L-shell Emission Research Articles

Density and temperature sensitive features in high temperature plasma L-shell xenon emission spectra.

We present model calculations demonstrating new density and temperature sensitive ratios of groups of F- and Ne-like Xe lines which are suitable for diagnosing plasma conditions. The method is illustrated by using L-shell Xe emission to infer ${\mathit{T}}_{\mathit{e}}$ in the fuel region of indirectly driven plastic capsules filled with deuterium and doped with 0.1% Ar and 0.02% Xe. The technique uses tractable atomic models and appears scalable to other Ne-like ions.

ROSAT observations of cataclysmic variables: A search for the boundary layer emission

Many cataclysmic variables (CVs) and low-mass X-ray binaries show He II line emission at wavelength 1640 and wavelength 4686. As recombination lines of an ion requiring 55 eV for ionization, these lines cannot be attributed to gravitational heating in the disk but could be due to reprocessed 55-280 eV X-rays which may be produced in a boundary layer at the disk/star surface. We undertook a search for this soft component using the Positon Sensitve Proportional Counter (PSPC) on ROSAT. The photon fluxes we observe are not sufficient to produce the He II wavelength 1640 fluxes observed by IUE. If we assume that the X-ray luminosity is due to emission from a boundary layer, then the observed quiescent luminosity is one-quarter of the total accretion luminosity as determined by optical and ultraviolet observations rather than the one-half that is predicted by some theories. An additional very soft component (e.g. an approximately equal 10-20 eV blackbody) could provide sufficient photons in the 0.055-0.100 keV band to produce the observed He II fluxes and contribute the additional luminosity from the boundary layer while remaining hidden to the PSPC and IUE. Alternatively, the high He II line fluxes could be evidence for high-temperature collisionally ionized material. We also find evidence for line emission at approximately equal 0.9 keV consistent with L-shell emission from highly ionized iron.

Ar L-shell and metal M-shell Auger electron emission for 14 keV Ar + ion impact on Ca, Sc, Ti, V, Cr, Fe, Co, Ni, and Cu

Ar projectile L-shell and metal target M-shell Auger electron emission have been studied by 14 keV Ar + ion bombardment on Ca, Sc, Ti, V, Cr, Fe, Co, Ni, and Cu targets at an incidence angle of 60° with respect to the surface normal. We observe that the width of the Ar Auger peak progressively reduces and its total intensity decreases exponentially with increase of the target atomic number and that the metal M-shell autoionization peaks are completely absent.

A feasibility study of an XUV spectroscopic measurement of electron density and temperature fluctuations in tokamak plasma center (abstract)

With the advent of layered synthetic microstructure (LSM) technology, high-reflectivity narrow-band XUV filters, and LSM coated gratings become available, thus making possible normal-incidence high-throughput devices in the 10–200 Å range. Therefore it may become feasible to measure rapid (τ∼10−6 s) fluctuations of the electron density and temperature in the hot central region of the tokamak plasma, by measuring fluctuations on the L-shell charge-state line emissions. We present and discuss the linear dependence of correlated line intensity fluctuations on local T̃e and ñe. Various configurations for the proposed measurements are presented and evaluated.

Iron K-shell emission from NGC 1068

view Abstract Citations (60) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Iron K-Shell Emission from NGC 1068 Band, David L. ; Klein, Richard I. ; Castor, John I. ; Nash, J. K. Abstract We model the X-ray iron line emission from NGC 1068 observed by the Ginga satellite using the new multiline, multilevel, non-LTE radiative transport code ALTAIR and a detailed atomic model for Ne-like through stripped iron (Fe XVI-XXVII). Our calculations are based on the model of NGC 1068 proposed by Antonucci and Miller where the emissions from an obscured type 1 Seyfert engine are scattered into our line of sight by ionized gas. The X-rays passing through the ionized gas induce iron Kα line emission. The atomic model was constructed to describe in detail the K-shell ionization and Kα line emission, as well as to calculate the ionization state properly. We find a greater equivalent width than previously predicted because the observed Kα line is produced not only by fluorescence but also by line scattering of the continuum into our line of sight. Detailed radiative transfer can have a significant effect on the observed line flux both for the Kα line and for the L-shell emission. The degree of iron ionization increases with temperature; therefore the Kα equivalent width and energy are functions not only of the ionization parameter, but also of the column depth and temperature. For a likely model of NGC 1068 we find that the iron abundance is about twice solar, but that modifications of this model may permit a smaller abundance. Publication: The Astrophysical Journal Pub Date: October 1990 DOI: 10.1086/169245 Bibcode: 1990ApJ...362...90B Keywords: Emission Spectra; Extremely High Frequencies; Iron; Line Spectra; X Ray Spectra; Ionized Gases; Polarized Light; Radiative Transfer; Thermodynamic Equilibrium; Astrophysics; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 1068; GALAXIES: NUCLEI; GALAXIES: SEYFERT; RADIATION MECHANISMS; RADIATIVE TRANSFER; X-RAYS: SPECTRA full text sources ADS | data products SIMBAD (1) NED (1)

Experimental investigation of angular dependence of photon induced L-shell X-ray emission intensity

The angular dependence of emission intensity of L shell X-rays induced by 59.57 keV photons in Pb and U is investigated by measuring the normalized intensities of the resolved L X-ray peaks at different angles varying from 40° to 120°. It is observed that while L l and Lα X-ray peaks (originating fromJ = 3/2 state) show some anisotropic angular distribution, the emission of Lβ and Lγ X-ray peaks is isotropic. The present results contradict the calculations of Co-oper and Zare (1969) that after photoionization of inner shell, the vacancy state has equal population of magnetic substates and the subsequent X-ray emission is isotropic but confirm the predictions of Fluggeet al (1972) that the atomic inner shell vacancies produced after photoionization are aligned and the x-ray emission from the filling of vacancies in state withJ ⩾ 3/2 is anisotropic.

Proton-induced L-shell X-ray emission cross-sections of elements with 24 ≦Z2 ≦ 50 for projectile energies between 30 and 350 keV

Total L-X-ray emission cross sections are measured for proton bombardment of thin and thick targets in a wide range of elements. The results are compared with the PWBA-theory. The introduction of corrections with respect to the Coulomb deflection of the particles and to the change of the binding energy of the target electrons improves the agreement between the calculated and measured results. It is established within the experimental error that the parametrized cross section for constant reduced projectile velocities does not depent on the target atomic number.

Cross sections for Ar L-shell and Ne K-shell x-ray emission in heavy ion-atom collisions

The present work deals with a series of cross-section measurements for soft X-ray emission produced by Ar +, Ne +, H + on Ar and Ne +. The X radiation, which is detected by a proportional counter, corresponds to vacancies in the Ar L-shell and Ne K-shell. The cross section appears several orders of magnitude smaller for proton impact than for heavy-ion bombardment, thus showing the difference in excitation mechanisms. Mean fluorescence yields are deduced from our experimental emission cross sections and the Auger “excitation” cross sections of the innershells involved. It is observed that the fluorescence yield is influenced by the mechanism for primary vacancy creation. Finally, from the energy dependence of the cross section near threshold we determine critical internuclear distances for innershell excitation.