Seventh spectrum of tungsten (W vii); resonance lines of Hf v

Sugar, Jack; Kaufman, Victor

doi:10.1103/physreva.12.994

Cited by 56 publications

(60 citation statements)

References 7 publications

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“…This drift is assumed to be due to the thermal motions of the EBIT-spectrometer setup and limits the measurement accuracy. To lessen the position uncertainty for the majority of the observed lines, the previously known Er-like W 6+ line from the (5p 6 ) 0 -(5p 1/2 5p 4 3/2 5d 3/2 ) 1 transition at 216.219(5) Å, as measured by Sugar and Kaufman [13], was used as a reference line to which the wavelength scale of the first oxygen calibration spectrum was anchored by shifting it 18 mÅ. Comparing the first oxygen spectrum to the second, there is a relative difference between them of nearly 2 mÅ between the edges of the detector.…”

Section: High-resolution Measurementsmentioning

confidence: 99%

“…Recently, photoionization experiments were carried out on tungsten charge states up to five-times ionized at the ALS synchrotron by Müller et al [12]. Sugar and Kaufman measured VUV and EUV lines from the closed-shell Er-like W 6+ ion using a sliding-spark light source [13]. The W VII spectrum was further investigated by Wyart et al, who identified a number of lines in the EUV [14].…”

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: High-resolution Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Clementson

Lennartsson

Beiersdörfer

2015

Atoms

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“…These coincidences are confirmed by high resolution scans (not shown) with the EBIT source [5] 2 operating at an electron beam energy of 128 ± 10 eV. In particular, the line at 21.6 nm, dominating the EBIT data, is a strong line of W VII [12][13][14], while the calculated O V line intensity at nearly the same wavelength is predicted to be relatively weak 5 . Because tabulated spectra of W VIII and W IX are not available [12,13,15], these tests cannot be made on the shorter wavelength portion of the data.…”

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confidence: 57%

Interpretation of EUV emissions observed by Mills et al.

Phelps

Clementson

2012

Eur. Phys. J. D

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Abstract. An explanation of the so-called hydrino continuum emissions proposed by Mills and Lu, most recently in [Eur. Phys. J. D 64, 65 (2011)], is presented using conventional atomic, plasma, and discharge physics. It is argued that the observed EUV emissions during their pulsed discharges originate from transitions in ions sputtered or evaporated from the electrodes. Such an interpretation removes their justification for the introduction of hydrino particles.Recently, Mills and Lu have published extreme ultraviolet (EUV) spectra from pulsed discharges, which they claim prove the existence of so-called hydrino atoms (hydrogen atoms with states having a fractional principal quantum number) [1][2][3][4]. The discharges were produced using various fill gases and cathode materials. The observed spectra could not be explained by Mills et al. using conventional physics, which allowed them to interpret the data as evidence for their hydrino model. In the present paper, it is argued that the observed spectra are, in fact, emissions from low charge-state ions sputtered or evaporated from the electrodes plus some impurity ion emission. The continuum appearance is explained as being made up of densely spaced lines that are not fully resolved. Specific points are:Mills et al. claim [1][2][3][4] there are no differences in the observed discharge spectra when different electrode materials are used. In Figures 1 through 3 spectra have been digitized 1 from plots of Mills et al. [1][2][3][4] for emission observed with cathodes made of tungsten (W), molybdenum (Mo), and tantalum (Ta). These traces show instead that the spectra differ considerably with electrode material. The dependence on material is especially clear in Figures 1a and 1b, where discharges with W and Mo cathodes using a hydrogen (H 2 ) fill gas are compared.Mills et al. [1][2][3][4] further state that the observed emission cannot be explained as line emission by atoms or ions from the metal electrodes. Here it is shown that much of a e-mail: avp@jila.colorado.edu 1 Because requested original data tabulations have not been made available, the data shown for Mills et al. are obtained by digitizing figures selected for minimum diffusiveness and non-overlapping curves from the referenced publications and "secured" preprint files. Thus, for the data of reference [4] in Figures 1 and 2, the pixel width seen by the digitizer software is larger than the nominal spectrometer resolution of 0.05 nm.the emission can indeed be explained as line radiation from low charge states of sputtered or evaporated high-Z metal ions. In Figure 1a the spectrum of Mills et al. is plotted together with W spectra observed by Clementson et al. [5] 2 from an electron beam ion trap (EBIT). The data were acquired using a grazing-incidence instrument with a resolution of 0.04 nm full width half maximum (FWHM) at an EBIT electron-beam energy of 150 ± 10 eV. This energy is high enough to create W ions with charge states up to 8+ [6]. Very similar spectra at lower resolution (not shown) have been ...

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“…This lack of knowledge was underlined by Kramida and Shirai [14] who compiled all the classified energy levels and spectral lines of multiply ionized tungsten atoms from W 2+ to W 73+ . In this compilation, it was reminded that it was by the way uncertain whether the ground state of W VIII was 4f P°3/2, making this ion the only known case of p and f orbitals competing for the ground state, as previously noted by Sugar and Kaufman [15]. An isoelectronic study was not even of great help to solve the problem since it was found that the ground configuration was 4f [15] asserted that the ground state of W VIII was probably 4f above it.…”

Section: Available Atomic Data In W VIIImentioning

confidence: 96%

“…In this compilation, it was reminded that it was by the way uncertain whether the ground state of W VIII was 4f P°3/2, making this ion the only known case of p and f orbitals competing for the ground state, as previously noted by Sugar and Kaufman [15]. An isoelectronic study was not even of great help to solve the problem since it was found that the ground configuration was 4f [15] asserted that the ground state of W VIII was probably 4f above it. This assumption was in agreement with the calculations performed earlier by Carlson et al [16] who showed that 4f was the least-bound orbital of W VII.…”

Section: Available Atomic Data In W VIIImentioning

confidence: 96%

Detailed Analysis of Configuration Interaction and Calculation of Radiative Transition Rates in Seven Times Ionized Tungsten (W VIII)

Deprince

Quinet

2015

Atoms

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Abstract:A new set of oscillator strengths and transition probabilities for EUV spectral lines of seven times ionized tungsten (W VIII) is reported in the present paper. These results have been obtained using the pseudo-relativistic Hartree-Fock (HFR) method combined with a semi-empirical optimization of the radial parameters minimizing the discrepancies between computed energy levels and available experimental data. The final physical model considered in the calculations has been chosen further to a detailed investigation of the configuration interaction in this atomic system characterized by complex configurations of the type 4f nl (nl = 5d, 6s).

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Seventh spectrum of tungsten (W vii); resonance lines of Hf v

Cited by 56 publications

References 7 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

Interpretation of EUV emissions observed by Mills et al.

Detailed Analysis of Configuration Interaction and Calculation of Radiative Transition Rates in Seven Times Ionized Tungsten (W VIII)

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