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Influence of multiple outer-shell electron stripping on the Kα and Kβ x-ray energies of iridium

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Physica Scripta
Authors:
J. Rzadkiewicz at National Centre for Nuclear Research
J. Rzadkiewicz
Katarzyna Słabkowska at Nicolaus Copernicus University
Katarzyna Słabkowska
Marek Polasik at Nicolaus Copernicus University
Marek Polasik
Joanna Starosta-Sztuczka
Joanna Starosta-Sztuczka
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We present theoretical predictions for iridium K alpha(1,2), K beta(1,3) and K beta(2) energy shifts as a function of outer-shell stripping, evaluated using the multiconfiguration Dirac-Fock method including Breit interaction and QED corrections. The energy shifts are consistent with the K-lines emitted by the plasma made in the plasma-filled rod pinch, and potentially relevant to diagnostics of high-energy density laser-produced plasmas as studied in connection with the National Ignition Facility.
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... Almost all the inner-shell vacancies give rise to various characteristic lines, and these would show the ionization energy shift of interest here. Energy shifts for Kα 1 (solid) and Kα 2 (dashed) lines (as a function of outer-shell stripping of iridium) predicted by MCDF calculations (presented already in [3]). The squares and their size indicate the measurement [1] and the estimated error. ...
... The first one [1] measured a ∼+10 eV increase in the ∼60 keV photon energy of the Kα 2 line of iridium. This energy shift turned out to be consistent with subsequent atomic physics computations, and with the ionization predicted from a simple model for this particular plasma [1][2][3]. More extensive computations of the ionization energy shift to the L x-ray lines of tungsten were essential for analysis in another paper [4]. ...
... These computations of the ionization-energy shift were specific to the experiments. The more systematic program of computations, results of which are presented in this and earlier papers [3,[5][6][7], intends to clarify when the ionization energy shift might become useful in plasma diagnostics. ...
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Ionization can affect the energy of characteristic x-ray lines sufficiently for a single line to be of value in plasma diagnostics. Recently, the ionization of a hot, dense tungsten plasma was determined from a detailed analysis of a single, highly resolved L x-ray line, and in an iridium plasma the change in energy of a single K x-ray line confirmed the theoretical estimate of the ionization. Diagnosing plasmas by these ionization energy shifts depends essentially on computations that can now be performed with sufficient accuracy, e. g. with the multi-configuration Dirac-Fock method. Besides extending earlier computations on the influence of outer-shell ionization on the energy of tungsten's K and L x-ray lines, this paper also presents the effect of ionization on the lower-energy M x-ray lines and a discussion of their relative merits for plasma diagnostics.
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... The third case study is focused on core radiative transitions in stripped tungsten. The energy shifts of Kα 1,2 , Kβ 1,3 and Kβ 2 lines of stripped high-Z atoms were suggested to be potentially relevant to diagnostics of high-energy density laser-produced plasmas [48]. Hence, the Kα 1 (1s −1 → 2p −1 3/2 ) and Kα 2 (1s −1 → 2p −1 1/2 ) transitions in W 7+ were selected as a second case study. ...
... For Kα 1 and Kα 2 transitions in W 7+ , Fac calculated numbers are smaller by about 10 eV than those obtained by MCDHF codes. This difference is too large to estimate outer-shell ionization level properly [48]. One can conclude that Fac code is accurate enough in the cases when radiative transitions are linked to electron jump around valence shells (if not very big accuracy is required), but is not accurate enough if transitions are linked to inner-shell hole states. ...
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... Part of our previous theoretical results has been already used in order to obtain the information about some of the plasma parameters. The value of energy shift for strong K 2 line of iridium registered using fi lter (i.e., K-edge fi lter) for iridium plasma generated by the Naval Research Laboratory's (NRL) Gamble II pulsed power machine, using plasma--fi lled rod pinch (PFRP) diode allowed the precise determination of ionization level for iridium (q ~ 17) and the electron temperature of iridium plasma (~60 keV) [4,5,9]. Recently [7], on the basis of our theoretical studies has been shown the reliable Diagnostics of the plasma parameters based on the K X-ray line positions for various 4d and 4f metals interpretation of not explained earlier the mystery of ytterbium's K line (the negative ionization energy shift of this line) emitted from the plasma produced also by the PFRP diode. ...
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Radiative double-electron capture by fully stripped and one-electron ions in gas and thin-foil targets
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Ultra-high electron beam power and energy densities using a plasma-filled rod-pinch diode
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Relativistic atomic structure theory: Some recent work
Article
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