X-ray observations of medium Z H- and He-like ions with satellites from C-Mod tokamak plasmas

Rice, J.E.; Reinke, M.L.; Ashbourn, J. M. A.; Gao, C.; Bitter, M.; Delgado‐Aparicio, L.; Hill, K. W.; Howard, Nathan; Hughes, J. W.; Safronova, U. I.

doi:10.1088/0953-4075/48/14/144013

Cited by 16 publications

(18 citation statements)

References 80 publications

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“…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

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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.

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Section: Introductionmentioning

confidence: 99%

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

Wang

et al. 2017

A&A

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“…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

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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.

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“…On Alcator C-Mod, a multi-pulse LBO system has been used for transient impurity studies for several years [27,[33][34][35][36]. Here, we consider experiments where a CaF 2 film was ablated and calcium (Z Ca = 20) transport was studied by diagnosing impurity emission with a combination of spectroscopic measurements.…”

Section: Methodsmentioning

confidence: 99%

Inference of Experimental Radial Impurity Transport on Alcator C-Mod: Bayesian Parameter Estimation and Model Selection

Sciortino,

Howard,

Marmar

et al. 2020

Preprint

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We present a fully Bayesian approach for the inference of radial profiles of impurity transport coefficients and compare its results to neoclassical, gyrofluid and gyrokinetic modeling. Using nested sampling, the Bayesian Impurity Transport InferencE (BITE) framework can handle complex parameter spaces with multiple possible solutions, offering great advantages in interpretative power and reliability with respect to previously demonstrated methods. BITE employs a forward model based on the pySTRAHL package, built on the success of the well-known STRAHL code [Dux, IPP Report, 2004], to simulate impurity transport in magnetically-confined plasmas. In this paper, we focus on calcium (Ca, Z=20) Laser Blow-Off injections into Alcator C-Mod plasmas. Multiple Ca atomic lines are diagnosed via high-resolution X-ray Imaging Crystal Spectroscopy and Vacuum Ultra-Violet measurements. We analyze a sawtoothing I-mode discharge for which neoclassical and turbulent (quasilinear and nonlinear) predictions are also obtained. We find good agreement in diffusion across the entire radial extent, while turbulent convection and density profile peaking are estimated to be larger in experiment than suggested by theory. Efforts and challenges associated with the inference of experimental pedestal impurity transport are discussed.

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X-ray observations of medium Z H- and He-like ions with satellites from C-Mod tokamak plasmas

Cited by 16 publications

References 80 publications

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

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

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

Inference of Experimental Radial Impurity Transport on Alcator C-Mod: Bayesian Parameter Estimation and Model Selection

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