On the interpolation of isoelectronic data

Burgess, A.; Chidichimo, M. C.; Tully, J. A.

doi:10.1051/aas:1997119

Cited by 58 publications

(95 citation statements)

References 4 publications

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“…7 of Aggarwal and Keenan [30]. It may be noted that if for practical reasons calculations of Ω are performed only up to a limited range of energy then the high energy limits for a range of transitions can be invoked through the expressions suggested by Burgess and Tully [25]. However, there is no such need in the present work as calculations for Ω have been performed up to a reasonably high energy range, as noted in section 5.…”

Section: Effective Collision Strengthsmentioning

confidence: 89%

“…Collision strengths (Ω) are related to the more commonly known parameter collision cross section (σ ij , πa 0 2 ) by the following relationship [25]:…”

Section: Collision Strengthsmentioning

confidence: 99%

“…Since the threshold energy region is dominated by numerous closed-channel (Feshbach) resonances, values of Ω need to be calculated in a fine energy mesh to accurately account for their contribution. Furthermore, in a plasma electrons have a wide distribution of velocities, and therefore values of Ω are generally averaged over a Maxwellian distribution as follows [25]:…”

Section: Effective Collision Strengthsmentioning

confidence: 99%

See 2 more Smart Citations

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

Aggarwal¹,

Keenan²

2012

Phys. Scr.

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We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in Be-like Ti XIX. The grasp (General-purpose Relativistic Atomic Structure Package) is adopted for calculating energy levels and radiative rates. 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 reported for all E1, E2, M1 and M2 transitions among the lowest 98 levels of the n ≤ 4 configurations. Additionally, theoretical lifetimes are listed for all 98 levels. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 10 7.7 K. Comparisons are made with similar data obtained from the Flexible Atomic Code (fac) to highlight the importance of resonances, included in calculations with darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for forbidden transitions, are also discussed.2

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Section: Effective Collision Strengthsmentioning

confidence: 89%

“…Collision strengths (Ω) are related to the more commonly known parameter collision cross section (σ ij , πa 0 2 ) by the following relationship [25]:…”

Section: Collision Strengthsmentioning

confidence: 99%

Section: Effective Collision Strengthsmentioning

confidence: 99%

See 1 more Smart Citation

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

Aggarwal¹,

Keenan²

2012

Phys. Scr.

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“…Ballance et al 17 calculated electron-impact excitation data for electron temperatures ranging from 0.043 to 43.1 eV; we have extended this temperature range to 430.87 eV by means of the high energy Born limit of the collision strength. 25 We apply the Burgess and Tully 25 approach for extending the temperature ranges by means of the ADAS215 code, 19 this more accurate approach gives us very different results for the higher electron temperature regions, than the simple spline extrapolation used by the ADAS208 code we applied for the previous helium line ratio calculation. 22 Electron-impact ionization rate coefficients were taken from CCC calculations.…”

Section: Atomic Datamentioning

confidence: 99%

Hybrid time dependent/independent solution for the He I line ratio temperature and density diagnostic for a thermal helium beam with applications in the scrape-off layer-edge regions in tokamaks

et al. 2012

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Spectroscopic studies of line emission intensities and ratios offer an attractive option in the development of non-invasive plasma diagnostics. Evaluating ratios of selected He I line emission profiles from the singlet and triplet neutral helium spin systems allows for simultaneous measurement of electron density (ne) and temperature (Te) profiles. Typically, this powerful diagnostic tool is limited by the relatively long relaxation times of the 3S metastable term of helium that populates the triplet spin system, and on which electron temperature sensitive lines are based. By developing a time dependent analytical solution, we model the time evolution of the two spin systems. We present a hybrid time dependent/independent line ratio solution that improves the range of application of this diagnostic technique in the scrape-off layer (SOL) and edge plasma regions when comparing it against the current equilibrium line ratio helium model used at TEXTOR.

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“…However, the present theoretical calculations only provide collision strengths at a few energy values, so that some interpolation/extrapolation technique is required in order to properly take into account the energy dependence of collision strengths. In the present work, we have adopted the method described by Burgess and Tully [37] to extrapolate collision strengths to the high-and low-energy limit. This method has been used in our earlier papers [1][2][3][4][5][6] and details are given there.…”

Section: Atomic Datamentioning

confidence: 99%

Atomic data and spectral line intensities for Ni XVII

Bhatia

Landi

2011

Atomic Data and Nuclear Data Tables

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a b s t r a c tElectron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ni XVII. We include in the calculations the 23 lowest configurations, corresponding to 159 fine-structure levels: 3l3l 0 , 3l4l 00 , and 3s5l 000 , with l, l 0 = s,p,d, l 00 = s, p, d, f, and l 000 = s, p, d. Collision strengths are calculated at five incident energies for all transitions at varying energies above the threshold of each transition. One additional energy, very close to the threshold of each transition, has also been included. Calculations have been carried out using the Flexible Atomic Code in the distorted wave approximation. Additional calculations have been performed with the University College London suite of codes for comparison. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates of the present work, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10 8 À 10 14 cm À3 and at an electron temperature of log T e (K) = 6.5, corresponding to the maximum abundance of Ni XVII. Spectral line intensities are calculated, and their diagnostic relevance is discussed. This dataset will be made available in the next version of the CHIANTI database.

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On the interpolation of isoelectronic data

Cited by 58 publications

References 4 publications

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

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

Hybrid time dependent/independent solution for the He I line ratio temperature and density diagnostic for a thermal helium beam with applications in the scrape-off layer-edge regions in tokamaks

Atomic data and spectral line intensities for Ni XVII

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