Spectroscopic signatures of avoided crossings caused by charge exchange in plasmas

Oks, Eugene; Leboucher-Dalimier, E.

doi:10.1088/0953-4075/33/18/326

Cited by 14 publications

(23 citation statements)

References 15 publications

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“…This weak density dependence is a characteristic feature of the charge-exchange-caused dips (x-dips) -in distinction to the Langmuir-waves-caused dips whose positions scale as n 1/2 e . The found positions of the dips (3.1 ± 0.1 mÅ and 6.7 ± 0.2 mÅ from the density-shifted line centers) agree well with the theoretical positions of x-dips due to CE between C 6+ and Al 12+ ions [4]. Physically, the x-dips correspond to anti-crossings of terms of the one-electron quasi-molecule of nuclear charges Z 1 and Z 2 : anti-crossings enhance CE.…”

Section: Theoretical Analysis and Discussion Of Experimental Resultssupporting

confidence: 86%

X-ray spectroscopic study of charge exchange phenomena in plasma-wall interaction

Renner

Krouský

Šmíd

et al. 2013

EPJ Web of Conferences

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Abstract. Jets of energetic ions launched at laser-burnt-through foils represent an efficient tool for investigation of plasma interaction with solid surfaces (plasma-wall interaction, PWI) and for description of transient phenomena occurring close to the walls. Highly charged ions approaching the secondary target interpenetrate the near surface layer, collide with the counter-propagating matter and capture a large number of electrons. This results in a creation of atoms in highly excited Rydberg states or hollow ions with multiple inner vacancies; plasma jet and target ions may also undergo charge exchange (CE) processes. We report PWI experiments with Al/Si(PMMA) and Al/C targets irradiated at normal or oblique laser incidence. The distinct dip structures observed in red wings of Al Ly self-emission is interpreted in terms of CE between C 6+ and Al 12+ in the near-wall zone. The spectroscopic identification of CE phenomena is supported by results of analytical and numerical calculations.

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Section: Theoretical Analysis and Discussion Of Experimental Resultssupporting

confidence: 86%

X-ray spectroscopic study of charge exchange phenomena in plasma-wall interaction

Renner

Krouský

Šmíd

et al. 2013

EPJ Web of Conferences

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“…A quasi crossing of the TCC terms, by enhancing charge exchange, can result in unusual structures (dips) in the spectral line profile emitted by a Z-ion from a plasma consisting of both Z-and Z′-ions, as was shown theoretically and experimentally [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 73%

Electric field induced crossings of energy terms of a Rydberg quasi molecule enhancing charge exchange and ionization

Kryukov

Oks

2012

Can. J. Phys.

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Charge exchange is one of the most important atomic processes in plasmas. Charge exchange and crossings of corresponding energy levels that enhance charge exchange are strongly connected with problems of energy losses and of diagnostics in high temperature plasmas. Charge exchange was also proposed as an effective mechanism for population inversion in the soft X-ray and vacuum ultraviolet ranges. One of the most fundamental theoretical domains for studying charge exchange is the problem of electron terms in the field of two stationary Coulomb centers (TCC) of charges Z and Z′ separated by a distance R. It presents an intriguing atomic physics: the terms can have crossings and quasi crossings. These intrinsic features of the TCC problem also manifest in different areas of physics, such as plasma spectroscopy: a quasi crossing of the TCC terms, by enhancing charge exchange, can result in an unusual structure (a dip) in the spectral line profile emitted by a Z-ion from a plasma consisting of both Z-and Z′-ions, as was shown theoretically and experimentally. Before the year 2000, the paradigm was that the preceding sophisticated features of the TCC problem and its flourishing applications were inherently quantum phenomena. In 2000, a purely classical description of the crossings of energy terms was presented. In the present paper we study the effect of an electric field (along the internuclear axis) on circular Rydberg states of the TCC system. We provide analytical results for strong fields, as well as numerical results for moderate fields. We show that the electric field has several effects. First, it leads to the appearance of an extra energy term: the fourth classical energy term -in addition to the three classical energy terms at zero field. Second, but more importantly, the electric field creates additional crossings of these energy terms. We show that some of these crossings significantly enhance charge exchange, while other crossings enhance the ionization of the Rydberg quasi molecule. PACS Nos: 32.60.+i, 32.80.Ee, 34.70.+e, 33.80.Be, 31.15.-pRésumé : L'échange de charge est le plus important mécanisme atomique dans les plasmas. L'échange de charge et le croisement des niveaux d'énergie correspondants qui augmente l'échange de charge sont fortement connectés aux problèmes de perte d'énergie et de diagnostique dans les plasmas de haute température. L'échange de charge a aussi été proposé comme un mécanisme efficace pour l'inversion de population dans les domaines VUV et rayon-X mou. Le problème des termes de l'électron dans le champ de deux centres coulombiens stationnaires (TCC) de charges Z et Z′ séparés par une distance R, est central dans l'étude de l'échange de charge. C'est un problème intriguant en physique atomique : les termes peuvent avoir des croisements et des quasi croisements. Ces caractéristiques intrinsèques se manifestent également dans d'autres domaines de la physique, comme la spectroscopie du plasma : un quasi croisement des termes TCC, par augmentation de l'échange de charge, peut donner ...

