on EBIT (Y. Ralchenko et al., Phys. Rev. A. 83 , 032517, 2011) was reproduced theoretically. Another two new transitions near the wavelength of 16.683 nm and 18.018 nm are also assigned to the M1 transition of W53+ ion. • The EBIT spectrum of W53+ ion was reproduced and analyzed by CRM with accurate atomic data. • The new M1 transition between the ground configuration of W53+ ions were assigned to the experimental spectrum. • The MCDHF transition wavelength was used instead of DFS results to get better agreement with the experiments. [ABSTRACT FROM AUTHOR]