Theory of excitation of He-like and Li-like atomic sublevels by directive electrons: application to X-ray line polarisation

Inal, M K; Dubau, J.

doi:10.1088/0022-3700/20/16/028

Cited by 154 publications

(101 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This can lead to polarization, if the nonthermal electrons fall into the right energy range. 27,28 Figure 13 shows polarization effects for the prominent lines of the ArXVII spectrum. The results were obtained from modeling calculations, which assume a beam of monoenergetic electrons in the energy range from 3.2 to 136 keV.…”

Section: Polarization During Ohmic Dischargesmentioning

confidence: 99%

“…29 The line ratios for the two phases, corrected for profile effects as described in Ref. 28, are given in Table II for both spectrometers. Since the ratios are equal to within the errors of the measurements, it can be concluded that, within the sensitivity of the instrument, no polarization of the radiation was found.…”

Section: Polarization During Ohmic Dischargesmentioning

confidence: 99%

See 1 more Smart Citation

High-resolution x-ray crystal spectrometer/polarimeter at torus experiment for technology oriented research-94

Weinheimer

Ahmad

Herzog

et al. 2001

Review of Scientific Instruments

View full text Add to dashboard Cite

A high-resolution x-ray polarimeter has been installed at the torus experiment for technology oriented research ͑TEXTOR-94͒. The instrument consists of two spectrometers in Johann geometry, utilizing the dependence of Bragg reflection on the polarization. The dispersion plane of the so-called horizontal spectrometer coincides with the midplane of the tokamak, whereas the dispersion plane of the so-called vertical spectrometer lies perpendicular to the midplane of the tokamak. Both spectrometers operate with cylindrically bent quartz crystals of dimensions 153 mmϫ38 mmϫ0.7 mm with a 2d spacing of 4.9130 Å. The radii of curvature of the horizontal and vertical spectrometer crystals are 3820 mm and 4630 mm, respectively. The detectors are multiwire proportional counters having a large entrance window of 180 mmϫ90 mm, with a high count rate capability of up to 2.5ϫ10 5 photons/s, and a spatial resolution of 0.4-0.65 mm, depending on the count rate. The unique data acquisition system makes it possible to record up to 8192 spectra per TEXTOR-94 discharge to study fast events and impurity transport. The instruments are sensitive to spurious amounts of argon in hydrogen or deuterium discharges and aim for x-ray polarization measurements and other core plasma diagnostics like electron temperature, ion temperature, plasma rotation, impurity transport, and relative abundance of Ar 15ϩ /Ar 16ϩ . The first measurements of toroidal rotation speed, ion and electron temperatures show a very good agreement with charge exchange recombination spectroscopy ͑XRS͒ and electron cyclotron emission ͑ECE͒ diagnostics available at TEXTOR-94. The measured values of the ratio Ar 15ϩ /Ar 16ϩ are higher than that predicted from coronal equilibrium. The ratio depends strongly upon the electron density both for ohmic and neutral beam injection cases. This suggests that the charge state distribution is also dependent on diffusion and charge exchange processes in the plasmas.

show abstract

Section: Polarization During Ohmic Dischargesmentioning

confidence: 99%

Section: Polarization During Ohmic Dischargesmentioning

confidence: 99%

High-resolution x-ray crystal spectrometer/polarimeter at torus experiment for technology oriented research-94

Weinheimer

Ahmad

Herzog

et al. 2001

Review of Scientific Instruments

View full text Add to dashboard Cite

show abstract

“…Fundamental quantum mechanical studies are necessary in order to provide insights into the mechanism and 1 present address: Gulf Coast Community College, Panama City, FL 32401, USA characteristics of polarized line emissions. Most of this work was done using densitymatrix formalism [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Cascade effects on the polarization of He-like Fe1s2l−1s2x-ray line emission

et al. 2007

View full text Add to dashboard Cite

Abstract. We calculate X-ray line polarization degrees for cases with axial symmetry using a collisional-radiative magnetic-sublevel atomic kinetics model and the properties of multipole radiation fields. This approach is well-suited for problems where the alignment is determined by the competition between many atomic processes. We benchmark this method against polarization measurements performed at the Livermore electron beam ion trap, and we study the 3-to-2 cascade effects on the polarization of 2-to-1 lines in He-like Fe.

show abstract

“…Even though the relation (5) has been derived for the electron recombination into initially hydrogen-like ions |α i J i ≡ |n 0 j 0 , it can certainly be applied for an arbitrary system with a single valence electron outside of closed shell. In Section 3, for example, we apply equation (5) to study the alignment following the electron capture into the 1s 2 2s 3d 3/2 J f = 1, 2 states of (initially) lithium-like heavy ions.…”

Section: Alignment Parameters Within the Independent Particle Modelmentioning

confidence: 99%

“…A great number of case studies have therefore been performed in order to explore the angular and polarization properties of the subsequent decay and to derive the alignment of highly-charged ions, following the ion-atom (or ion-electron) collisions. For the electron-impact excitation of few-electron ions, for instance, these theoretical [5][6][7][8] and experimental [9][10][11][12] a e-mail: surz@mpi-hd.mpg.de studies had a strong impact upon the diagnostics of hightemperature laboratory and astrophysical plasmas as well as for probing relativistic effects in simple atomic systems. Much attention has been paid also onto the magnetic sublevel population of the ionic states as produced by the inner-shell (impact) ionization, for which detailed calculations have been performed both, within the nonrelativistic [2,13,14] as well as the relativistic distorted-wave theory [15,16].…”

Section: Introductionmentioning

confidence: 99%

Electron capture into few-electron heavy ions: Independent particle model

2007

View full text Add to dashboard Cite

Abstract. We apply the density matrix theory to re-investigate the radiative electron capture into heavy ions with one valence electron. Attention has been paid particularly to the magnetic sublevel population of the residual ions, as described in terms of alignment parameters. Simple method, based on an independent particle model, which takes into account the Pauli principle, is proposed for evaluating the alignment of the excited ionic states. By making use of this method, detailed calculations are performed for electron capture into (initially) hydrogen-like and lithium-like europium, gold and uranium ions, and are compared with the results of the multiconfiguration Dirac-Fock approach.As seen from the calculations and from the comparison with available experimental results, the independent particle model provides a good estimate for the alignment parameters of few-electron heavy ions. Therefore, our simple model may help to understand the basic properties of the X-ray emission from heavy, few-electron ions without the need for invoking sophisticated MCDF calculations. PACS

show abstract

Theory of excitation of He-like and Li-like atomic sublevels by directive electrons: application to X-ray line polarisation

Cited by 154 publications

References 24 publications

High-resolution x-ray crystal spectrometer/polarimeter at torus experiment for technology oriented research-94

High-resolution x-ray crystal spectrometer/polarimeter at torus experiment for technology oriented research-94

Cascade effects on the polarization of He-like Fe1s2l−1s2x-ray line emission

Electron capture into few-electron heavy ions: Independent particle model

Contact Info

Product

Resources

About