Doppler line shape model for the W I 5d 5 6s—5d 5 6p transition at 400.9 nm in tokamaks

International audienceTungsten spectroscopy is known to be a useful tool for quantifying W fluxes in tokamaks. We aim to analyze how background plasma parameters influence the W spectral-line shape measured in the divertor and scrape-off layer and what information could be retrieved from such an analysis. To that end, a Monte Carlo model is developed to simulate the line shape of the 400.9 nm W I line emitted by physically sputtered W ions from plasma facing components. The influence of background plasma parameters (ion and electron temperature) and geometrical effects (detector positioning with respect to the eroded surface) are investigated. The effect of Zeeman splitting on the spectral line-shape is also explored. A set of requirements for the experimental setup needed to measure the analyzed spectral line features with line peak shifts of the order of 10 −2Å and peak widths in the range from 10 −1Å to 10 −2Å are proposed. These requirements are shown to be experimentally accessible, through the installation of specific high-resolution spectrometers not typically used on magnetic fusion devices

First efforts in numerical modeling of tungsten migration in WEST with SolEdge2D-EIRENE and ERO2.0

The first simulations of tungsten migration in WEST are performed with the SolEdge2D-EIRENE and ERO2.0 codes to support experimental investigations into the erosion of plasma-facing components and plasma impurity content. The impact of varying the background density on (i) the amount of tungsten penetrating the confined plasma, (ii) the promptly redeposited fraction, and (iii) the erosion and deposition patterns on the wall, is investigated under the working assumptions of a simplified toroidally symmetric wall contour, typical L-mode values of the transport coefficients, and deuterium plasma with a 1% oxygen content. The lower divertor is found to be the main zone of net tungsten erosion and deposition. This pattern is reduced at high background density due to the higher promptly redeposited fraction

First efforts in numerical modeling of tungsten migration in WEST with SolEdge2D-EIRENE and ERO2.0

The first simulations of tungsten migration in WEST are performed with the SolEdge2D-EIRENE and ERO2.0 codes to support experimental investigations into the erosion of plasma-facing components and plasma impurity content. The impact of varying the background density on (i) the amount of tungsten penetrating the confined plasma, (ii) the promptly redeposited fraction, and (iii) the erosion and deposition patterns on the wall, is investigated under the working assumptions of a simplified toroidally symmetric wall contour, typical L-mode values of the transport coefficients, and deuterium plasma with a 1% oxygen content. The lower divertor is found to be the main zone of net tungsten erosion and deposition. This pattern is reduced at high background density due to the higher promptly redeposited fraction

First efforts in numerical modeling of tungsten migration in WEST with SolEdge2D-EIRENE and ERO2.0

The first simulations of tungsten migration in WEST are performed with the SolEdge2D-EIRENE and ERO2.0 codes to support experimental investigations into the erosion of plasma-facing components and plasma impurity content. The impact of varying the background density on (i) the amount of tungsten penetrating the confined plasma, (ii) the promptly redeposited fraction, and (iii) the erosion and deposition patterns on the wall, is investigated under the working assumptions of a simplified toroidally symmetric wall contour, typical L-mode values of the transport coefficients, and deuterium plasma with a 1% oxygen content. The lower divertor is found to be the main zone of net tungsten erosion and deposition. This pattern is reduced at high background density due to the higher promptly redeposited fraction