Dirac<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>R</mml:mi></mml:math>-matrix calculations for the electron-impact excitation of neutral tungsten providing noninvasive diagnostics for magnetic confinement fusion

Smyth, Ryan; Ballance, C. P.; Ramsbottom, Catherine; Johnson, Curtis A.; Ennis, D.A.; Loch, S. D.

doi:10.1103/physreva.97.052705

Cited by 13 publications

(20 citation statements)

References 33 publications

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“…The black curve is from [14], red crosses are from [15]. In Figures 7 and 8 we present similar evidence of accuracy and quality for neutral tungsten, with data from Smyth et al [18] (Figures 3 and 6 in their paper). Figure 7 shows effective collision strengths for four diagnostically important transitions in W I and a comparison with a less-sophisticated plane-wave Born calculation, while Figure 8 contains the spectrum from the CTH experiment compared with those generated using these new atomic data.…”

Section: Heavier Systemssupporting

confidence: 84%

“…Observed spectrum from the CTH experiment (solid blue line) compared to the theoretical data of[18] (red dashed line). Vertical green lines are the PECs for W I for an electron temperature of 8 eV and electron density of 1 × 10 12 cm −3 .…”

mentioning

confidence: 99%

“…Solid black lines with crosses are from[18] and the red lines with dots are from a plane-wave Born calculation based on calculations by[19].…”

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confidence: 99%

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Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data

et al. 2018

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The spectra currently emerging from modern ground- and space-based astronomical instruments are of exceptionally high quality and resolution. To meaningfully analyse these spectra, researchers utilise complex modelling codes to replicate the observations. The main inputs to these codes are atomic data such as excitation and photoionisation cross sections, as well as radiative transition probabilities, energy levels, and line strengths. In this publication, the current capabilities of the numerical methods and computer packages used in the generation of these data are discussed. Particular emphasis is given to Fe-peak species and the heavy systems of tungsten and molybdenum. Some of the results presented to highlight certain issues and/or advances have already been published in the literature, while other sections present new recently evaluated atomic data for the first time.

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Section: Heavier Systemssupporting

confidence: 84%

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confidence: 99%

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Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data

et al. 2018

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“…The radiated power of neutral tungsten is predicted to be most intense in the UV region and a total of 29 W I emission lines are observed and identified between the two experiments. Of the observed W I lines, 20 have not previously been reported in fusion relevant plasmas. The set of newly identified W I lines includes an intense line at 265.65 nm which is driven from the same metastable level as the widely utilized 400.88 nm.…”

Section: Discussionmentioning

confidence: 77%

Advances in neutral tungsten ultraviolet spectroscopy for the potential benefit to gross erosion diagnosis

Johnson¹,

Ennis²,

Loch³

et al. 2019

Plasma Phys. Control. Fusion

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A spectral survey of tungsten emission in the ultraviolet region has been completed in the DIII-D tokamak and the CTH torsatron to assess the potential benefit of UV emission for the diagnosis of gross W erosion. A total of 29 W I spectral lines are observed from the two experiments using survey spectrometers between 200-400 nm with level identifications provided based on a structure calculation for many of the excited states that produce strong emission lines. Of the 29 observed lines, 20 have not previously been reported in fusion relevant plasmas, including an intense line at 265.65 nm which could be important for benchmarking the frequently exploited line at 400.88 nm. Nearly all of the observed spectral lines decay down to one of the six lowest energy levels for neutral W, which are likely to be long-lived metastable states. The impact of metastable level populations on the W I emission spectrum and any erosion measurement utilizing a spectroscopic technique is potentially significant. Nevertheless, the high density of W I emission in the UV region allows for the possibly of determining the relative metastable fractions and plasma parameters local to the erosion region. Additionally, the lines observed in this work could be used to perform multiple independent gross erosion measurements, leading to more accurate diagnosis of gross tungsten erosion.

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“…This was obtained using P. Norrington's updated 1 version of the fully relativistic General-Purpose Relativistic Atomic Structure Program (GRASP 0 ) [6,7]. GRASP 0 has recently been used to model atomic systems as complex as neutral molybdenum [8] and neutral tungsten [9] and the quality of the collisional and radiative data obtained verified by comparison of synthetic spectra and experiment. For this reason, GRASP 0 was a reasonable choice of structure package for this calculation.…”

Section: Atomic Structurementioning

confidence: 99%

Towards the Provision of Accurate Atomic Data for Neutral Iron

et al. 2018

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The rich emission and absorption line spectra of Fe I may be used to extract crucial information on astrophysical plasmas, such as stellar metallicities. There is currently a lack, in quality and quantity, of accurate level-resolved effective electron-impact collision strengths and oscillator strengths for radiative transitions. Here, we discuss the challenges in obtaining an accurate model of the neutral iron atom and compare our theoretical fine-structure energy levels with observation for several increasingly large models. Radiative data is presented for several transitions for which the atomic data is accurately known.

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DiracR-matrix calculations for the electron-impact excitation of neutral tungsten providing noninvasive diagnostics for magnetic confinement fusion

Cited by 13 publications

References 33 publications

Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data

Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data

Advances in neutral tungsten ultraviolet spectroscopy for the potential benefit to gross erosion diagnosis

Towards the Provision of Accurate Atomic Data for Neutral Iron

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