Impurity transport in ion- and electron-root confinement scenarios at Wendelstein 7-X

This paper reports on the observation of enhanced Ar impurity confinement in high density, turbulence reduced ion-root confinement (IRC) scenarios in Wendelstein 7-X (W7-X). Compared to the central electron-root confinement (CERC), Ar densities are substantially increased up to one order of magnitud...

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Bibliographic Details
Published in:Nuclear fusion 2021-11, Vol.61 (11), p.116018
Main Authors: Langenberg, A., Wegner, Th, Marchuk, O., García-Regaña, J.M., Pablant, N.A., Fuchert, G., Bozhenkov, S., Damm, H., Pasch, E., Brunner, K.-J., Knauer, J., Beurskens, M., Reimold, F., Wolf, R.C., W7-X Team, the
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
central electron-root confinement
confinement
impurity transport
ion root
microturbulence
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Summary:This paper reports on the observation of enhanced Ar impurity confinement in high density, turbulence reduced ion-root confinement (IRC) scenarios in Wendelstein 7-X (W7-X). Compared to the central electron-root confinement (CERC), Ar densities are substantially increased up to one order of magnitude and Ar flux profiles switch from slightly positive to pronounced negative fluxes all along the plasma radius in IRC. Estimations of the diffusive D and convective V transport parameter profiles using the STRAHL impurity transport code suggest a fundamentally different behavior in CERC and IRC with, compared to neoclassical values, high diffusive D and typical V profiles in CERC versus strongly reduced D and pronounced negative V profiles in IRC.
ISSN:0029-5515
1741-4326
DOI:10.1088/1741-4326/ac24d4