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The electron correlation effects and Breit interaction as well as Quantum Electro-Dynamics (QED) effects were expected to have important contribution to the energy level and transition properties of heavy highly charged ions. The ground states [Ne]3s 23p 63d 2 and first excited states [Ne]3s 23p 53d 3 of W54+ ion have been studied by using Multi-Configuration Dirac-Fock method with the implementation of Grasp2K package. A restricted active space method was employed to investigate the correlation contribution from different models. The Breit interaction and QED effects were taken into account in the relativistic configuration interaction calculation with the converged wavefunction. It is found that the correlation contribution from 3s and 3p orbital have important contribution to the energy level, transition wavelength and probability of the ground and the first excited state of W54+ ion., source:Ding, X., Sun, R., Koike, F. et al. Correlation, Breit and Quantum Electrodynamics effects on energy level and transition properties of W54+ ion. Eur. Phys. J. D 71, 73 (2017). https://doi.org/10.1140/epjd/e2017-70829-y, source:https://doi.org/10.1140/epjd/e2017-70829-y

Extreme ultraviolet (EUV) optical transitions of lanthanide highly charged ions have been studied. The [Ni]4s24p–[Ni]4s24d and [Ni]4s24p–[Ni]4s4p2 transition lines of galliumlike lanthanide elements have been spectroscopically measured in large helical device (LHD) plasma and electron-beam ion trap (EBIT) plasma. The wavelengths for Eu ions agreed within 0.03% between the LHD and EBIT measurements. Due to the enhancement of spin-orbit interactions along with the increase of atomic number Z in 4p atomic orbitals, energy splitting between 4p1/2 and 4p3/2 orbitals increases significantly from lanthanum to lutetium, causing the crossing of Z-dependent wavelength curves. The spectral line positions and strengths are theoretically calculated by means of the multiconfiguration Dirac-Fock method. The mixing of the [Ni]4s24d and [Ni]4s4p2 configurations leads to an avoided crossing in the apparent wavelength curves. The configuration mixing makes both the [Ni]4s24p–[Ni]4s24d and [Ni]4s24p–[Ni]4s4p2 lines well visible in the EUV spectra near the level crossing point. The levels are found to cross between Z=62 and 63., source:Fumihiro Koike, Chihiro Suzuki, Izumi Murakami, Daiji Kato, Naoki Tamura, and Nobuyuki Nakamura Phys. Rev. A 105, 032802, source:https://doi.org/10.1103/PhysRevA.105.032802

We have systematically observed extreme ultraviolet (EUV) spectra from highly charged ions of nine lanthanide elements with atomic numbers from 60–70 in optically thin plasmas produced in the Large Helical Device (LHD). Discrete spectral features with isolated lines from relatively higher charge states around Cu-like ions are observed under high temperature conditions around 2 keV,while narrowed quasicontinuum features from charge states around Ag-like ions are observed under low temperature conditions below 1 keV. The positions of the lines and the quasicontinuum features systematically move to shorter wavelengths as the atomic number increases. The wavelengths of the main peaks in the quasicontinuum features agree well with those of singlet transitions of Pd-like ions reported previously. We have easily identified discrete spectral lines from Cu-like and Ag-like ions, some of which are experimentally identified for the first time in the LHD. Their wavelengths are compared with theoretical calculations using a GRASP family of atomic codes. The theoretical valuesare synthesized to the LHD experimental data for the cases of Ag- and Pd-like ions., source:Atoms 2018, 6(2), 24; https://doi.org/10.3390/atoms6020024, source:https://doi.org/10.3390/atoms6020024

We have observed a number of different types of extreme ultraviolet (EUV) spectra from highly charged gadolinium (Gd), terbium (Tb) and dysprosium (Dy) ions in optically thin plasmas produced in the Large Helical Device at the National Institute for Fusion Science. Temporal changes in EUV spectra in the 6–9 nm region subsequent to the injections of solid pellets were measured by a grazing incidence spectrometer. The spectra rapidly change from discrete features into unresolved transition arrays (UTAs) following a drop in the electron temperature after the heating power is reduced. In particular, extremely narrowed UTA features, which comprise spectral lines of Ag-like, Pd-like and neighboring ion stages, are observed when the peak electron temperature is less than 0.45 keV due to the formation of hollow plasmas. Some discrete spectral lines of Cu-like and Ag-like ions have been identified in the high and low temperature plasmas, respectively, some of which are experimentally identified for the first time., source:C Suzuki et al 2015 J. Phys. B: At. Mol. Opt. Phys. 48 144012, source:https://doi.org/10.1088/0953-4075/48/14/144012

We have constructed a collisional-radiative (CR) model for W27+ ions including 226 configurations with n ≤ 9 and ł ≤ 5 for spectroscopic diagnostics. We newly include recombination processes in the model and this is the first result of extreme ultraviolet spectrum calculated for recombining plasma component. Calculated spectra in 40–70 Å range in ionizing and recombining plasma components show similar 3 strong lines and 1 line weak in recombining plasma component at 45–50 Å and many weak lines at 50–65 Å for both components. Recombination processes do not contribute much to the spectrum at around 60 Å for W27+ ion. Dielectronic satellite lines are also minor contribution to the spectrum of recombining plasma component. Dielectronic recombination (DR) rate coefficient from W28+ to W27+ ions is also calculated with the same atomic data in the CR model. We found that larger set of energy levels including many autoionizing states gave larger DR rate coefficients but our rate agree within factor 6 with other works at electron temperature around 1 keV in which W27+ and W28+ ions are usually observed in plasmas., source:Murakami, I., Sasaki, A., Kato, D. et al. Collisional-radiative model including recombination processes for W27+ ion. Eur. Phys. J. D 71, 246 (2017). https://doi.org/10.1140/epjd/e2017-80099-4, source:https://doi.org/10.1140/epjd/e2017-80099-4, identifier:0000-0001-7544-1773