Quenching of transition arrays through configuration mixing

Bauche, J.; Bauche‐Arnoult, C.; Klapisch, M.; Mandelbaum, P.; Schwol, J L

doi:10.1088/0022-3700/20/7/013

Cited by 86 publications

(44 citation statements)

References 14 publications

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“…Because configuration interaction can have significant effects on both transition energies and strengths [19][20][21], its absence in transitions among the RC levels could degrade the diagnostic utility of spectra from the hybrid model.…”

Section: Calculation Of Spectramentioning

confidence: 99%

Hybrid atomic models for spectroscopic plasma diagnostics

Hansen

Bauche

Bauche‐Arnoult

et al. 2007

High Energy Density Physics

160

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We propose a hybrid approach to treating atomic structure and rates in collisionalradiative models, combining the completeness of highly averaged models with the accuracy of detailed models. The hybrid scheme supplements a small subset of coronally accessible fine structure levels with a complete set of configuration-and superconfiguration-averaged levels and produces spectra based on transitions among a mix of fine-structure and relativistic configuration-averaged levels. Convenient expressions are given for obtaining rates between the fine structure and averaged levels and a technique for propagating configuration interaction from the fine structure calculations to configuration averages is described. We present results from a trial hybrid model of germanium which demonstrate the accuracy of the hybrid model for charge state distributions and spectra.

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Section: Calculation Of Spectramentioning

confidence: 99%

Hybrid atomic models for spectroscopic plasma diagnostics

Hansen

Bauche

Bauche‐Arnoult

et al. 2007

High Energy Density Physics

160

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“…Final state configuration interaction between the 4p 5 4d n+1 and 4d n-1 4f configurations causes a narrowing of the array and also causes the most intense lines to essentially overlap in energy [15][16][17]. The profile of the UTA in this type of transition is known to be sensitive to concentration of the element of interest because of opacity effects [18].…”

Section: +mentioning

confidence: 99%

“…So any advantages of using xenon, based on its gaseous nature and inherent cleanliness, must be weighed up against the disadvantages of a low density of emitting ions and the fact that the transitions involved are at least a factor of ten weaker than those occurring in the 11 nm band. Moreover the 13.5 nm wavelength of choice almost coincides with that of maximum absorption in the neutral and low ion stages [13].If instead of xenon, one considers tin, the emission arising from 4p 4f configurations causes a narrowing of the array and also causes the most intense lines to essentially overlap in energy [15][16][17]. The profile of the UTA in this type of transition is known to be sensitive to concentration of the element of interest because of opacity effects [18].…”

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confidence: 99%

UTA versus line emission for EUVL: studies on xenon emission at the NIST EBIT

Fahy¹,

Dunne²,

McKinney³

et al. 2004

J. Phys. D: Appl. Phys.

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Abstract:Spectra from xenon ions have been recorded at the NIST EBIT and the emission into a 2% bandwidth at 13.5 nm arising from 4d_5p transitions compared with that from 4d_4f and 4p_4d transitions in Xe XI and also with that obtained from the unresolved transition array (UTA) observed to peak just below 11 nm. It was found that an improvement of a factor of five could be gained in photon yield using the UTA rather than the 4d_5p emission. The results are compared with atomic structure calculations and imply that a significant gain in efficiency should be obtained using tin, in which the emission at 13.5 nm comes from a similar UTA, rather than xenon as an EUVL source material. BACKGROUND:The search for the optimum radiation source at 13.5 nm is one of the main challenges in EUV physics today. Currently the quest is to find a source with a conversion efficiency (CE) of 3% into 2% bandwidth as defined by the needs of the microelectronic industry [1]. The earliest work was performed with laser produced plasmas generated on solid targets. Kauffman et al. [2] attained a CE close to 1% into 3% bandwidth using 7.5 ns, 300 mJ frequency doubled Nd:YAG pulses focussed to a power density of 2×10 . In their work they performed an extensive survey of the emission from a large range of elements and found that the emission at the required wavelength peaked near tin. At higher power densities they noted that the intensity decreased. Shevelko et al. [4] also undertook an extensive study of the spectra of a large number of elements from laser produced plasmas with a KrF excimer laser focussed to a power density of 10 12 Wcm -2 onto planar targets including tin and found that the maximum intensity was in fact obtained for Ge and Re under these conditions. So early work already pointed to the sensitivity of the emission of specific elements to laser power density.In order to avoid the debris problems associated with solid targets other target materials were sought with strong emission in the 13-14 nm region. Jin and Richardson [5] used mass limited water ice targets, where the emission is from the O VI lines near 2 13 nm, to limit the debris. However, all of their early work with mass-limited targets produced significant levels of debris both in the form of ions and particulates of various sizes. The need to reduce particulate emission led to the choice of xenon. There is a line group between 13-14 nm in the spectrum of Xe which has been shown by a number of researchers to arise from 4d 8 _ 4d 7 5p transitions in Xe XI [6]. These lines have recently been identified by Churilov et al. [7] by comparison of new very high resolution data with atomic structure calculations using the suite of codes developed by Cowan [8]. Considerable work has been expended on exploring the feasibility of using laser produced plasmas of xenon clusters produced by supersonic jets or gas puffs from nozzles or solid xenon targets [9]. The highest conversion efficiencies (1.2% into 2% bandwidth) have been achieved using solid xenon by Shields et al. [1...

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“…The radiative transitions rates in FAC are calculated in the single multipole approximation, and in this work they were obtained in the electric dipole approach. The UTA [15] formalism is used for the bound-bound transitions, so the transition energies include the UTA shift and the UTA width for each transition is provided. Furthermore, the line strengths are corrected due to the configuration interaction within the same non-relativistic configurations.…”

Section: Theoretical Modelmentioning

confidence: 99%

Determination and Analysis of the Thermodynamic Regimes of Xenon Plasmas

Rodríguez¹,

Gil²,

Florido³

et al. 2011

Contrib. Plasma Phys.

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Xenon is a common element employed, for example, as impurity in magnetically confined plasmas or the medium in which radiative shocks propagate in laboratory astrophysics. In both situations, it is required the knowledge of plasma parameters such as the average ionization, the charge state distribution, the atomic level populations and the radiative properties. In most cases, the plasmas are under non-local thermodynamic equilibrium (NLTE) conditions and these quantities should be determined by means of the so-called collisionalradiative models. For a high Z element like xenon this is a complex task and entails a high computational cost since it is necessary to solve a very large set of rate equations. In this work are characterized the thermodynamic regimes of xenon plasmas as a function of the matter density and temperature. This fact will allow us to establish in which regions of density and temperature the assumption of local thermodynamic equilibrium (LTE) is accurate and also in which regions it can be retained to estimate some plasma parameters but not others. Moreover, it is also provided information about the average ionization in a wide range of plasma conditions which covers both LTE and NLTE regimes which is valuable information in order to optimize subsequent calculations. Finally, it is also performed an analysis of the differences of NLTE and LTE simulations on several relevant plasma parameters. With this purpose, a comparison is made between the results of the calculation using detailed NLTE modeling with simulations that use the same energy level structure, but atomic populations that are forced into LTE.

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Quenching of transition arrays through configuration mixing

Cited by 86 publications

References 14 publications

Hybrid atomic models for spectroscopic plasma diagnostics

Hybrid atomic models for spectroscopic plasma diagnostics

UTA versus line emission for EUVL: studies on xenon emission at the NIST EBIT

Determination and Analysis of the Thermodynamic Regimes of Xenon Plasmas

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