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An overview of issues related to the interplay between atomic process and turbulence in the peripheral regions of magnetically confined fusion devices is presented. Both atomic processes and turbulence play key roles for fusion, but have most of the time been treated separately. The effects of fluctuations on the time averaged ionization balance, on the transport of neutral particles (atoms and molecules) are discussed, using stochastic models to generate fluctuations with statistically relevant properties. Then applications to optical diagnostics of turbulence, namely gas puff imaging and beam emission spectroscopy are discussed. [ABSTRACT FROM AUTHOR]

We investigate the Stark broadening of hydrogen lines in tokamark edge plasma conditions in the presence of a beam of relativistic "runaway" electronis. The possibility for a diagnostic involving passive spectroscopy is discussed. [ABSTRACT FROM AUTHOR]

We report on a Stark line shape model for the diagnostic of tokamak edge plasmas. In specific secenarios, plasma discharges are carried out at high density regimes, sufficiently so that the spectral lines emitted by the neutral atoms present in the edge and in the divertor region are affected by the plasma microscopic electric field (Stark broadening). We present new line shpe calculations, carried out for diagnostic purposes in the context of the MST1 (Medium Sized Tokamak) European campaign. The role of the magnetic field (Zeeman effect) on line spectra is discussed. [ABSTRACT FROM AUTHOR]

In order to provide a general framework where the Stark broadening of atomic lines in plasmas can be calculated, we model the plasma stochastic electric field by using the CTRW approach [1,2]. This allows retaining non Markovian terms in the Schrödinger equation averaged over the electric field fluctuations. As an application we consider a special case of a non separable CTRW process, the so called Kangaroo process [3]. An analytic expression for the line profile is finally obtained for arbitrary waiting time distribution functions. An application to the hydrogen Lyman α line is discussed. [ABSTRACT FROM AUTHOR]

Stark broadening of atomic lines in plasmas is calculated by modelling the plasma stochastic electric field using the CTRW approach [1,2]. This allows retaining non Markovian terms in the Schrödinger equation averaged over the electric field fluctuations. As an application we consider a special case of a non separable CTRW process, the so called Kangaroo process [3]. An analytic expression for the line profile is presented for arbitrary waiting time distribution functions. A preliminary application to the hydrogen Lyman α line is discussed. [ABSTRACT FROM AUTHOR]

The state of art of the line shape modeling techniques involved in tokamak edge plasma spectroscopy is reported, in the context of the preparation for ITER. Hydrogen spectra are calculated assuming a line-of-sight crossing a 2D-plasma background obtained from numerical simulations. The Doppler, Zeeman and Stark effects are retained. Ion dynamics effects are accounted for by using the numerical simulation method. The possibility for a line shape-based diagnostic of the ITER divertor plasma is examined through fittings of simulated spectra and comparison with the input plasma fields. [ABSTRACT FROM AUTHOR]

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]

In this work, the influence of the turbulent plasma temperature fluctuations brought on the Hα Doppler line shape is investigated. We show that the core of the line profile is modified by the plasma turbulence. The consequences on the ion temperature determination from Doppler line profile analysis are discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this work we analyze the role played by fine structure in the modeling of spectral line shape. In the case of non hydrogenic impurities, fine structure obviously cannot be neglected since the corresponding components are often resolved. This is generally not the case for hydrogenic lines, which have larger Doppler widths. Nevertheless, we show that in some tokamak plasmas conditions fine structure must be taken into account so as to ensure accurate line width measurements. We present a numerical code developed by our group, which is able to calculate line shapes emitted by any kind of atoms perturbed by electric and magnetic fields. Magnetic field effects on fine structure spectra of both impurities and deuterium are investigated for tokamak edge conditions, i.e. for emitter temperature varying from a fraction of eV to a few tens of eV, and for magnetic field in the range of 0–5 teslas. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The far wings of intense D[sub α] lines measured at the edge of the Tore Supra Tokamak are found to exhibit a power-law behavior. The characteristic exponent is not far from two. Since the low density roles out thermal Stark broadening, we discuss non thermal effects which may arise from the edge plasma drift-wave turbulence. We suggest that both the Stark and the Doppler profile could be affected by the turbulence. [ABSTRACT FROM AUTHOR]

Characterizing edge plasmas is an important issue for a better control of the plasma wall interaction, and the recycling of thermonuclear fuel. We use line profiles emitted by hydrogen isotopes, helium and impurity ions, as a non intrusive probe for diagnosing the density and temperature of edge particles. An analysis of line wings of Dα has been performed with the aim of investigating the dynamics of edge particles. [ABSTRACT FROM AUTHOR]

A Stark line shape code has been coupled to a collisional-radiative model and to an analytical model for the merging into the continuum of the Balmer lines. The coupled codes have been used for temperature and density diagnostics of detached plasmas. In contrast with the occupation probability and the lowering of the continuum edge approaches, the analytical line merging model used here consists in the use of Lorentzian profiles for highly excited Balmer transitions of deuterium. In addition, high-n helium lines (1s2p-1snl) up to n=12 observed in the JET divertor have been preliminary analyzed. The intensities of these experimental helium lines decrease more rapidly with the upper state nl than the intensities calculated with state populations at local thermodynamic equilibrium (LTE). [ABSTRACT FROM AUTHOR]

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]

The effects of time ordering on line shapes are investigated for the dynamic ionic broadening of the Lyman alpha line in hydrogen plasmas. The difference between calculations with and without time ordering is calculated for an electric field created by a single particle, and for a thermal average over plasma configurations with moderate temperature and density. [ABSTRACT FROM AUTHOR]

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]

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

Modelling of hydrogen line profiles in the ITER divertor plasma entails several challenges. Because of the high density (Ne>1014cm-3) low temperature (kTe<2eV) expected in the magnetized plasma close to the wall, both Stark broadening and Zeeman splitting have to be taken into account in line shape calculations, [1]. Moreover, the conditions are such that the ion dynamics has to be retained in Stark broadening calculations, the presence of a high magnetic field (B∼5T) introduces couplings between Stark and Zeeman effects, which can significantly alter the profile [2,3]. We present here Balmer lines obtained by numerical simulations based on a standard Molecular Dynamics technique, of the plasma in an external magnetic field. The simulated profiles are compared to experimental ones obtained in Plasma Surface Interaction (PSI) experiments which are carried out on Pilot-PSI of FOM. [ABSTRACT FROM AUTHOR]

First investigations of the effect of ion temperature fluctuations on Doppler spectral line shapes emitted in tokamak edge plasmas are reported on. It is shown that hot charge exchange neutrals have to be taken into account in the analysis. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this work we investigate line shapes in a divertor plasma and we study the effects due to the hydrodynamic turbulence. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

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]