Ionization energies of tungsten ions: W2+ through W71+

Kramida, Alexander; Reader, Joseph

doi:10.1016/j.adt.2006.03.002

Cited by 78 publications

(63 citation statements)

References 30 publications

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“…As the excitation energy varies from 152 eV in the top panel to 293 eV in the bottom panel, the evolution of emission bands may be followed, but individual features associated with specific charge states are difficult to identify at this resolution. Although having an uncertainty of a few tens of electron volts in the EBIT excitation energy, the ionization energy of 141.2 eV for Ho-like W 7+ [3] suggests that the complex tungsten emission starts with the Dy-like W IX spectrum.…”

Section: Discussionmentioning

confidence: 99%

“…The electron-beam energy was varied in the range from 31 up to 293 eV, which should cover many of the low tungsten charge states [3]. Figures 1 and 2 show observed spectra at ten beam energies.…”

Section: Survey Measurementsmentioning

confidence: 99%

“…Concentration measurements of tungsten impurity ions in the divertor volume are thus critical for assessing tungsten flux rates. Based on the tungsten ionization energies [3], it can be expected that, neglecting transport, approximately the first ten charge states will have high abundances. For divertor plasmas, it is thus the atomic data for few-times ionized tungsten that are needed.…”

Section: Introductionmentioning

confidence: 99%

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Extreme Ultraviolet Spectra of Few-Times Ionized Tungsten for Divertor Plasma Diagnostics

Clementson

Lennartsson

Beiersdörfer

2015

Atoms

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The extreme ultraviolet (EUV) emission from few-times ionized tungsten atoms has been experimentally studied at the Livermore electron beam ion trap facility. The ions were produced and confined during low-energy operations of the EBIT-I electron beam ion trap. By varying the electron-beam energy from around 30-300 eV, tungsten ions in charge states expected to be abundant in tokamak divertor plasmas were excited, and the resulting EUV emission was studied using a survey spectrometer covering 120-320 Å. It is found that the emission strongly depends on the excitation energy; below 150 eV, it is relatively simple, consisting of strong isolated lines from a few charge states, whereas at higher energies, it becomes very complex. For divertor plasmas with tungsten impurity ions, this emission should prove useful for diagnostics of tungsten flux rates and charge balance, as well as for radiative cooling of the divertor volume. Several lines in the 194-223 Å interval belonging to the spectra of five-and seven-times ionized tungsten (Tm-like W VI and Ho-like W VIII) were also measured using a high-resolution spectrometer.

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Section: Discussionmentioning

confidence: 99%

Section: Survey Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extreme Ultraviolet Spectra of Few-Times Ionized Tungsten for Divertor Plasma Diagnostics

Clementson

Lennartsson

Beiersdörfer

2015

Atoms

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“…The ground configurations of tungsten ions were taken from the latest revised data [17], they coincide with configurations obtained in single configuration quasirelativistic approximation, except q = 12, where the calculation gives the lowest level corresponding to a 4f 13 5s 2 5p configuration instead of a 4f 14 5s 2 configuration following from experimental data.…”

Section: Methods Of Calculationmentioning

confidence: 99%

Closing of Coster–Kronig transitions and variation of fluorescence and Auger yields in isonuclear sequence of tungsten

Kučas

Karazija²

2011

Lith. J. Phys.

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The dependence of Auger yields, partial and total Auger widths of levels, total radiative widths, and fluorescence yields on the ionisation degree is considered for ions of tungsten. The calculations are performed for the Ni subshells in the single configuration quasirelativistic approximation. The intervals of ionisation stages at which the Coster-Kronig transitions are energetically possible or partially possible are determined. It is shown that the partially possible Coster-Kronig transitions between overlapping initial and final configurations can take place in several neighbouring ions successively. According to our calculation results, the nonradiative decay of vacancies in Ni subshells becomes impossible from ionisation stage q = 21. The total Auger width depends weakly on ionisation degree up to its values q = 8-11, but for higher ions changes non-monotonically due to closing of Coster-Kronig transitions. The fluorescence yield shows the similar dependence on q.

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“…In Figure 3, the comparison of tabulated ionization potentials [19] for of tungsten ions with the Thomas-Fermi model values calculated from Equation (8) is presented. As can be seen by the figure, the statistical model quite reasonably approximates the available data [19].…”

Section: Ionization Potentials and Average Chargementioning

confidence: 99%

Tungsten Ions in Plasmas: Statistical Theory of Radiative-Collisional Processes

Demura

Kadomtsev

Lisitsa

et al. 2015

Atoms

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Abstract:The statistical model for calculations of the collisional-radiative processes in plasmas with tungsten impurity was developed. The electron structure of tungsten multielectron ions is considered in terms of both the Thomas-Fermi model and the Brandt-Lundquist model of collective oscillations of atomic electron density. The excitation or ionization of atomic electrons by plasma electron impacts are represented as photo-processes under the action of flux of equivalent photons introduced by E. Fermi. The total electron impact single ionization cross-sections of ions W k+ with respective rates have been calculated and compared with the available experimental and modeling data (e.g., CADW). Plasma radiative losses on tungsten impurity were also calculated in a wide range of electron temperatures 1 eV-20 keV. The numerical code TFATOM was developed for calculations of radiative-collisional processes involving tungsten ions. The needed computational resources for TFATOM code are orders of magnitudes less than for the other conventional numerical codes. The transition from corona to Boltzmann limit was investigated in detail. The results of statistical approach have been tested by comparison with the vast experimental and conventional code data for a set of ions W k+ . It is shown that the universal statistical model accuracy for the ionization cross-sections and radiation OPEN ACCESSAtoms 2015, 3 163 losses is within the data scattering of significantly more complex quantum numerical codes, using different approximations for the calculation of atomic structure and the electronic cross-sections.

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Ionization energies of tungsten ions: W2+ through W71+

Cited by 78 publications

References 30 publications

Extreme Ultraviolet Spectra of Few-Times Ionized Tungsten for Divertor Plasma Diagnostics

Extreme Ultraviolet Spectra of Few-Times Ionized Tungsten for Divertor Plasma Diagnostics

Closing of Coster–Kronig transitions and variation of fluorescence and Auger yields in isonuclear sequence of tungsten

Tungsten Ions in Plasmas: Statistical Theory of Radiative-Collisional Processes

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