Polarization of atomic ensembles in ionized gases

Казанцев, С. А.; Polynovskaya, N Ya; Pyatnitskii, L. N.; Edelman, S.A.

doi:10.1070/pu1988v031n09abeh005620

Cited by 17 publications

(4 citation statements)

References 72 publications

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“…[90]. For the structure of a positive column plasma in a cylindrical cell a simplified approximation is adopted: the electrons are confined by the radial electric field and the current is sustained by the axial field [91]. In the distribution function of electron velocities loss cones are formed in high energies; this is due to the losses of these electrons at the boundary sheath (of the order of the Debye length) to the wall.…”

Section: Gas Discharge Plasmasmentioning

confidence: 99%

Plasma polarization spectroscopy

Fujimoto

Казанцев

1997

Plasma Phys. Control. Fusion

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In the density matrix formalism, the ensemble of atoms or ions is expressed in terms of population and alignment of excited levels and the ground state. The population of an excited level determines the intensity of an emission line originating from this level and the alignment gives rise to the linear polarization of this line. Spatially anisotropic collisions induce transitions between the populations and the alignments; for example, an alignment along with a population is produced by a beam of electrons in an excited level from the ground-state population. Thus, an anisotropic plasma produces polarized radiations, and by plasma polarization spectroscopy (PPS) we can investigate the anisotropic, and thus non-thermal, features of the plasma. The angular distribution of the perturber velocities is expanded in terms of Legendre polynomials. The expansion coefficients and the relevant cross sections for the transitions among the populations and the alignments yield the rate coefficients for these transitions. For the ensemble of atoms or ions immersed in the plasma, coupled rate equations are constructed for the populations and the alignments of excited levels. We review the present status of our knowledge of the collision cross sections for various collision processes. Several experimental observations of PPS performed so far are reviewed, which include those on a tokamak plasma, laser produced plasmas, various discharge plasmas and solar flares. We discuss what kind of information could be obtained from PPS.

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Section: Gas Discharge Plasmasmentioning

confidence: 99%

Plasma polarization spectroscopy

Fujimoto

Казанцев

1997

Plasma Phys. Control. Fusion

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“…The access to radiation helicity describing the rotation of light polarization vector is obtained applying the circular photogalvanic effect (CPGE) in quantum wells (QWs) [1,2]. Besides other applications, THz ellipsometry can be of particular interest for control of current density profiles which is important for tokamak operation [3,4]. Because the sensitivity of both detector elements varies with the polarization state of radiation, a third detector is applied to measure intensity.…”

Section: Introductionmentioning

confidence: 99%

Picosecond Polarisation Detector for Infrared and Terahertz Radiation

et al. 2007

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We report on a room temperature detector of laser light ellipticity allowing determination of azimuth, ellipse shape, and the sense of rotation of the light vector with subnanosecond time resolution. The detector operation is demonstrated for THz radiation detection, but the same technique can be extended for detection of infrared or visible light. The detection system is based on the simultaneous measurement of three different photocurrents obtained from three unbiased semiconductor detector elements stacked in-line together.

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“…These equations contain, as parameters, magnetic-sublevel-specific electron collision cross sections. One important parameter, which is of concern here, is the alignment creation cross section associated with elastic scattering, which is defined (Kazantsev et al 1988) as…”

Section: Plasma Polarization Spectroscopymentioning

confidence: 99%

Elastic electron scattering by laser-excited¹³⁸Ba( ... 6s6p¹P₁) atoms

Trajmar

Kanik

Khakoo

et al. 1999

J. Phys. B: At. Mol. Opt. Phys.

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Abstract.The results of a joint experimental and theoretical study concerning elastic electron scattering by laser-excited 138 Ba(. . . 6s6p 1 P 1 ) atoms are described. These studies demonstrate several important aspects of elastic electron collisions with coherently excited atoms, and are the first such studies. From the measurements, collision and coherence parameters, as well as cross sections associated with an atomic ensemble prepared with an arbitrary in-plane laser geometry and linear polarization (with respect to the collision frame), or equivalently with any magnetic sublevel superposition, have been obtained at 20 eV impact energy and at 10 • , 15 • and 20 • scattering angles. The convergent close-coupling (CCC) method was used within the non-relativistic LS-coupling framework to calculate the magnetic sublevel scattering amplitudes. From these amplitudes all the parameters and cross sections at 20 eV impact energy were extracted in the full angular range in 1 • steps. The experimental and theoretical results were found to be in good agreement, indicating that the CCC method can be reliably applied to elastic scattering by 138 Ba(. . . 6s6p 1 P 1 ) atoms, and possibly to other heavy elements when spin-orbit coupling effects are negligible. Small but significant asymmetry was observed in the cross sections for scattering to the left and to the right. It was also found that elastic electron scattering by the initially isotropic atomic ensemble resulted in the creation of significant alignment. As a byproduct of the present studies, elastic scattering cross sections for metastable 138 Ba atoms were also obtained.

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Polarization of atomic ensembles in ionized gases

Cited by 17 publications

References 72 publications

Plasma polarization spectroscopy

Plasma polarization spectroscopy

Picosecond Polarisation Detector for Infrared and Terahertz Radiation

Elastic electron scattering by laser-excited¹³⁸Ba( ... 6s6p¹P₁) atoms

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Polarization of atomic ensembles in ionized gases

Cited by 17 publications

References 72 publications

Plasma polarization spectroscopy

Plasma polarization spectroscopy

Picosecond Polarisation Detector for Infrared and Terahertz Radiation

Elastic electron scattering by laser-excited138Ba( ... 6s6p1P1) atoms

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Product

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Elastic electron scattering by laser-excited¹³⁸Ba( ... 6s6p¹P₁) atoms