| 1. |
- Blom, Anders, et al.
(författare)
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Parametrization of the Zeeman effect for hydrogen-like spectra in high-temperature plasmas
- 2002
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335. ; 44:7, s. 1229-1241
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for parametrizing the Zeeman effect in hydrogen-like systems in high-temperature plasmas, where the fine-structure is completely unresolved. The method is based on the observation that the different polarization components behave collectively like separate entities, with simple relations. The entire Zeeman pattern can then be reduced to just three components, whose dependence on the magnetic field and the temperature can be described by only three numerical parameters. This makes it possible to include the influence of the Zeeman effect directly into ion temperature diagnostic procedures with minimal increase in the required computational effort and without the need for pre-calculated correction factors. We have tabulated such parametrizations-which are accurate for a wide range of fields and temperatures, even for cases when the total line-shape is no longer Gaussian-for 44 commonly studied hydrogen-like transitions. The effects of non-statistical population distribution in the upper sub-levels are briefly discussed, and we also note a temperature-dependent wavelength shift of the centre positions of the transitions.
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| 2. |
- Borges, F O, et al.
(författare)
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Weighted oscillator strengths and lifetimes for the SVII spectrum
- 2004
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Ingår i: Journal of Quantitative Spectroscopy & Radiative Transfer. - 0022-4073. ; 83:3-4, s. 751-763
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Tidskriftsartikel (refereegranskat)abstract
- The weighted oscillator strengths (gf) and the lifetimes presented in this work were carried out in a multiconfiguration Hartree-Fock relativistic approach. In this calculation, the electrostatic parameters were optimized by a least-squares procedure, in order to improve the adjustment to experimental energy levels. This method produces gf-values that are in better agreement with intensity observations and lifetime values that are closer to the experimental ones. In this work, we presented all the experimentally known electric dipole S VII spectral lines.
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| 3. |
- Jupén, Christer, et al.
(författare)
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Additions to the spectra of highly ionized molybdenum, Mo XXIV-Mo XXVIII
- 2003
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Ingår i: Physica Scripta. - 0031-8949. ; 68:4, s. 230-232
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Tidskriftsartikel (refereegranskat)abstract
- We have observed radiation from highly charged molybdenum ions in the JET tokamak plasmas. Spectra were recorded in the wavelength range 70-110 Angstrom, resulting in the classification of 15 new n = 3. Deltan = 0 transitions in Mo XXIV-Mo XXVIII.
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| 4. |
- Jupén, Christer, et al.
(författare)
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Analysis of 3s, 3p, 3d and 4f configurations of Sc XIII and V XV
- 2002
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Ingår i: Physica Scripta. - 0031-8949. ; 66:2, s. 150-158
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Tidskriftsartikel (refereegranskat)abstract
- In spectra obtained from foil-excited and laser-produced plasmas, we have identified 70 new lines as belonging to the spectra of fluorine-like scandium and vanadium ions, Sc XIII and V XV The new lines in the wavelength region from 70 to 600 Angstrom represent 2p(4)3s-3p, 3p-3d and 3d-4f transition arrays. The spectra have been interpreted with the aid of theoretical calculations, and the consistency of our derived 3s, 3p, 3d and 4f energy levels has been checked by means of isoelectronic comparisons.
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| 5. |
- Jupén, Christer, et al.
(författare)
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The spectrum and term system of SVII
- 2002
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Ingår i: Physica Scripta. - 0031-8949. ; 66:2, s. 140-149
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Tidskriftsartikel (refereegranskat)abstract
- The spectrum of six times ionized sulphur, S VII, has been investigated in the wavelength region 200-4000 Angstrom by means of the beam-foil and laser-produced plasma techniques. The analysis comprises 219 lines of which 105 are newly identified. The present work establishes 123 2s(2)2p(5)nl energy levels of which 66 are new. The level energies are determined with an internal consistency of better than 20 cm(-1). The observed level structure has been investigated by means of parametric calculations. The center-of-gravity ionization energy of the 2s(2)2p(5 2)P limit has been determined to 2 269 410 +/- 60 cm(-1). Of the identified 3s-3p and 3p-3d lines 27 are present in the solar coronal spectrum recorded by the SUMER instrument onboard the SOHO satellite. The present work adds 2 new solar identifications and improved wavelengths of some other solar coronal lines.
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| 6. |
- Martinson, Indrek, et al.
(författare)
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Atomic structure studies using fusion plasmas
- 2003
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Ingår i: Physica Scripta. - 0031-8949. ; 68:6, s. 123-132
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Forskningsöversikt (refereegranskat)abstract
- Atomic spectroscopy plays an important role in fusion research and extensive knowledge of atomic parameters is needed for plasma diagnostics. However, a magnetically confined hot plasma can be considered as a spectroscopic fight source which has some unique properties, including high temperature and low density. Fusion devices can therefore be used to tackle problems in basic atomic physics. This paper reviews the contributions to the structure of atomic ions, which have been obtained by the spectroscopy of fusion plasmas. Studies of highly charged ions, forbidden transitions, QED effects and connections between solar physics and fusion plasma physics will be discussed.
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| 7. |
- Mattioli, M, et al.
(författare)
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Experimental and simulated M-shell nickel spectra in the 14.4-18.0 nm region from magnetic fusion devices
- 2004
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 37:1, s. 13-40
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Tidskriftsartikel (refereegranskat)abstract
- Experimental M-shell nickel spectra in the 14.4-16.5 nm region from the JET tokamak (from both divertor and limiter configurations) and from the reversed field pinch RFX have been simulated. These spectra include lines from five ionization states, namely from K-like N-i9+ to P-like Ni13+ ions. For the JET limiter configuration the spectrum upper wavelength limit was higher (18.0 nm) and lines from Si-like Ni14+ ions were also observed. Collisional-radiative (CR) models have been built for these six Ni ions, considering electron collisional excitation and radiative decay as the main populating processes for the excited states. These models give photon emission coefficients (PECs) for the emitted tines at electron density (n(e)) and temperature (T-e) values corresponding to the experimental situations. Impurity modelling is performed using a 1D impurity transport code, calculating the steady state radial distribution of the Ni ions. The Ni line brightnesses are evaluated in a post-processing subroutine and simulated spectra are obtained. The spectrum from a single ion, in the absence of blendings, depends only on the T-e and n(e) values in the emitting shell of the ionization state considered. On the other hand, the superposition of these spectra depends on the experimental conditions, as a consequence of the fact that the ion charge distribution depends not only on the radial profiles of T-e and n(e) but also on the chosen ionization and recombination rate coefficients and on the radial profiles of the impurity transport coefficients in the region of the emitting shells. Since the aim of the paper is the investigation of the atomic physics of the M-shell ions, the section discussing the plasma physics phenomena is purposely limited. For each experimental spectrum a few simulations are presented, since a unique choice has not been found by selecting the input parameters of the transport code. The effect of the T-e and n(e) values on the emitting shells as well as the influence of line blendings on the single-ionization-degree spectra are stressed. These, in turn, are then compared with the predictions. For the n(e) range considered the PECs are practically independent of n(e). The T-e dependence is much reduced due to the fact that the spectral fits performed are actually comparisons of line ratios. The agreement found between experimental and simulated single-ionization-degree spectra gives confidence in the atomic data used in the CR models.
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