Measurement of Impurity Emission Intensity Distribution in the Edge Region of LHD and Its Relation with Magnetic Field Structure

Kobayashi, Taisuke; Kobayashi, M.; Kuzmin, A.; Goto, M.; Tanaka, Hirohiko; Kawamura, G.; Peterson, B.J.; Iwama, Naofumi

doi:10.1585/pfr.13.3402030

Cited by 2 publications

(1 citation statement)

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“…3,4 Two-dimensional (2D) emission distribution measurements have been conducted so far with spectrometers in the edge region of LHD in order to study the relation between plasma transport and magnetic field structure. [5][6][7] However, the detailed comparison between the measured impurity emission and the magnetic field structure has been limited because of the line integration effect along the line of sight (LOS).…”

Section: Introductionmentioning

confidence: 99%

Single field-of-view tomographic imaging of 3D impurity emission distribution in magnetized edge plasma of LHD

Kobayashi

Iwama

et al. 2018

Review of Scientific Instruments

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A new tomographic scheme is proposed for reconstructing three dimensional (3D) impurity emission distributions from two dimensional (2D) measurements with a single field-of-view in the magnetized edge plasma in a Large Helical Device (LHD). The 2D image is obtained with a multi-channel fiber array spectrometer, which views the entire region of the edge stochastic magnetic layer of LHD, including divertor plates, divertor legs, the stochastic layer, and the last closed flux surface. The scheme introduces new regularization terms in the Lagrangian function, based on the transport feature in magnetized plasma that the transport parallel to the magnetic field lines is much faster than the transport across the magnetic field, thus assuming smooth distribution in the parallel direction. The scheme is benchmarked with the test data of 3D distribution in the measurement volume, where the effectiveness of the various regularization terms is surveyed and feasibility of the scheme is confirmed. The new scheme is applied to the experimental data in LHD for carbon impurity emissions of C 1+ and C 3+ , where the obtained distributions are discussed taking into account the plasma wall interaction and charge dependence of ionization potentials.

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