Absolute energies of the autoionization states ls2s22p" [LSJl with n = 0-2, ls2s2p" [LSJl with n = 1-3 and ls2p" [LSJl with n = 2-4 and nonautoionizing states ls22s22p" [LSJl with n = 0-1, ls22s2p" [LSg with n = 0-2 and ls'2p" [LSJl with n = 1-3 were calculated for ions with nuclear charge Z = 6-54 by using the 1/Z perturbation theory method.Relativistic corrections were taken into account in the frame of the Breit operators. The autoionization rates for the above-mentioned autoionization states for ions with Z = 6-54 were computed as well. These data are very important for modelling the satellite spectra produced by hightemperature plasma with thermal and non-thermal electrons.

This paper presents a detailed investigation of the temporal, spatial, and spectroscopic properties of L-shell radiation from 0.8 to 1.0 MA Mo x pinches. Time-resolved measurements of x-ray radiation and both time-gated and time-integrated spectra and pinhole images are presented and analyzed. High-current x pinches are found to have complex spatial and temporal structures. A collisional-radiative kinetic model has been developed and used to interpret L-shell Mo spectra. The model includes the ground state of every ionization stage of Mo and detailed structure for the O-, F-, Ne-, Na-, and Mg-like ionization stages. Hot electron beams generated by current-carrying electrons in the x pinch are modeled by a non-Maxwellian electron distribution function and have significant influence on L-shell spectra. The results of 20 Mo x-pinch shots with wire diameters from 24 to 62 microm have been modeled. Overall, the modeled spectra fit the experimental spectra well and indicate for time-integrated spectra electron densities between 2 x 10(21) and 2 x 10(22) cm(-3), electron temperatures between 700 and 850 eV, and hot electron fractions between 3% and 7%. Time-gated spectra exhibit wide variations in temperature and density of plasma hot spots during the same discharge.

We have studied the polarization properties of dielectronic satellite lines in Be-like Fe ions excited through resonant electron capture by an electron beam. Using the photon density-matrix formalism, we have calculated the degree of polarization and polarization-dependent spectra of dielectronic satellite lines, i.e., the spectral intensity distribution of lines associated with a given polarization state. Theoretical results have been compared with experiments performed at the Lawrence Livermore National Laboratory electron-beam ion trap where dielectronic satellite line emission from Fe ions produced at different energies of the electron beam was simultaneously recorded with two crystal spectrometers. These spectrometers had different polarization sensitivities. The experimental spectra recorded by the two spectrometers are reproduced by the theory. This ability to model the polarization dependence of x-ray line spectra is important for the diagnosis of electron beams in plasmas.

Spectra with spectral resolution λ/Δλ ≃ 3000-7000 in the vicinity of the He-like ion resonance lines Mg, Al, Si, P, S were obtained in CO2 laser-produced plasma. The wavelengths of these satellites were measured and compared with numerical calculations. Identification of lines or a group of overlapping lines was performed. Twenty-two transitions of dielectronic satellites for Be-like ions, 41 transitions for B-like, 40 transitions for C-like, 22 transitions for N-like, 12 transitions for O-like ions and 2 transitions for F-like ions were identified. The average between theoretical and experimental wavelengths was ±(0.0005-0.001)Å, but in some cases it was ±(0.002-0.003)Å.

A relativistic many-body method is developed to calculate energy and transition rates for multipole transitions in many-electron ions. This method is based on relativistic many-body perturbation theory (RMBPT), agrees with MCDF calculations in lowest order, includes all second-order correlation corrections, and includes corrections from negative-energy states. Reduced matrix elements, oscillator strengths, and transition rates are calculated for electric-dipole (E1) and electric-quadrupole (E2) transitions, and magneticdipole (M1) and magnetic-quadrupole (M2) transitions in Ni-like ions with nuclear charges ranging from Z = 30 to 100. The calculations start from a 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 Dirac-Fock potential. First-order perturbation theory is used to obtain intermediate-coupling coefficients, and second-order RMBPT is used to determine the matrix elements. The contributions from negative-energy states are included in the second-order E1, M1, E2, and M2 matrix elements. The resulting transition energies and transition rates are compared with experimental values and with results from other recent calculations.Résumé : Nous développons une méthode relativiste à N corps pour calculer l'énergie et les taux de transitions multiples dans les atomes multi-électroniques. Cette méthode, qui est basée sur la théorie perturbative relativiste (RMBPT), est en accord avec les calculs MCDF à l'ordre le plus bas, inclut toutes les corrections de corrélation du second ordre et les corrections pour les états d'énergie négative. Nous calculons les éléments de matrice réduits, les forces d'oscillateur et les taux de transition pour les transitions dipolaires électriques (E1), dipolaires magnétiques (M1), quadripolaires électriques (E2) et quadripolaires magnétiques (M2) dans les ions de type Ni avec charges nucléaires dans le domaine Z = 30-100. Le calcul démarre avec un potentiel Dirac-Fock 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 . Nous utilisons les perturbation au premier ordre pour obtenir les coefficients de couplage intermédiaire et au deuxième ordre RMBPT pour obtenir les éléments de matrice. Les contributions des états d'énergie négative sont inclues dans les éléments de matrice E1, M1, E2 et M2. Nous comparons nos énergies et taux de transition avec les résultats expérimentaux et avec les résultats calculés par d'autre sauteurs.[Traduit par la Rédaction]

No abstract

An analysis of the energy, spatial character, and temporal evolution of electron beams and hard x rays from 0.9 to 1.0 MA high-Z X pinches is presented. Experimental results from Ti, Fe, Mo, and W X pinches show that X pinches are an effective source of hard x rays with energies greater than 30 keV. Electron beams with energies up to 2 MeV higher than the applied anode-cathode voltage are generated along the pinch axis before the maximum current is reached. The beams have diameters of about 3 mm and generate bursts of hard x rays with sizes between 1 and 2 mm and total time durations of up to 150 ns. The measured 100-500 keV x-ray distribution is spectrally anisotropic. Hard x-ray synchrotron radiation in the side-on direction is proposed as a possible explanation of this anisotropy.

This paper presents the results of a broad investigation into the effects of the electron energy distribution function on the predictions of nonlocal thermodynamic equilibrium collisional-radiative atomic kinetics models. The effects of non-Maxwellian and suprathermal ("hot") electron distributions on collisional rates (including three-body recombination) are studied. It is shown that most collisional rates are fairly insensitive to the functional form and the characteristic (central or average) energy of the electron distribution function as long as the characteristic energy is larger than the threshold energy for the collisional process. Collisional excitation and ionization rates are, however, highly sensitive to the number of hot electrons. This permits the development of robust spectroscopic diagnostics that can be used to characterize the electron density, bulk electron temperature, and hot electron fraction of plasmas with nonequilibrium electron distribution functions. Hot electrons are shown to increase and spread out plasma charge state distributions, amplify the intensities of emission lines fed by direct collisional excitation and radiative cascades, and alter the structure of satellite features in both K - and L -shell spectra. The characteristic energy, functional form, and spatial properties of hot electron distributions in plasmas are open to characterization through their effects on high-energy continuum and line emission and on the polarization of spectral lines.