Quantentheorie und Astronomie

Unsöld, Albrecht

doi:10.1002/phbl.19480040502

Cited by 9 publications

(27 citation statements)

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“…The effect of the surrounding ions on the statistical weights of the bound states has been, since Unsöld's pioneering work [26], analyzed, most notably, by Gündel [13,14] and by Hummer and Mihalas [18]. The latter work also provides a detailed and comprehensive review of the progress in the field by the year 1988.…”

Section: Comparison With Results Found In Literaturementioning

confidence: 99%

“…As it was already said, a change in the nature of an electron state, from being a bound state of a single ion in dilute plasmas to encompassing several ions in dense plasmas, is closely related to the possibility of the escape of an optical electron out of the parent ion potential well [16,18,26,29]. The low-frequency component [18] of the microfield produced at the atom (ion) location by the surrounding charged particles can lower the atomic potential barrier sufficiently for an atomic electron either to tunnel out of its potential well or to escape above the peak of the lowered potential barrier.…”

Section: Basis Of the Present Approachmentioning

confidence: 99%

“…The low-frequency component [18] of the microfield produced at the atom (ion) location by the surrounding charged particles can lower the atomic potential barrier sufficiently for an atomic electron either to tunnel out of its potential well or to escape above the peak of the lowered potential barrier. The two approximations most commonly used to describe the escape of the optical electron from its parent ion in plasmas are the Uniform Local Microfield (ULM) approximation and the Nearest Neighbor approximation, both dating back to the original Unsöld paper [26]. The difference between the two approximations is in the assumed spatial dependence of the field acting on an atom.…”

Section: Basis Of the Present Approachmentioning

confidence: 99%

“…If q is above the barrier, then the optical electron will have comparable probabilities to be close to the neighbor ion or close to the parent ion, therefore, the state q is collectivized. The identification of the above-barrier states as collectivized (i.e., no longer bound to a single ion) is wellestablished [13,18,26,29]. Still, we will further discuss this definition in order to consider possible caveats.…”

Section: Collectivization Of Atomic (Ionic) Statesmentioning

confidence: 99%

“…Note that these considerations have led us to the expression obtained by Unsöld in his well-known "perturbing ion" model [26]. It is noteworthy that in the limit Z i Z 0 the external field becomes nearly uniform, and the result approaches the uniform-field estimate (7).…”

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confidence: 99%

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Effective statistical weights of bound states in plasmas

Fisher

Maron

2002

The European Physical Journal D - Atomic, Molecular and Optical

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Abstract. Based on recent advances in the study of the statistics of interparticle distances and angles in plasmas, we develop an approach for the determination of the effective statistical weights of atomic (ionic) quantum states in ideal and nonideal plasmas. This approach allows one to account naturally for the effects of both the perturbation of the bound states by the neighboring ions and for the binding energy reduction due to the screening of the Coulomb interaction. We analyze the roles of tunneling and overbarrier escape of the optical electron from the parent ion potential well. The effects of neighbor ions and free electrons on these processes, and the simultaneous presence of several perturber ion species in the plasma are treated. We show that the present approach offers significantly more accurate effective-statistical-weight values in comparison to the existing theoretical treatments, and yields physical expressions for the empirical factors of the existing theories. Examples of calculations of effective statistical weights are given. The effects of the atomic (ionic) states collectivization on the collisional-radiative kinetics of dense plasmas are discussed.

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Section: Comparison With Results Found In Literaturementioning

confidence: 99%

Section: Basis Of the Present Approachmentioning

confidence: 99%

Section: Basis Of the Present Approachmentioning

confidence: 99%

Section: Collectivization Of Atomic (Ionic) Statesmentioning

confidence: 99%

mentioning

confidence: 99%

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Effective statistical weights of bound states in plasmas

Fisher

Maron

2002

The European Physical Journal D - Atomic, Molecular and Optical

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Die kontinuierliche Emission von Argon bei hohen Drücken

Gall¹,

Riemann²

1970

Contrib Plasma Phys

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Eingrg;ingen nm 20. 0. Inti!) JIit einem Hochdruckkaskildenbogen wird der spektrale Einissionskoeffizient von ,\rgon in -4bhiCngigkeit von dem Driick (1, 4, 7 kind 12 at) iind der Ternperatiir esperinientell erniittelt nnd niit dern theoretisch bestininiten Emissionskoeffizienten verglichen. Fiir das Rekombinationskontinuurn ergiht sich eine unbefriedigende Ubereinstirnrnting von Theorie und Experiment. Xus dem Verhdtnis der Kontinuiirnsziir Linienintensititt werden ..\ussapen uber den Verlaiif der effektiven Ionisieriingsspanniingserniedrigiing flir das Kontinriuni geniacht. Die Korrektiirfaktoren f fiir dns Rekombinntionskontiniiiini, die die Xbweichruig des kLssisch-korrespondenzni~~ig voni quantenmechaniscli berechneten Eniiusionskoeffizienten nngeben. uerden fiir drei LVellenliingen experimentell best ininit.

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The Influence of Particles Interaction in Low‐Temperature Plasma on its Composition and Optical Properties

Sevast'yanenko

1985

Contrib Plasma Phys

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\ Ill(Jde1 theory of the influence of particles interaction in pliisrna on its composition and optical properties is developed.The interaction of charged particles in plasma reduces the ionization energy of atonis and ions. The action of internal microfields in plasma on atoms and ions reduces the statistical weight of electron levels which affects the populations of excited states. The latter effect lcads to a n cffectivc. cutoff of partition functions and determines the behaviour of optical properties of plasnia (of absurption coefficicnt and ernissivity) a t increased niimber dcnsities of charged particles.The formulas are obtained for enleulation of the continuous and discrete spectrum in plasma taking into account the particles interaction. A non-monotonic dependence of optical plasma density upon number density of charged particles is quantitatively explained. A satisfactory ngreciiient is obtained with a large number of experimental dnta some of which were considered to be contradictory.The method developed can be used for calculations in the field of atomic spectroscopy and low-temperature plasma physics including increased densities of charged particles. The use of the formulns obtained in plasma diagnostics will enable one to avoid considerable errors.Electron structure of atoms, intensities and half-widths of spectral lines, photoionization cross sections of bound states of isolated particles are known sufficiently well, however, the spectral absorption coefficient or emissivity calculated without taking into account particles interaction in plasma often are not in agreement with experiments. The discrepancy exceeds a factor of two or more a t increased densities. Until now there has been in the literature no adeqiiate theory satisfactorily describing the influence of the interaction on the properties of real atoms.Below a model theory is presented which enables one to take into account the tlistrrrbing influence of charged particles in plasma on its composition. thermophysical and, principally, optical properties. A careful comparison with arailable experimental data i. ; carried out. A satisfactory agreement reached there allows one to recommend tlic developed model for its use in practical computations and in plasma diagnostics. USSR, 1981, P a r t I, p. 339-340.(1966) 485.Recelved October 31, 1RP3

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Quantentheorie und Astronomie

Cited by 9 publications

References 0 publications

Effective statistical weights of bound states in plasmas

Effective statistical weights of bound states in plasmas

Die kontinuierliche Emission von Argon bei hohen Drücken

The Influence of Particles Interaction in Low‐Temperature Plasma on its Composition and Optical Properties

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