scholarly journals Review of Recent Advances in the Analytical Theory of Stark Broadening of Hydrogenic Spectral Lines in Plasmas: Applications to Laboratory Discharges and Astrophysical Objects

Atoms ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 50 ◽  
Author(s):  
Eugene Oks
Keyword(s):  
Magnetic Field ◽  
White Dwarfs ◽  
Spectral Lines ◽  
Analytical Theory ◽  
Magnetic Fusion ◽  
Stark Broadening ◽  
Hydrogen Atoms ◽  
Analytical Treatment ◽  
Hydrogen Deuterium ◽  
Hydrogen Lines

There is presented an overview of the latest advances in the analytical theory of Stark broadening of hydrogenic spectral lines in various types of laboratory and astrophysical plasmas. They include: (1) advanced analytical treatment of the Stark broadening of hydrogenic spectral lines by plasma electrons; (2) center-of-mass effects for hydrogen atoms in a nonuniform electric field: applications to magnetic fusion, radiofrequency discharges, and flare stars; (3) penetrating-ions-caused shift of hydrogenic spectral lines in plasmas; (4) improvement of the method for measuring the electron density based on the asymmetry of hydrogenic spectral lines in dense plasmas; (5) Lorentz–Doppler broadening of hydrogen/deuterium spectral lines: analytical solution for any angle of observation and any magnetic field strength, and its applications to magnetic fusion and solar physics; (6) Revision of the Inglis-Teller diagnostic method; (7) Stark broadening of hydrogen/deuterium spectral lines by a relativistic electron beam: analytical results and applications to magnetic fusion; (8) Influence of magnetic-field-caused modifications of the trajectories of plasma electrons on shifts and relative intensities of Zeeman components of hydrogen/deuterium spectral lines: applications to magnetic fusion and white dwarfs; (9) Influence of magnetic-field-caused modifications of trajectories of plasma electrons on the width of hydrogen/deuterium spectral lines: applications to white dwarfs; (10) Stark broadening of hydrogen lines in plasmas of electron densities up to or more than Ne~1020 cm−3; and, (11) The shape of spectral lines of two-electron Rydberg atoms/ions: a peculiar Stark broadening.

Application of the Dipole Model to Selected Magnetic White Dwarfs

1989 ◽  
Vol 8 (2) ◽  
pp. 148-153 ◽  
Author(s):  
N. Achilleos ◽  
D. T. Wickramasinghe
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Observational Data ◽  
White Dwarfs ◽  
Zeeman Splitting ◽  
Polarization Data ◽  
Detailed Model ◽  
Field Geometry ◽  
Hydrogen Lines ◽  
The Magnetic Field

AbstractVarious authors have reported observations of the flux and circular polarization for the three stars PG 1658 + 441, PG 1533 − 057 and K 813 − 14. On the basis of the observational data, the stars were classified as magnetic white dwarfs. To place constraints on the magnetic field strengths and geometries of these stars, the relevant authors qualitatively compared the data with available theory and, in two cases, used a model of optically thin hydrogen threaded by a magnetic field.In this paper we use a more detailed model for magnetic white dwarfs to assess the results previously obtained for these three stars. We find that, in two cases, the observed spectra can be explained by the Zeeman splitting of hydrogen lines in a stellar magnetic field which takes the form of a dipole situated at the centre of the star. The circular polarization data for PG 1658 + 441, however, may indicate a field geometry for this star which is significally different from that of a centred dipole.

scholarly journals Discovery of six new strongly magnetic white dwarfs in the 20 pc local population

2020 ◽  
Vol 643 ◽  
pp. A134 ◽  
Author(s):  
Stefano Bagnulo ◽  
John D. Landstreet
Keyword(s):  
Magnetic Field ◽  
White Dwarfs ◽  
Local Population ◽  
Longitudinal Component ◽  
Spectral Lines ◽  
Total Production ◽  
Milky Way Galaxy ◽  
Circular Polarisation ◽  
Cool White Dwarfs ◽  
The Magnetic Field

The sample of white dwarfs included in the local 20 pc volume documents, fairly accurately, the total production of white dwarfs over roughly 10 Gyr of stellar evolution in this part of the Milky Way Galaxy. In this sample, we have been systematically searching for magnetic white dwarfs. Here we report the discovery of six new magnetic white dwarfs, with a field strength from a few MG to about 200 MG. Two of these stars show H lines that are split and polarised by the magnetic field. One star shows extremely weak spectral lines in intensity, to which highly polarised narrow features correspond. The three other stars have featureless flux spectra, but show continuum polarisation. These new discoveries support the view that at least 20% of all white dwarfs in the local 20 pc volume have magnetic fields, and they fully confirm the suspicion that magnetism is a common rather than a rare characteristic of white dwarfs. We discuss the level and the handedness of the continuum polarisation in the presence of a magnetic field in cool white dwarfs. We suggest that a magnetic field with a 15 MG longitudinal component produces 1% of continuum circular polarisation. We have also shown that the problem of cross-talk from linear to circular polarisation of the FORS2 instrument, used in our survey, represents an obstacle to accurate measurements of the circular polarisation of faint white dwarfs when the background is illuminated, and polarised, by the moon.

scholarly journals INFLUENCE OF LONGITUDINAL MAGNETIC FIELD IN THE MPC CHANNEL ON THE DENSITY OF GENERATED PLASMA STREAM

2021 ◽  
pp. 57-60
Author(s):  
A.K. Marchenko ◽  
O.V. Byrka ◽  
V.A. Makhlai ◽  
S.S. Herashenko ◽  
D.G. Solyakov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Axial Magnetic Field ◽  
Plasma Electron ◽  
Spectral Lines ◽  
Plasma Stream ◽  
Stark Broadening ◽  
Density Distributions ◽  
Average Electron ◽  
Field Influence

The paper is devoted to experimental measurements and analysis of parameters of the plasma streams generated by magnetoplasma compressor (MPC) upgraded with an external axial magnetic field. Influence of the external axial magnetic field of 0.24 T on helium plasma streams (P=2 Torr) has been studied. The measurements of average electron density distributions were performedboth with and without an external axial B-field. Distributions of plasma electron density Ne (L) were measured with spectroscopy in the plasma stream and in the compression zone using Stark broadening of He I and He II spectral lines. Plasma-surface interaction processes were also analyzed.

Stark broadening of hydrogen lines in magnetic fusion plasmas

2017 ◽  
Author(s):  
J. Rosato ◽  
L. Godbert-Mouret ◽  
M. Koubiti ◽  
Y. Marandet ◽  
R. Stamm
Keyword(s):  
Magnetic Fusion ◽  
Fusion Plasmas ◽  
Stark Broadening ◽  
Hydrogen Lines
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