Dependence of the probabilities of the electric-multipole electron transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mi mathvariant="normal">W</mml:mi><mml:mrow><mml:mn>24</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>on multipolarity

Gaigalas, Gediminas; Rudzikas, Zenonas; Rynkun, Pavel; Alkauskas, Audrius

doi:10.1103/physreva.83.032509

Cited by 5 publications

(5 citation statements)

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“…In [13,16], the configuration interaction effects among the levels of up to three configurations are investigated. There are only a few works where energy levels and radiative transition probabilities for the tungsten ions with more than 3 electrons in f shell have been studied in the Dirac-Fock approach [32,33].…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigation of spectroscopic properties of W25+

Alkauskas

Rynkun

Gaigalas

et al. 2014

Journal of Quantitative Spectroscopy and Radiative Transfer

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Energy levels and emission spectra of W 25+ ion have been studied by performing the large-scale relativistic configuration interaction calculations. Configuration interaction strength is used to determine the configurations exhibiting the largest influence on the 4f 3 , 4d 9 4f 4 , 4f 2 5s, 4f 2 5p, 4f 2 5d, 4f 2 5f , 4f 2 5g, and 4f 2 6g configuration energies. It is shown that correlation effects are crucial for the 4f 2 5s → 4f 3 transition which in single-configuration approach occurs due to the weak electric octupole transitions. As well, the correlation effects affect the 4f 2 5d → 4f 3 transitions by increasing transition probabilities by an order. Corona model has been used to estimate the contribution of various transitions to the emission in a low-density electron beam ion trap (EBIT) plasma. Modeling in 10-30 nm wavelength range produces lines which do not form emission bands and can be observed in EBIT plasma.

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Section: Introductionmentioning

confidence: 99%

Theoretical investigation of spectroscopic properties of W25+

Alkauskas

Rynkun

Gaigalas

et al. 2014

Journal of Quantitative Spectroscopy and Radiative Transfer

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“…Some sophisticated theoretical investigations have also been performed for complex tungsten ions [13][14][15]. Gaigalas et al made a large-scale calculation on the spectroscopic properties of W 24+ ions in both relativistic and non-relativistic theoretical frameworks taking valencevalence and core-valence correlation effects into account [13,14]. Ralchenko et al measured the M1 transitions in highly charged 3d n ions of tungsten.…”

Section: Introductionmentioning

confidence: 99%

Ab initiomulti-configuration Dirac–Fock calculation of M1 visible transitions among the ground state multiplets of the W^{26 +}ion

Ding

Koike

Murakami

et al. 2011

J. Phys. B: At. Mol. Opt. Phys.

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Tungsten (W) is currently considered to be a good candidate for the surface material of the divertor and main chamber plasma facing components in future magnetic fusion devices due to its refractory properties. However, using tungsten as a shield material, tungsten atoms and ions will inevitably be introduced into the plasma as an intrinsic impurity. Due to their large radiation loss, tungsten impurity ions will be deleterious for the achievement of the ignition in magnetically confined fusion. To diagnose, understand and control the influx of impurity tungsten ions, a thorough knowledge of atomic physics on tungsten ions will be helpful.Recently, we observed visible spectra of moderately charged tungsten ions using a compact EBIT (coBIT) at electron energies of 200-1000 eV and found many previously unreported lines. , which is one of the simplest examples of a complex configuration with multiple 4f electrons. For such a heavy element with nuclear charge Z=74, a relativistic treatment is desired. Meanwhile, the moderately ionized ions still have a substantial number of electrons, which repel each other via the Coulomb force and lead to a complex electron correlation.The present calculation was performed in the framework of the multi-configuration Dirac-Fock (MCDF) method with the implementation of GRASP2K 1) and RATIP packages. In order to take the most important electron correlation effects into account, a systematical single and double substitution from 4d and 4f orbital to a restricted active space (AS) was employed. The Breit interaction, vacuum polarization and self-energy effects are estimated by the relativistic configuration interaction calculation considering the Dirac-Fock-Breit Hamiltonian matrix in terms of configuration state functions with a fixed orbital basis set. The Breit interaction was usually considered in the low-frequency limit.To investigate the correlation contributions, two strategies of calculation for the structure of the ground state of W 26+ are implemented. The method A considers only the VV (valence-valence) and CV (core-valence) correlations while the method B considers also CC (core-core) correlation contributions. 2) Ding X.B. et al.:

