Accuracy of impact broadening models in low-density magnetized hydrogen plasmas

International audienceThe impact approximation used in the modelling of Stark profiles is examined when a magnetic field is present. Motivated by tokamak plasma spectroscopy, we calculate line shapes and $S$-matrix elements for the first Lyman lines of hydrogen with two models proposed for retaining simultaneously Stark and Zeeman effects in the impact limit. An evaluation of the accuracy of the two approaches is made with the help of a numerical simulation

A spectral line shape analysis of motional stark effect spectra

12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France)Recent observations of MSE spectra carried out on Tore-Supra show discrepancies between experimental and theoretical intensities calculated at equilibrium. We present here a kinetic model, based on the selectivity of excitation cross sections of Stark states in the parabolic basis. Redistribution due to ion-atom collisions among Stark states of level n=3 allow to calculate the population of Stark states. This model permits to improve significantly the agreement between measured and calculated MSE spectra

EUROfusion Integrated Modelling (EU-IM) capabilities and selected physics applications

International audienceRecent developments and achievements of the EUROfusion Code Development for Integrated Modelling project (WPCD), which aim is to provide a validated integrated modelling suite for the simulation and prediction of complete plasma discharges in any tokamak, are presented. WPCD develops generic complex integrated simulations, workflows, for physics applications, using the standardized European Integrated Modelling (EU-IM) framework. Selected physics applications of EU-IM workflows are illustrated in this paper

Couplages entre les phénomènes radiatifs et de transport dans les plasmas hors d'équilibre

Cette thèse présente une étude spectroscopique des plasmas magnétisés hors d'équilibre à l'aide des profils de raie spectrales. La première partie du travail porte sur les aspects fondamentaux des formalismes d'élargissement de raies dans de tels milieux. La séparation des coordonnées du centre de masse de l'émetteur est traitée de manière détaillée. Cette démarche permet de prendre en compte rigoureusement l'effet Stark motionnel, et de plus d'obtenir l'expression usuelle du profil Doppler à partir des premiers principes. La seconde partie du travail est consacrée à l'étude des profils de raies de deutérium dans les plasmas de bord de fusion par confinement magnétique. Dans un premier temps, une modélisation des parties centrales des raies est présentée. Celle-ci repose sur la prise en compte des sources de neutres liées à la paroi ainsi que sur un modèle de relaxation collisionnelle des neutres avec les ions du plasma. La prise en compte de cette relaxation permet d'obtenir une image cohérente des résultats des ajustements des paramètres du modèle aux spectres expérimentaux. De plus, il est alors possible d'obtenir des informations détaillées sur les sources de neutres. Enfin, un modèle incluant dans le calcul des profils Doppler la turbulence d'onde de dérive, omniprésente dans les plasmas de bord, est développé. L'intégration spatio-temporelle des fluctuations turbulentes par le spectromètre est traitée de manière statistique. Dans ce cadre, la forme de la fonction de distribution de probabilité des champs fluides fluctuants détermine les modifications introduites par la turbulence sur les profils de raie. Nous montrons en particulier comment des fluctuations intermittentes de vitesse fluide ou de température ionique peuvent conduire à des modifications significatives des régions du profil correspondant à des décalages en énergie importants.AIX-MARSEILLE1-BU Sci.St Charles (130552104) / SudocSudocFranceF

A new table of Balmer line shapes for the diagnostic of magnetic fusion plasmas

International audienc

Stark broadening by Lorentz fields in magnetically confined plasmas

International audienc

Calculating the simultaneous effect of ion dynamics and oscillating electric fields on Stark profiles

International audienceWe calculate hydrogen line shapes resulting from the simultaneous Stark effect of the plasma microfield and an oscillating electric field. Like laboratory plasmas, many kinds of space plasmas are affected by oscillating electric fields with a magnitude similar to that of the microfield. Here we focus on conditions where we expect that the effect of ion dynamics and oscillating electric are both significant. The combined effect of their dynamics on the quantum emitter is retained by a computer simulation coupled to a numerical integration of the Schrödinger equation. Our calculations are applied for conditions and transitions where significant changes in the line shape allow for a diagnostic of the plasma and oscillating field

Spectroscopic models for the characterization of energetic particle beams in tokamak edge plasmas

International audienc

A table of Balmer gamma line shapes for the diagnostic of magnetic fusion plasmas

International audienc

Hyperdiffusion of dust particles in a turbulent tokamak plasma

The effect of plasma turbulence on the trajectories of dust particles is investigated for the first time. The dynamics of dust particles is computed using the ad-hoc developed Dust Injection Simulator code, using a 3D turbulent plasma background computed with the TOKAM3X code. As a result, the evolution of the particle trajectories is governed by the ion drag force, and the shape of the trajectory is set by the Stokes number $St\propto a_d/n_0$, with $a_d$ the dust radius and $n_0$ the density at the separatrix. The plasma turbulence is observed to scatter the dust particles, exhibiting a hyperdiffusive regime in all cases. The amplitude of the turbulent spread of the trajectories $\Delta r^2$ is shown to depend on the ratio $Ku/St$, with $Ku\propto u_{rms}$ the Kubo number and $u_{rms}$ the fluctuation level of the plasma flow. These results are compared with a simple analytical model, predicting $\Delta r^2\propto (Ku/St)^2t^3$, or $\Delta r^2\propto (u_{rms}n_0/a_d)^2t^3$. As the dust is heated by the plasma fluxes, thermionic emission sets the dust charge, originally negative, to slightly positive values. This results in a substantial reduction of the ion drag force through the suppression of its Coulomb scattering component. The dust grain inertia is then no longer negligible, and drives the transition from a hyperdiffusive regime towards a ballistic one.This work is supported by the U.S. Department Of Energy under Contract No. DE-AC02-09CH11466 with Princeton University, and was granted access to the HPC resources of CINES, under the allocations A00505066912 and A00705066912 made by GENCI