Energy levels, radiative rates and electron impact excitation rates for transitions in He-like Mg XI, Al XII, P XIV and S XV

Aggarwal, K. M.; Keenan, F. P.

doi:10.1088/0031-8949/85/02/025305

Cited by 19 publications

(41 citation statements)

References 49 publications

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“…Furthermore, our MBPT energy levels and those from Savukov et al (2003) agree to by about 140 ppm, 200 ppm, and 270 ppm for Ne IX, Si XIII, and Ar XVII, respectively. Almost all the level energies calculated by Aggarwal et al (2005Aggarwal et al ( , 2008Aggarwal et al ( , 2009Aggarwal et al ( , 2010Aggarwal et al ( , 2011Aggarwal et al ( , 2012cAggarwal et al ( ,a,d,b, 2013b are lower than our MBPT values by more than 20 000 cm −1 , which corresponds to about 0.2% in the low-Z end and 300 ppm in the high-Z end. This is due to the inadequate inclusion of the electron correlation in their calculations, as pointed out above.…”

Section: Energy Levelscontrasting

confidence: 68%

“…The differences between our MBPT lifetimes and those from Savukov et al (2003) are generally smaller than 1% as well. However, and as expected, our MBPT results differ substantially from those of Aggarwal et al (2005Aggarwal et al ( , 2008Aggarwal et al ( , 2009Aggarwal et al ( , 2010Aggarwal et al ( , 2011Aggarwal et al ( , 2012cAggarwal et al ( ,a,d,b, 2013b. The largest difference is up to 70% in Na X and still as large as 15% in Kr XXXV.…”

Section: Radiative Lifetimessupporting

confidence: 58%

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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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Section: Energy Levelscontrasting

confidence: 68%

Section: Radiative Lifetimessupporting

confidence: 58%

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

Guo

Wang

et al. 2016

A&A

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“…However, these data are not very useful for comparisons because there are often anomalies in the calculated Ω, as may be seen in Fig. 6 of [39]- [40]. Nevertheless, the qualitative agreement for most transitions in all three ions is similar to that already discussed for Al X [10] and Ti XIX [11].…”

Section: Collision Strengthssupporting

confidence: 56%

Energy levels, radiative rates and electron impact excitation rates for transitions in Be-like Cl XIV, K XVI and Ge XXIX

Aggarwal¹,

Keenan²

2014

Phys. Scr.

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S This article has associated online supplementary data files Tables 4-6 and 13-15 are available only in the electronic version at stacks.iop.org/PhysScr/vol/number 1 arXiv:1409.3745v1 [astro-ph.SR] Abstract Results for energy levels, radiative rates and electron impact excitation (effective) collision strengths for transitions in Be-like Cl XIV, K XVI and Ge XXIX are reported. For the calculations of energy levels and radiative rates the General-purpose Relativistic Atomic Structure Package (grasp) is adopted, while for determining the collision strengths and subsequently the excitation rates, the Dirac Atomic R-matrix Code (darc) is used. Oscillator strengths, radiative rates and line strengths are listed for all E1, E2, M1 and M2 transitions among the lowest 98 levels of the n ≤ 4 configurations. Furthermore, lifetimes are provided for all levels and comparisons made with available theoretical and experimental results. Resonances in the collision strengths are resolved in a fine energy mesh and averaged over a Maxwellian velocity distribution to obtain the effective collision strengths. Results obtained are listed over a wide temperature range up to 10 7.8 K, depending on the ion.lines is density sensitive [2]. While these lines are in the UV range, the magnetic dipole (2s2p) 3 P o 1 -3 P o 2 line of 17 ≤ Z ≤ 20 lies in the visible [3]. In particular, lines of K XVI have been detected in solar spectra from the SERTS (solar EUV rocket telescope and spectrograph) rocket [4] as well as Hinode satellite [5]. Apart from astrophysical applications, Be-like ions are of interest in the modelling of fusion plasmas [6]. Several lines of Cl XIV and K XVI have been measured in laboratory plasmas by Huang et al [7]. Similarly, the 2s 2 1 S 0 -2s2p 1 P o 1 line of Ge XXIX at 92.8Å has been detected in the PLT (Princeton Large Torus) tokamak plasma by Stratton et al [8]. The importance of these ions has further increased with the developing ITER project. The ions which have been identified [9] for a greater interest are Al X, Cl XIV, K XVI, Ti XIX and Ge XXIX. Therefore, we have recently reported atomic data (i.e. energy levels, radiative rates and electron impact excitation rates) for Al X [10] and Ti XIX [11], and in this paper report similar results for Cl XIV, K XVI and Ge XXIX.The experimental energy levels for these ions have been compiled and critically evaluated by the NIST (National Institute of Standards and Technology) team [12], and are available at the website http://www.nist.gov/pml/data/asd.cfm. Calculations for radiative rates (A-values) have been performed by many workers [13] - [17], but are restricted to the n ≤ 3 levels. However, realising the importance of Be-like ions, many measurements have been made for their lifetimes, such as by [18]- [24]. These are helpful in assessing the accuracy of calculated A-values, as we will discuss in section 4. On the other hand, calculations for collision strengths (Ω) are very limited. For example, [13] and [25] calculated Ω for a wide range of Be-like ions with 8 ≤ Z...

