Radial profiles of ground-state transitions of heliumlike argon from the Alcator-<i>C</i>tokamak

Rice, J. E.; Marmar, E.; Källne, E.; Källne, J.

doi:10.1103/physreva.35.3033

Cited by 64 publications

(42 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These spectra, obtained for viewing chords tangent to r/a ∼ 0.9, include the resonance line, w (1s2p 1 P 1 -1s 2 1 S 0 , 3949.28 mÅ), the intercombination lines, x and y (1s2p 3 P 2 -1s 2 1 S 0 , 3965.99 mÅ, and 1s2p 3 P 1 -1s 2 1 S 0 , 3969.40 mÅ) and the forbidden line, z (1s2p 3 S 1 -1s 2 1 S 0 , 3994.28 mÅ). At the low electron temperatures of the edge plasma, the upper levels of these transitions were populated by radiative recombination of H-like argon [43], which was born at the plasma center, and was transported outward on the fast time scale of L-mode impurity confinement [44,45,46]. In the top frame, from an LOC plasma, the spectra from the top and bottom viewing chords have the same intensity, and it may be concluded that the edge impurity densities are up/down symmetric.…”

Section: Methodsmentioning

confidence: 99%

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Rice¹,

Gao²,

Reinke³

et al. 2013

Nucl. Fusion

155

View full text Add to dashboard Cite

Several seemingly unrelated effects in Alcator C-Mod Ohmic L-mode plasmas are shown to be closely connected: non-local heat transport, core toroidal rotation reversals, energy confinement saturation and up/down impurity density asymmetries. These phenomena all abruptly transform at a critical value of the collisionality. At low densities in the linear Ohmic confinement regime, with collisionality ν * ≤ 0.35 (evaluated inside of the q=3/2 surface), heat transport exhibits non-local behavior, core toroidal rotation is directed co-current, edge impurity density profiles are up/down symmetric and a turbulent feature in core density fluctuations with k θ up to 15 cm −1 (k θ ρ s ∼ 1) is present. At high density/collisionality with saturated Ohmic confinement, electron thermal transport is diffusive, core rotation is in the counter-current direction, edge impurity density profiles are up/down asymmetric and the high k θ turbulent feature is absent. The rotation reversal stagnation point (just inside of the q=3/2 surface) coincides with the non-local electron temperature profile inversion radius. All of these observations can be unified in a model with trapped electron mode prevalence at low collisionality and ion temperature gradient mode domination at high collisionality.

show abstract

Section: Methodsmentioning

confidence: 99%

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Rice¹,

Gao²,

Reinke³

et al. 2013

Nucl. Fusion

155

View full text Add to dashboard Cite

show abstract

“…Emission lines from the spectra of helium-like ions are often observed in the spectra of solar, stellar, and other astrophysical plasmas (Seely & Feldman 1985;Feldman et al 2000;Dere et al 2001;Ness et al 2003;Paerels & Kahn 2003;Phillips 2004;Landi & Phillips 2005;Güdel & Nazé 2009;. Spectral lines of helium-like ions are also prominent features in the X-ray spectra of tokamak and laser-produced plasmas (Hsuan et al 1987;Rice et al 1987Rice et al , 1999Rice et al , 2014Rice et al , 2015Beiersdorfer et al 1995). An analysis of spectral lines provides information on the temperature, density, and chemical composition of the plasma.…”

Section: Introductionmentioning

confidence: 99%

Electron impact excitation for He-like ions withZ= 20–42

Wang

et al. 2017

A&A

View full text Add to dashboard Cite

Aims. Spectral lines of He-like ions are among the most prominent features in X-ray spectra from a large variety of astrophysical and high-temperature fusion plasmas. A reliable plasma modeling and interpretation of the spectra require a large amount of accurate atomic data related to various physical processes. In this paper, we focus on the electron-impact excitation (EIE) process. Methods. We adopted the independent process and isolated resonances approximation using distorted waves (IPIRDW). Resonant stabilizing transitions and decays to lower-lying autoionizing levels from the resonances are included as radiative damping. To verify the applicability of the IPIRDW approximation, an independent Dirac R-matrix calculation was also performed. The two sets of results show excellent agreement. Results. We report electron impact excitation collision strengths for transitions among the lowest 49 levels of the 1snl(n ≤ 5, l ≤ (n − 1)) configurations in He-like ions with 20 ≤ Z ≤ 42. The line ratios R and G are calculated for Fe XXV and Kr XXXV. Conclusions. Compared to previous theoretical calculations, our IPIRDW calculation treats resonance excitation and radiative damping effects more comprehensively, and the resulting line emission cross sections show good agreement with the experimental observations. Our results should facilitate the modeling and diagnostics of various astrophysical and laboratory plasmas.

show abstract

“…Spectral lines of helium-like ions are also prominent features in the X-ray spectra of tokamak plasmas and laser-produced plasmas. These features arise from impurity elements (e.g., Hsuan et al 1987;Bombarda et al 1988;Beiersdorfer et al 1995;Elton et al 2000;Rosmej et al 2002;Rice et al 1987Rice et al , 1999Rice et al , 2000Rice et al , 2014Rice et al , 2015. The relative intensities Full Tables 1 and 2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A141 of spectral lines from the n = 2 shell to the ground state have been widely used in temperature and density diagnostics for solar plasma (e.g., McKenzie et al 1979;Wolfson et al 1983;Keenan et al 1984;Doyle & Keenan 1986) and tokamak plasmas (e.g., Källne et al 1983;Keenan et al 1989).…”

Section: Introductionmentioning

confidence: 99%

Energy levels and transition rates for helium-like ions withZ = 10–36

Guo

Wang

et al. 2016

A&A

View full text Add to dashboard Cite

Aims. Helium-like ions provide an important X-ray spectral diagnostics in astrophysical and high-temperature fusion plasmas. An interpretation of the observed spectra provides information on temperature, density, and chemical compositions of the plasma. Such an analysis requires information for a wide range of atomic parameters, including energy levels and transition rates. Our aim is to provide a set of accurate energy levels and transition rates for helium-like ions with Z = 10-36. Methods. The second-order many-body perturbation theory (MBPT) was adopted in this paper. To support our MBPT results, we performed an independent calculation using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Results. We provide accurate energies for the lowest singly excited 70 levels among 1snl (n ≤ 6, l ≤ (n − 1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln l (n ≤ 6, l ≤ (n − 1)) configurations of helium-like ions with Z = 10−36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. Conclusions. Our MBPT results for singly excited n ≤ 2 levels show excellent agreement with other elaborate calculations, while those for singly excited n ≥ 3 and doubly excited levels show significant improvements over previous theoretical results. Our results will be very helpful for astrophysical line identification and plasma diagnostics.

show abstract

Radial profiles of ground-state transitions of heliumlike argon from the Alcator-Ctokamak

Cited by 64 publications

References 35 publications

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Electron impact excitation for He-like ions withZ= 20–42

Energy levels and transition rates for helium-like ions withZ = 10–36

Contact Info

Product

Resources

About