Experimental determination of rate coefficients of charge exchange from<i>x</i>-dips in laser-produced plasmas

Dalimier, E.; Oks, Eugene; Renner, O.; Schott, René

doi:10.1088/0953-4075/40/5/007

Cited by 14 publications

(16 citation statements)

References 13 publications

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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: 74%

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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Section: Introductionmentioning

confidence: 74%

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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“…In the case under discussion, it leads to a connection between the spectral features and the cross sections of charge exchange in excited states. As an example inspired by the experiments [40], Figure 9 depicts the results of the closecoupled calculations of charge-exchange cross-sections in collisions Al +12 (n = 4) + C +6 → Al +13 + C +5 (n = 2) [42]. As one can see for this reaction, the only 5gσ − 6hσ channel accounts for charge exchange.…”

Section: Charge-exchange In Excited States With Small Energymentioning

confidence: 97%

“…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%

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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“…We present here a summary of theoretical results from [10][11][12][13][14][15]. The X-dips are caused by CE at quasi-crossings of the energy terms E(R) of the quasi-molecule Z-e-Z', made up of a H-like radiating ion Z and a perturbing fully stripped ion Z'.…”

Section: Theory Of X-dipsmentioning

confidence: 99%

Review of Langmuir-Wave-Caused Dips and Charge-Exchange-Caused Dips in Spectral Lines from Plasmas and their Applications

Dalimier

Oks

Renner

2014

Atoms

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We review studies of two kinds of dips in spectral line profiles emitted by plasmas-dips that have been predicted theoretically and observed experimentally: Langmuir-wave-caused dips (L-dips) and charge-exchange-caused dips (X-dips). There is a principal difference with respect to positions of L-dips and X-dips relative to the unperturbed wavelength of a spectral line: positions of L-dips scale with the electron density N e roughly as N e 1/2 , while positions of X-dips are almost independent of N e (the dependence is much weaker than for L-dips). L-dips and X-dips phenomena are important, both fundamentally and practically. The fundamental importance is due to a rich physics behind each of these phenomena. L-dips are a multi-frequency resonance phenomenon caused by a singlefrequency (monochromatic) electric field. X-dips are due to charge exchange at anticrossings of terms of a diatomic quasi-molecule, whose nuclei have different charges. As for important practical applications, they are as follows: observations of L-dips constitute a very accurate method to measure the electron density in plasmas-a method that does not require knowledge of the electron temperature. L-dips also allow measuring the amplitude of the electric field of Langmuir waves-the only spectroscopic method available for this purpose. Observations of X-dips provide an opportunity to determine rate coefficient of charge exchange between multi-charged ions. This is an important reference data, virtually inaccessible by other experimental methods. The rate coefficients of charge

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Experimental determination of rate coefficients of charge exchange fromx-dips in laser-produced plasmas

Cited by 14 publications

References 13 publications

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

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

Review of Langmuir-Wave-Caused Dips and Charge-Exchange-Caused Dips in Spectral Lines from Plasmas and their Applications

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