Quasiclassical theory of dielectronic recombination in plasmas

We consider the effects of plasmas on dielectronic-recombination (DR) rates. Effects of plasmas electric fields on DR rates are analyzed in detail in the space of parabolic quantum numbers. A quasiclassical approach is used to obtain general analytical expressions for DR rates in the parabolic basis for arbitrary types of ions having transitions without change of core principal quantum numbers (Δn=0 transitions) responsible for the main contribution to DR rates. The approach makes it possible to investigate scaling laws for dependences of both total and differential DR rates on atomic parameters. Effects of electron collisions and ionization are taken into account with the help of cutoff procedures. Numerical data are presented for Li- and Na-like ions under typical plasma conditions. A comparison with numerical calculations for specific ions is presented

Coherent information analysis of quantum channels in simple quantum systems

The coherent information concept is used to analyze a variety of simple quantum systems. Coherent information was calculated for the information decay in a two-level atom in the presence of an external resonant field, for the information exchange between two coupled two-level atoms, and for the information transfer from a two-level atom to another atom and to a photon field. The coherent information is shown to be equal to zero for all full-measurement procedures, but it completely retains its original value for quantum duplication. Transmission of information from one open subsystem to another one in the entire closed system is analyzed to learn quantum information about the forbidden atomic transition via a dipole active transition of the same atom. It is argued that coherent information can be used effectively to quantify the information channels in physical systems where quantum coherence plays an important role.Comment: 24 pages, 7 figs; Final versiob after minor changes, title changed; to be published in Phys. Rev. A, September 200

Interaction of ultra-short electromagnetic pulses with ions in hot dense plasmas

International audienceThe general properties of ultra-short electromagnetic pulse (USP) interactions with highly charge ions in dense and high temperature plasmas are considered. The application of USP in X-ray spectral range provided by modern technology including free-electron laser machines opens up new opportunities for investigations of dense plasmas. They are based on the possibility of USP penetration into optically dense media due to their broad spectral distribution. In the framework of the use of USP for active spectroscopy in high energy density plasmas, new expressions of the transition probabilities are proposed. An aluminum plasma at local thermodynamic equilibrium is considered. The interaction of USP with hydrogen-like ions at N e =2⋅10 22 cm-3 and T=1 keV is analyzed in details by taking into account both the specificity of the USP and the plasma effects, such as Stark and Doppler effects on the line profile of the excited radiative transitions. The results are applied for demonstration of optical depth and pulse duration effects on excitation probabilities of the n=1 to n=3 radiative transition, which is the simplest atomic scheme to observe fluorescence signal

Excitation of hydrogen atom by ultrashort laser pulses in optically dense plasma

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Radiative Cascade Due to Dielectronic Recombination

The problem of a determination of two-dimensional (in quantum numbers n,l) atomic level populations under the action of dielectronic recombination (DR) sources and corresponding radiative cascades is considered. A quasiclassical approach is used for calculations both DR rates and radiative cascade transitions which makes it possible to obtain a simple analytical solution of the problem. The populations obtained are expressed in the anlytical form allowing estimations of energy level populations for every types of ions having transitions in their cores without change of principle quantum numbers. The results are illustrated by numerical data for energy level populations of Li-like ions

Free-bound electron exchange contribution to l-split atomic structure in dense plasmas

An analytical expression for the exchange energy between the bound electron in hydrogen-like ions and the free electrons of plasma is proposed. Two limiting cases are identified: 1) the low temperature limit where the energy depends linearly on density and on the ion charge as 1/Z2 but does not depend on the temperature itself, 2) the high temperature limit where the energy depends on temperature as 1/T but does not depend on the ion charge. These two regimes are separated by a characteristic temperature (T∗ = 4Z2Ry) which is a universal parameter depending only on the charge Z of the ions. We presented numerical results for aluminum: the exchange energy contributes about 15% to the total plasma energy and can reach an order of 10−4 of the total transition energy. Comparison to the Local-density Approximation (Kohn-Sham) exchange energy shows a good agreement