Population inversion of Al<sub>xi</sub>in a laser plasma

Kononov, É. Ya.; Koshelev, K. N.; Levykin, Yu A; Sidelnikov, Yu. V.; Churilov, S S

doi:10.1070/qe1976v006n03abeh011002

Cited by 35 publications

(9 citation statements)

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“…Experimental results on satellite spectra to the resonance lines of H-like and He-like ions have been reported for practically all high-temperature laboratory plasmas: 0-pinch (Li-like emission of N, O, F and Ne) [295-297], plasma focus (Li-like emission of Ne and Ar) [298,299], tokamak (mainly Fe spectra) [51, [300][301][302], exploding wire (Al, Si, and Fe spectra) [303,304], Z-pinch (Ar spectra) [305], beam foil (Si spectra) [306,307], high-vacuum spark (mostly Fe spectra, but also several spectra for elements from Ti up to Mo) [253,[308][309][310][311][312][313][314][315][316][317][318][319][320], and laser-produced plasmas (elements from B up to Fe) [5,199,212,231,249,289,290,292,[321][322][323][324][325][326][327][328][329][330][331][332][333][334]. Some of this work was also concerned with the Kg spectrum, i.e.…”

Section: Fig41 Theoretical Relative Intensities Of the Satellites Of ...mentioning

confidence: 99%

“…The ionization temperature T z has been evaluated from inner-shell excitation satellites in laser-produced plasmas [5,199,289,290], vacuum sparks [315], and exploding wires [303]; Boiko et al [5] have discussed in detail how to proceed in order to subtract the contribution due to dielectronic capture. In all these highdensity plasmas, one finds T z < T e .…”

Section: Photon Countsmentioning

confidence: 99%

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Soft-X-ray spectroscopic diagnostics of laboratory plasmas

1981

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Soft X-ray spectroscopic diagnostics of laboratory plasmas are considered. To start with, the state of the art in the knowledge of rate coefficients, cross-sections, transition probabilities, and ionization equilibrium calculations is reviewed. Next, the plasma spectral emission, i.e. continuum and line emission (including satellites), line broadening (including opacity), and total emitted radiation as an energy loss process, is considered. To conclude, a short discussion of X-ray plasma sources and instrumental problems is presented.

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Section: Fig41 Theoretical Relative Intensities Of the Satellites Of ...mentioning

confidence: 99%

Section: Photon Countsmentioning

confidence: 99%

Soft-X-ray spectroscopic diagnostics of laboratory plasmas

1981

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“…For transitions in the x.u.v. region this requires expansion times of order 100 ps, a value characteristic of the expansion of plasma formed from small targets by laser irradiation, and indeed observations have been made of inversions generated in such expansions (Irons & Peacock 1974;Key 1979;Kononov et 1976;Bhagavatula & Yaakobi 1978). If, however, this approach is to be used to generate sufficient gain for laser action, the target must be appropriately chosen to allow the inversion to be generated rapidly at a high density, and therefore large gain.…”

Section: R Ecombination Lasermentioning

confidence: 99%

Extreme ultraviolet laser action in plasmas

Pert

1981

Phil. Trans. R. Soc. Lond. A

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The development of a laser operating in the extreme ultraviolet or X-ray spectral regions remains an outstanding problem of current technology. Despite the many proposals, no demonstration of significant gain on a transition in this region has yet been reported. The constraints introduced by decreasing wavelength are increasingly severe, demanding high pump power in a system with a relatively short lifetime. In consequence, much attention has been paid to the use of plasma, often generated by high power laser irradiation, as the gain medium. In this paper I briefly outline the various avenues by which laser action in plasmas has been explored, with a view to identifying those which seem at present to offer promise of success. Particular attention is given to the recombination scheme with an emphasis on a recent demonstration of gain.

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“…Kononov et al, 1977) Te increases in a jump and then remains constant (Figure 1, al). The fractional ion abundances approach their steady-state distribution (bl).…”

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A possible explanation of non-steady-state appearances in X-ray spectra of solar flares

Koshelev

Kononov

1982

Sol Phys

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A model of essentially transient ionization of plasma is suggested to explain some features in observed spectra of solar flares, which cannot be understood if stationary conditions are assumed.In the recent papers of Doschek et al. (1979), Feldman et al. (1980), and Doschek et al. (1980 newly observed high-resolution X-ray spectra of solar flares were reported. It was pointed out that relative intensities of the resonance lines and satellites belonging to the He-like and H-like iron and calcium ions showed a non-steady-state character of ionization distribution in terms of an ionization temperature Tz and an electron temperature Te as introduced by Gabriel (1972). Te is determined from the intensity ratio of a dielectronic satellite (DS) to the resonance line (RL) of a particular ionization stage, and Tz is derived from the intensity ratio of an inner-shell excited satellite (IS) to RL and/or RL(Z) to RL(Z + 1) ratio of two subsequent ionization stages. Two essential points could not be explained satisfactorily in the spectra mentioned: (i) The spectra look like as if they originated from 'underionized' plasma (transient ionizing coriditions, Tz < Te) during the whole time history of a flare including the decay phase; (ii) the value of T, derived from the DS/RL ratio for the H-like ions Ca xx (the ionization energy IP = 5.3 keV) appears to be higher than that for the He-like ions Fe xxv with higher IP = 8.5 keV. E.g., at 18h09m24 ~ UT Te(Ca xx) = 30 • 106 K and Te(Fe xxv) = 22 • 106 K (see Table 1 in Doschek et al., 1979).The underionized conditions are observed also in most of laboratory plasma sources: vacuum sparks, laser-produced plasmas, tokamaks (see e.g. Kononov, 1978, Bitter et al., 1979. This effect may be of 'computational' origin: Atomic constants of highly ionized atoms which are used in interpretations of spectra could be calculated with some uncertainties. Until now, however, all the theoretical methods give rather consistent values for cross-sections and atomic transition probabilities, which always confirm the T~ > Tz trend (Bhalla et al., 1975;Vainstein et al., 1980). Moreover, in all the observations of very highly ionized atoms spectra, such as Fe xxv-xxvI, one can see that the product of the electron density Ne and the life-time of plasma r is comparable to the reCiprocal of the ionization rate of relevant ions. Hence, the transient character of ionization should be taken into account. The transient ionization approach is known to be applied to solar flares (see e.g. Mewe and Schrijver, 1980;Shapiro and Moore, 1977). Alternative attempts to bring Te and T~ into the ionization equilibrium consistency were made by Doschek et al. (1981). They account for higher level contributions to the Solar Physics 77 (1982) 177-181. 0038-0938/82/0771-0177 $00.75. Copyright 0 1982 by D. Reidel Publishing Co.,

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Population inversion of Al_xiin a laser plasma

Cited by 35 publications

References 0 publications

Soft-X-ray spectroscopic diagnostics of laboratory plasmas

Soft-X-ray spectroscopic diagnostics of laboratory plasmas

Extreme ultraviolet laser action in plasmas

A possible explanation of non-steady-state appearances in X-ray spectra of solar flares

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Population inversion of Alxiin a laser plasma

Cited by 35 publications

References 0 publications

Soft-X-ray spectroscopic diagnostics of laboratory plasmas

Soft-X-ray spectroscopic diagnostics of laboratory plasmas

Extreme ultraviolet laser action in plasmas

A possible explanation of non-steady-state appearances in X-ray spectra of solar flares

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Population inversion of Al_xiin a laser plasma