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“…For this purpose, the relationship between Θ 0 and Θ d turns out to be determining (see Figure 5, where all possible cases are summarized). As one can see from (12), one of the two adiabatic dipole transition moment has a root at Θ = Θ d and another has a maximum if the upper limiting value Θ (x → −∞) = π/2−Θ 0 ≥ Θ d (regions III and IV on Figure 5). But there are no roots in the opposite case (regions I and II).…”

Section: The Roots Of the Dipole Moments And The Spectralmentioning

confidence: 99%

“…A representative example of this case is Al +12 (n = 4) + C +6 collisions that have been studied in experiments on hot dense plasmas produced by laser pulses [10][11][12][13][14]40]. Despite the energy splitting at large distances, two states still exist with asymptotically allowed and forbidden transitions.…”

Section: Charge-exchange In Excited States With Small Energymentioning

confidence: 99%

“…In spite of successful applications of the elaborated theory to experiments with neutrals, for example, [6][7][8][9], attention had not been paid to ion collisions in plasma, until recent experiments in hot dense plasmas [10][11][12][13][14] exhibiting fine structures, that is, satellites in F Lyman β profile emitted by a fluorine plasma, dips, and bumps in the Al Lyman γ profile emitted by a heterogeneous Al-C plasma. The fine structures in Al Lyman γ have been connected to intersections of QM Al-C energy terms.…”

Section: Introduction: Features Of Spectral Profiles Following the Inmentioning

confidence: 99%

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Optical Transitions and Charge-Exchange in Highly Charged Quasi-Molecules

Devdariani

Dalimier

Sauvan

2010

International Journal of Spectroscopy

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The interaction between quasimolecular states produces not only nonadiabatic transitions but also some exotic features in the wings of the spectral profiles emitted by the ions in collision. Although this concept has been fruitfully used for neutral species, some new highlighted experimental data on quasimolecular optical transitions in hot dense plasma have renewed the interest to the concept in the recent years. The present review deals with highly charged quasimolecules and it is dedicated specifically to quasimolecules formed by two bare nuclei and one bound electron. The reason for this choice is that, for such quasimolecules, the energy terms and the dipole moments of the optical transitions can be obtained straightforwardly in nonrelativistic case without any approximation that are typical for neutrals. Although the results obtained in the frame of the approach developed here are directly applicable to the case of single collisions or to low-density plasmas, they form a reasonable initial approximation for the problem of optical profiles in hot dense plasmas and can be regarded as a safe framework for qualitative discussions of profiles in those environments.

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Spectroscopic signatures of avoided crossings caused by charge exchange in plasmas

Cited by 14 publications

References 15 publications

X-ray spectroscopic study of charge exchange phenomena in plasma-wall interaction

X-ray spectroscopic study of charge exchange phenomena in plasma-wall interaction

Electric field induced crossings of energy terms of a Rydberg quasi molecule enhancing charge exchange and ionization

Optical Transitions and Charge-Exchange in Highly Charged Quasi-Molecules

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