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10 results on '"Capes"'

1. Stark broadening of hydrogen lines in low-density magnetized plasmas

Author

M. Koubiti, C. Mossé, Sandrine Ferri, Yannick Marandet, L. Godbert-Mouret, J. Rosato, Roland Stamm, H. Capes, Physique des interactions ioniques et moléculaires (PIIM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
plasma density, plasma simulation, spectral line broadening, Tokamak devices, Stark effect, Lorentz transformation, 01 natural sciences, 010305 fluids & plasmas, Ion, symbols.namesake, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Principal quantum number, ddc:530, 010306 general physics, Physics, Zeeman effect, fusion reactor divertors, Divertor, Plasma, Magnetic field, symbols, spectral line breadth, Atomic physics
Abstract

Stark broadening of hydrogen lines in the presence of a magnetic field is revisited, with emphasis on the role of the ion component under typical conditions of magnetized fusion devices. An impact theory for ions valid at low density $({N}_{e}\ensuremath{\lesssim}{10}^{14}\text{ }{\text{cm}}^{\ensuremath{-}3})$ and taking into account the Zeeman degeneracy removal of the atomic states is developed. It is shown that the Stark widths of the Lorentz triplet components strongly depend on the magnetic field. The model is validated by a computer simulation method. For the lateral $\ensuremath{\sigma}$ components of $\text{Ly}\ensuremath{\alpha}$, we show that the impact approximation still holds for densities as high as ${N}_{e}\ensuremath{\sim}{10}^{15}\text{ }{\text{cm}}^{\ensuremath{-}3}$. In contrast, for the central $\ensuremath{\pi}$ component as well as for the other lines from low principal quantum number, significant discrepancies between the proposed theory and the simulation results appear at high density. Application to $D\ensuremath{\alpha}$ in tokamak divertor plasma conditions shows that, in this case, the quasistatic approximation becomes more relevant.

Published
2009

2. Spectral Line Shapes as a Diagnostic Tool in Magnetic Fusion.

Author

Stamm, R., Capes, H., Demura, A., Godbert-Mouret, L., Koubiti, M., Marandet, Y., Mattioli, M., Rosato, J., Rosmej, F., and Fournier, K. B.

Subjects
*NUCLEAR fusion, *HYDROGEN isotopes, *ZEEMAN effect, *STARK effect, *SPECTRAL line broadening, *TURBULENCE, *DOPPLER effect
Abstract

Spectral line shapes and intensities are used for obtaining information on the various regions of magnetic fusion devices. Emission from low principal quantum numbers of hydrogen isotopes is analyzed for understanding the complex recycling mechanism. Lines emitted from high principal quantum numbers of hydrogen and helium are dominated by Stark effect, allowing an electronic density diagnostic in the divertor. Intensities of lines emitted by impurities are fitted for a better knowledge of ion transport in the confined plasma. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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3. Spectroscopic analysis of tokamak edge plasmas.

Author

Koubiti, M., Godbert-Mouret, L., Che´rigier, L., Felts, B., Marandet, Y., Stamm, R., Touati, K., Capes, H., De Michelis, C., Escarguel, A., Guirlet, R., and Mattioli, M.

Subjects
TOKAMAKS, PLASMA spectroscopy, SPECTRAL line broadening, HELIUM, GLOW discharges
Abstract

The most intense deuterium and impurity line spectra, measured in the edge plasma of the Tore-Supra Tokamak operated with the Ergodic Divertor, are analysed in detail by comparison with theoretical profiles. Line profiles are calculated using a lineshape code which includes all level splitting and line broadening mechanisms (Zeeman, Fine structure, Doppler and Stark effects). Deuterium Balmer-alpha line spectra are fitted by considering three neutral populations with different temperatures characteristic of the main recycling mechanisms of the plasma ions (Molecular dissociation, reflection, and Charge exchange). Based on a least square fit method, a statistical study of symmetric spectra (sigma components with equal intensifies) has revealed a partial thermalization mechanism of recycled deuterium. Asymmetric spectra (sigma components with different intensities), observed in some discharges after wall conditioning with long helium glow discharges, are modelled by assuming a partial thermalization of neutrals through elastic collisions with the plasma ions. For impurity lines it is also necessary to consider at least 2 populations of emitters having different temperatures, with one of them moving towards the spectrometer. [ABSTRACT FROM AUTHOR]

Published
2001

4. Zeeman-Stark Profiles of Low-n Hydrogen Lines in Near Impact Regime.

Author

Rosato, J., Capes, H., Ferri, S., Godbert-Mouret, L., Koubiti, M., Marandet, Y., and Stamm, R.

Subjects
*ZEEMAN effect, *STARK effect, *HYDROGEN, *SPECTRAL line broadening, *SPECTRUM analysis
Abstract

Calculations of hydrogen Zeeman-Stark line profiles are presented and discussed when the conditions for impact ion broadening are almost satisfied. [ABSTRACT FROM AUTHOR]

Published
2008
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5. On the Use of Spectral Lines Emitted by Carbon Ions for Plasma Diagnostics in Magnetic Fusion Devices.

Author

Koubiti, M., Nakano, T., Capes, H., Ferri, S., Godbert-Mouret, L., Marandet, Y., Rosato, J., and Stamm, R.

Subjects
ZEEMAN effect, STARK effect, SPECTRAL line broadening, PLASMA diagnostics, PLASMA gases
Abstract

Profiles of the n = 5-6 (λ = 4658 Å) and n = 6-7 (7726 Å) lines emitted by Li-like carbon C+3 ions have been computed for plasma conditions of tokamak and stellarator divertors (Ne = 1019–1021 m-3, Te = 1–10 eV). The broadening and profiles of these lines are proposed to be used for plasma diagnostic purposes in particular to crosscheck the validity of the plasma parameters determined from the CIV line intensities measured in JT-60U tokamak. [ABSTRACT FROM AUTHOR]

Published
2008
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6. Broadening of deuterium lines emitted in edge plasmas of tokamak.

