Core radial electric field and transport in Wendelstein 7-X plasmas

Pablant, N. A.; Langenberg, A.; Alonso, A.; Beidler, C. D.; Bitter, M.; Bozhenkov, S.; Burhenn, R.; Beurskens, M.; Delgado-Aparicio, L.; Dinklage, A.; Fuchert, G.; Gates, D.; Geiger, J.; Hill, K. W.; Hofel, U.; Hirsch, M.; Knauer, J.; Kramer-Flecken, A.; Landreman, M.; Lazerson, S.; MaaBberg, H.; Marchuk, O.; Massidda, S.; Neilson, G. H.; Pasch, E.; Satake, S.; Svennson, J.; Traverso, P.; Turkin, Y.; Valson, P.; Velasco, J. L.; Weir, G.; Windisch, T.; Wolf, R. C.; Yokoyama, M.; Zhang, D.

doi:10.1063/1.4999842

Core radial electric field and transport in Wendelstein 7-X plasmas

Journal Article · Mon Feb 12 00:00:00 EST 2018 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4999842· OSTI ID:1430535

^[1]; Langenberg, A. ^[2]; ^[3]; Beidler, C. D. ^[2]; