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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]

Nanometer-scale structures represent a novel and intriguing field, where scientists and engineers manipulate materials at the atomic and molecular scale levels to produce innovative materials. Carbon nanotubes constitute a relatively new class of materials exhibiting exceptional mechanical and electronic properties and were found to be promising candidates for molecular electronics, sensing or biomedical applications. Considering the bottom-up strategy in nanotechnology, the combination of the recognition properties of DNA with the electronic properties of single walled carbon nanotubes (SWNTs) seems to be a promising approach for the future of electronics. With the aim to assemble DNA with SWNTs, two complementary strategies have been envisioned: the covalent linkage of DNA on carboxylic groups of SWNTs under classical coupling condition and the non-covalent approach based on biotin-streptavidin molecular recognition properties. Here, we present and compare the results that we obtained with these two different methods; we want to objectively show the advantages and disadvantages of each approach. [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]

We present here a simple method to metallize DNA by Electroless Plating of palladium, a trusty metal for contacting SWNT devices. Indeed, DNA is a promising scaffolding candidate for molecular electronic bottom-up self-assembly approaches of SWNT devices. We report in this work the synthesis and characterization of individual Pd nanowires as thin as 30 nm showing ohmic behavior at room temperature. © 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]

Continued developments of quantitative spectroscopy and related atomic physics are originating from inertial and magnetic fusion research. In almost all experimental facilities, non-equilibrium phenomena are now a central issue and the interpretation of related spectroscopic data is a great challenge. We discuss new general diagnostic/spectroscopic approaches and usual point of views: high density methods and high density atomic physics for magnetic fusion research like ITER and the Virtual Contour Shape Kinetic Theory VCSKT which unifies low and high density plasma regimes and therefore allows to employ complex satellite transitions in non-equilibrium, non-LTE and non-Coronal plasmas. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The analysis of equilibrium conditions might be irrelevant to determine the importance of a certain set of atomic data. We show, that in non-equilibrium and optically thick plasmas intercombination transitions between highly excited states as well as higher order dielectronic satellite transitions are of extraordinary importance for diagnostics. In optically thin equilibrium plasmas, however, they are almost negligible. Numerical examples are presented for neutral helium in attached/detached plasmas as well as for dense laser produced plasmas. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Single wall carbon nanotubes (SWNTs) occupy a special place within molecular electronics. Indeed, they exist as semiconducting or metallic wires and have been used to demonstrate molecular devices like transistors, diodes or SET (single electron transistor). However, the future of this class of SWNT-based devices is strictly related to the development of a bottom-up self-assembly technique. The exceptional recognition properties of DNA molecule make it an ideal candidate for this task. Here, we describe a non-covalent method to connect carbon nanotubes to DNA strands using the streptavidin/biotin complex. Control experiments show that in absence of biotin, the DNA strand do not bind to SWNT. The binding of SWNT to DNA strand has also been carefully checked by washing experiments, showing the strength of the DNA anchorage on SWNTs. Combining this approach with molecular combing enable us to align nanotubes on substrate. [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 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]

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]

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

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]

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]