Author

Koubiti, M., Godbert-Mouret, L., Che´rigier, L., Felts, B., Marandet, Y., Stamm, R., Touati, K., Escarguel, A., Guirlet, R., Capes, H., Mattioli, M., and De Michelis, C.

Subjects
DEUTERIUM, TOKAMAKS, PLASMA gases, FOKKER-Planck equation, SPECTRAL line broadening, SPECTRUM analysis
Abstract

Line shapes of deuterium provide an important insight on the conditions of the edge plasmas of Tokamak. An analysis of line profiles of Dα reveals the existence of several populations with different temperatures. Our modeling of such profiles includes the description of the interaction between these populations with the help of a Fokker-Planck equation. For disruptive plasmas, the line shape of Dδ is shown to be broadened by Stark, Zeeman and Doppler effect, allowing an electronic density diagnostic. [ABSTRACT FROM AUTHOR]

Published
2001

7. Stark broadening of high-members of the helium diffuse series in divertor plasmas.

Author

M Koubiti, H Capes, L Godbert, Y Marandet, J Rosato, and R Stamm

Subjects
*STARK effect, *SPECTRAL line broadening, *HELIUM plasmas, *DIFFUSION, *TOKAMAKS, *APPROXIMATION theory, *PLASMA diagnostics
Abstract

Stark profiles of high-members (n [?] 7) of the helium triplet diffuse series 1s2p 3Po-1snd 3D are calculated for tokamak divertor conditions using dipole reduced matrix elements obtained with a hydrogenic approximation. It is shown that the so-called standard model of Stark broadening is particularly suited to the description of the isolated lines 1s2p 3Po-1snd 3D with n = 8-10. Applications to spectroscopic diagnostics in existing and future magnetic fusion-oriented devices like ITER are discussed. [ABSTRACT FROM AUTHOR]

Published
2010
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8. A parameterization of the Lyman α and Lyman β line shapes for radiation transport simulations in divertor plasmas

Author

Rosato, J., Reiter, D., Capes, H., Ferri, S., Godbert-Mouret, L., Koubiti, M., Marandet, Y., and Stamm, R.

Subjects
*PLASMA density, *TRANSPORT theory, *SIMULATION methods & models, *PLASMA devices, *TOKAMAKS, *RADIATION trapping, *SPECTRAL line broadening
Abstract

Abstract: At high divertor densities as foreseen in ITER, the hydrogen resonance radiation is trapped. This significantly affects the divertor dynamics. The model currently used for photon emission and absorption rates in EIRENE has been improved for the Lyman α and Lyman β lines. All line broadening mechanisms in the atom’s rest frame are retained, including Stark, Zeeman and fine structure effects. The influence of the ion dynamics on Stark broadening is described by a computer simulation technique. A parameterization of simulated spectral line shapes is proposed by using a fit subroutine, which allows for fast evaluation of the model in EIRENE. [Copyright &y& Elsevier]

Published
2009
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9. Investigation of C IV line broadening mechanisms for plasma diagnostics in magnetic fusion devices

Author

Koubiti, M., Nakano, T., Capes, H., Ferri, S., Godbert-Mouret, L., Marandet, Y., Rosato, J., and Stamm, R.

Subjects
*SPECTRAL line broadening, *PLASMA diagnostics, *FUSION reactors, *TOKAMAKS, *ELECTRON distribution, *TEMPERATURE effect, *STARK effect, *DOPPLER effect
Abstract

Abstract: The n =5–6 (λ =4658Å) and n =6–7 (λ =7726Å) spectral lines emitted by Li-like carbon ions C+3 from magnetic fusion devices based on carbon material are considered for plasma diagnostic purposes. The broadening mechanisms of these lines are examined for plasma conditions relevant to Tokamak divertors (electron densities and temperatures in the ranges 1019–1021 m−3 and 1–10eV). Under these conditions, the broadening mechanisms affecting the above lines are examined with and without the retaining of the magnetic field. The uncertainties on the deduced plasma parameters are also qualitatively estimated when only Stark and Doppler effects are retained while Zeeman and fine structure effects are ignored. The results presented are based on theoretical calculations carried out with the PPP line shape code and an atomic data basis built using Cowan’s code and the most accurate available atomic data for carbon. [Copyright &y& Elsevier]

Published
2009
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10. Stochastic processes for line shapes and intensities.

Author

Stamm, R., Hammami, R., Hannachi, I., Capes, H., Godbert-Mouret, L., Koubiti, M., Marandet, Y., and Rosato, J.

Subjects
*STOCHASTIC processes, *ATOMS, *STARK effect, *SPECTRAL line broadening, *EQUILIBRIUM plasmas, *PLASMA Langmuir waves
Abstract

Stochastic processes provide flexible and fast calculations for modeling dynamical interactions between an atom and charged particles. We use a stochastic renewal process for the plasma microfield being the cause of Stark broadening. The accuracy and improvement possibilities of Lyman profiles calculations with a renewal process are analyzed by comparing to ab initio simulations for ion broadening only. Stochastic processes may also be applied to out of equilibrium plasmas. We present our first results for the effect of Langmuir waves on a line broadened by electrons only, and for the changes of atomic populations submitted to strong temperature fluctuations. [ABSTRACT FROM AUTHOR]

Published
2014
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