M. Cornille

Autoionization rates for 1s2s22p2, 1s2s2p3, 1s2p4 states of B-like ions (6 < Z < 54) for decay via different channels

Two different calculational methods, MZ and AUTOLSJ, are used to obtain autoionization rates for doubly excited states 1s2s22p2, 1s2s2p3, 1s2p4 of B-like ions in a wide range of nuclear charge Z (6 ≤ Z ≤ 54). Besides the total autoionization rates decayed via channels, so-called partial rates are computed in the intermediate coupling scheme. The Z-dependences of the partial rates are investigated in detail. A comparison shows a good agreement between these two methods. These data can be used to model dielectronic satellite spectra in plasmas. In particular, amplitudes and partial rates of autoionization decay are of importance for detailed atomic kinetic calculations and for the the study of polarization properties of dielectronic satellite spectra.

Energies and autoionization rates for Be-like systems. comparison of two methods: AUTOLSJ and MZ

Energy and autoionization rate for Be-like systems (1s2s22p, 1s2s2p2, 1s2p3) with Z = 6-42 have been calculated with two methods: AUTOLSJ (SUPERSTRUCTURE: including only the configurations of the complexes: 1s2s22p, 1s2p3 and 1s2s2p2) and (MZ) perturbation theory methods. Non-relativistic and relativistic parts of the energy have been considered separately. Relativistic effects have been taken into account by the Breit-Pauli operators. Non-relativistic and relativistic autoionization decay have been compared in the two methods, the contributions of 1s22s and 1s22p decay channels have been investigated.

X-ray line polarization spectroscopy of He-like Si satellite line spectra

Laser-produced plasmas driven by high-intensity, femtosecond-duration pulsed lasers have been recognized as sources of short-duration x-ray line emissions. Electron kinetics simulations of such transient and nonequilibrium plasmas predict non-Maxwellian electron distributions and even the presence of electron beams. X-ray line polarization spectroscopy is a diagnostic that can be used to study the directionality of the electron distribution function and thus test electron kinetics simulation results. To this end, we use a time-dependent, collisional-radiative atomic kinetics model of magnetic sublevels to understand the underlying processes and mechanisms leading to the formation of polarized x-ray line emission in Si plasmas driven by high-intensity, ultrashort duration pulsed lasers. We focus on the polarization properties of the He-like Si satellites of the Lyα line. In the cases under consideration, the relevant line emissions last less than 1 ps during which the plasma undergoes a rapid development. ...

Soft x-ray and Auger electron spectroscopy of single and double electron capture processes in slow Ne8++He collisions

We have performed high resolution extreme ultraviolet (EUV) photon and Auger electron measurements to elucidate single and double capture processes in Ne8++He single collisions at 80 keV impact energy. Numerous new transitions both in the Auger and the EU

Z-dependences of the energy levels and autoionization rates for 2141′ states of two electron systems

Abstract Three different calculational methods (AUTOLSJ, MZ, MCDF) are used to obtain energy levels and autoionization rates for doubly-excited states 2141′ of two electron systems (10⩽ Z ⩽42). By ordering all the states by energy within each block of a given angular momentum J and parity, it becomes possible to compare energy levels and autoionization rates obtained by the three methods. The Z dependences of the quantities are investigated for each calculational method for 10⩽ Z ⩽42. The final comparison reveals rather good agreement between the results obtained by the three methods.

Quantum-mechanical Calculations of Ne VII Spectral Line Widths

We present in this paper quantum‐mechanical calculations for the electron impact Stark linewidths of the 2s3s–2s3p transitions for the beryllium‐like neon. Calculations are made in the frame of the impact approximation and for intermediate coupling, taking into account fine structure effects. A comparison between our calculations and experimental and other theoretical results showed a good agreement. This is the first time that we find such a good agreement between quantum and experimental linewidths of highly charged ions.

Fe XXIII-Fe XIX theoretical spectra in two calculational methods

Two different calculational methods are compared for atomic data used to analyse transitions of the type 1s2sk2pn-1s22sk2pn-1. Wavelengths, radiative transitions, autoionisation probabilities and intensity factors are compared. These parameters are needed for diagnostics of low-density plasmas as found in solar flares and tokamak devices.

New modeling of germanium soft-X-ray lasers using extended atomic data

Abstract A collisional radiative model, explicitly including the interaction of the amplifying medium with the X-ray laser beam, is used to calculate the intensity of the 2–1 and 0–1 lines in neon-like germanium, as well as the population densities. The required energy levels and electron-impact collision strengths involve the configurations 1s22s22p6, 1s22s22p53l, and 1s22s2p63l (l=s,p,d). The fine-structure excitation rates coefficients are presented for temperatures in the range 100–700 eV. Well-known numerical codes are used for the atomic structure (SUPERSTRUCTURE) and electron–ion collisions (DISWAV/JAJOM). Finally, we solve the collisional radiative population equations. It is recommended to use excitation rates obtained from the extensive quantum calculations, rather than fit formulae. In this case, the calculated populations and intensities show substantial changes.

Model potential calculations and spectroscopic observations of some doubly excited states in beryllium-like Ne VII

Energy level positions and branching ratios for radiative decay have been calculated for a number of doubly excited states in beryllium-like Ne VII using the SUPERSTRUCTURE code. These are compared with weak unidentified features observed in spectra obtained from foil-excited neon beams at energies of 6, 13 and 18 MeV.

Theoretical analysis of solar corona spectra emitted in the 14--19 A wavelength range

The atomic data required to analyse low density coronal plasmas have been calculated and used to interpret some X‐ray spectra observed by the Flat Crystal Spectrometer of the SMM/NASA satellite in the 14–19 A wavelength range. The emission lines correspond mainly to Fe ions (Fe XVI, Fe XVII, Fe XVIII) and some O ions (O VII, O VIII).