Interpretations of the impact of cross-field drifts on divertor flows in DIII-D with UEDGE

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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5

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Nuclear Materials and Energy, Volume 12, pp. 1136-1140

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Simulations using the multi-fluid code UEDGE indicates that, in low confinement (L-mode) plasmas in DIII-D, poloidal projection of the ionization driven flows dominate poloidal particle flows in the divertor near the divertor plates, whereas E × B drift flows dominate the radial particle flows. In contrast, in high confinement (H-mode) conditions E × B drift flows dominate both poloidal and radial particle flows in the divertor in the vicinity of the strong gradient region near the separatrix. UEDGE indicates that the toroidal C2+ flow velocities in the divertor plasmas are mainly entrained within 30% to the background deuterium flow in both L- and H-mode plasmas in the plasma region where the CIII 465 nm emission is measured. Therefore, UEDGE indicates that the Doppler Coherence Imaging Spectroscopy (CIS), measuring the toroidal velocity of the C2+ ions, can provide insight to the deuterium flows in the divertor. Parallel-to-B velocity dominates the toroidal divertor flow; direct drift impact being less than 1%. Toroidal divertor flow is predicted to reverse when the magnetic field is reversed. This is explained by the parallel-B flow towards the nearest divertor plate corresponding to opposite toroidal directions in opposite toroidal field configurations.

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Jaervinen, A E, Allen, S L, Groth, M, McLean, A G, Rognlien, T D, Samuell, C M, Briesemeister, A, Fenstermacher, M, Hill, D N, Leonard, A W & Porter, G D 2017, 'Interpretations of the impact of cross-field drifts on divertor flows in DIII-D with UEDGE', Nuclear Materials and Energy, vol. 12, pp. 1136-1140. https://doi.org/10.1016/j.nme.2016.11.014