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“…The average agreement between the effective collision strengths by Zhang & Sampson (1987) for transitions between n ≤ 2 levels with Aggarwal & Keenan (2012) for Mg xii and Aggarwal & Keenan (2010) for Si xiii is within 2%, except again for the 2 3 S 1 − 1 1 S 0 forbidden transition where differences as large as a factor of 2 are observed at low temperatures. On the other hand, remarkable discrepancies are found between Zhang & Sampson (1987) and Chen et al (2006) for several n ≤ 2 transitions in Ne ix at high temperatures, specially for allowed and intercombination transitions (see Fig.…”

Section: )mentioning

confidence: 69%

“…These transition-probability data sets have been shown to be accurate to better than 3% by Mendoza et al (2014). Therefore, the key benchmark is the accuracy of the effective collision strengths for these ionic species reported by Zhang & Sampson (1987), Delahaye & Pradhan (2002), Chen et al (2006), Aggarwal & Keenan (2008, 2012 and Aggarwal et al (2009Aggarwal et al ( , 2011. The evaluation of the effective collision strengths is carried out by means of the formalism developed by Burgess & Tully (1992) wherein, according to the transition type (allowed, intercombination or forbidden), the effective collision strength and electron temperature are scaled such that the temperature range 0 ≤ T e ≤ ∞ is reduced to 0 ≤ T r ≤ 1.…”

Section: Atomic Datamentioning

confidence: 99%

A benchmark of the He-like triplet for ions with 6 ≤Z≤ 14 in Maxwellian and non-Maxwellian plasmas

Rodríguez¹,

Gatuzz²,

Bautista³

et al. 2016

Mon. Not. R. Astron. Soc.

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After an extensive assessment of the effective collision strengths available to model the He-like triplet of C v, N vi, O vii, Ne ix, Mg xi and Si xiii in collisionally dominated plasmas, new accurate effective collision strengths are reported for Ne ix. The uncertainty intervals of the density and temperature diagnostics due to the atomic data errors are also determined for both Maxwell-Boltzmann and κ electron-energy distributions. It is shown that these uncertainty bands limit the temperature range where the temperature line-ratio diagnostic can be applied and its effectiveness to discern the electron-energy distribution type. These findings are benchmarked with Chandra and XMM-Newton spectra of stellar coronae and with tokamak measurements.

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Energy levels, radiative rates and electron impact excitation rates for transitions in He-like Mg XI, Al XII, P XIV and S XV

Cited by 19 publications

References 49 publications

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

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

Energy levels, radiative rates and electron impact excitation rates for transitions in Be-like Cl XIV, K XVI and Ge XXIX

A benchmark of the He-like triplet for ions with 6 ≤Z≤ 14 in Maxwellian and non-Maxwellian plasmas

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