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“…In the last few years a significant improvement has been achieved in the theoretical approaches, in particular by the development of large-scale relativistic configuration-interaction (CI) methods taking into account electron correlation effects. Such a technique was employed for M1 transitions in Ag-and Cd-like tungsten [17,22], electric-multipole transitions in Sn-like tungsten [23,24], and for transitions from low-lying levels in Ni-like tungsten [25]. An extended experimental and theoretical data base on the tungsten ions can be found in Refs.…”

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confidence: 99%

High-resolution tungsten spectroscopy relevant to the diagnostic of high-temperature tokamak plasmas

et al. 2018

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The x-ray transitions in Cu-and Ni-like tungsten ions in the 5.19-5.26Å wavelength range that are relevant as a high-temperature tokamak diagnostic, in particular for JET in the ITER-like wall configuration, have been studied. Tungsten spectra were measured at the upgraded Shanghai-Electron Beam Ion Trap operated with electron-beam energies from 3.16 to 4.55 keV. High-resolution measurements were performed by means of a flat Si 111 crystal spectrometer equipped by a CCD camera. The experimental wavelengths were determined with an accuracy of 0.3-0.4 mÅ. The wavelength of the ground-state transition in Cu-like tungsten from the 3p 5 3d 10 4s4d [(3/2,(1/2,5/2) 2 ] 1/2 level was measured. All measured wavelengths were compared with those measured from JET ITER-like wall plasmas and with other experiments and various theoretical predictions including COWAN, RELAC, multiconfigurational Dirac-Fock (MCDF), and FAC calculations. To obtain a higher accuracy from theoretical predictions, the MCDF calculations were extended by taking into account correlation effects (configuration-interaction approach). It was found that such an extension brings the calculations closer to the experimental values in comparison with other calculations. ‡ See author list of "X. Litaudon et al., Nucl. Fusion 97, 102001 (2017)." for highly ionized tungsten ions up to Cu-like (W 45+ ) and Na-like (W 63+ ), respectively [19,20].The experimental spectroscopic studies of tungsten ions were supported by extensive theoretical considerations (see, e.g., Ref.[21] and references therein). In the last few years a significant improvement has been achieved in the theoretical approaches, in particular by the development of large-scale relativistic configuration-interaction (CI) methods taking into account electron correlation effects. Such a technique was employed for M1 transitions in Ag-and Cd-like tungsten [17,22], electric-multipole transitions in Sn-like tungsten [23,24], and for transitions from low-lying levels in Ni-like tungsten [25]. An extended experimental and theoretical data base on the tungsten ions can be found in Refs. [26][27][28].Recently, in measurements on the Joint European Torus (JET) with the ITER-like wall (ILW) configuration (beryllium wall and tungsten divertor) [29,30], the W 45+ and W 46+ (3p-4d) x-ray lines were observed. From analysis of tungsten line intensities, it was found that the W concentration is ∼10 −5 for the ELMy H-mode JET plasmas (edge-localized-mode of plasma operation with high-energy confinement times) with 2.0-2.5 MA current, 2.7 T toroidal magnetic field and 14-18 MW neutral beam injection (NBI) power. Tungsten concentration determined from the W 45+ line was systematically lower than that obtained from W 46+ by ∼20% for different types of JET discharges [7]. It was further shown that, in order to reproduce the experimental spectra in the 5.192-5.232Å wavelength range at the measured electron 2469-9926/2018/97(5)/052501 (9) 052501-1

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Dependence of the probabilities of the electric-multipole electron transitions inW24+on multipolarity

Cited by 5 publications

References 10 publications

Theoretical investigation of spectroscopic properties of W25+

Theoretical investigation of spectroscopic properties of W25+

Ab initiomulti-configuration Dirac–Fock calculation of M1 visible transitions among the ground state multiplets of the W^{26 +}ion

High-resolution tungsten spectroscopy relevant to the diagnostic of high-temperature tokamak plasmas

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Dependence of the probabilities of the electric-multipole electron transitions inW24+on multipolarity

Cited by 5 publications

References 10 publications

Theoretical investigation of spectroscopic properties of W25+

Theoretical investigation of spectroscopic properties of W25+

Ab initiomulti-configuration Dirac–Fock calculation of M1 visible transitions among the ground state multiplets of the W26 +ion

High-resolution tungsten spectroscopy relevant to the diagnostic of high-temperature tokamak plasmas

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Ab initiomulti-configuration Dirac–Fock calculation of M1 visible transitions among the ground state multiplets of the W^{26 +}ion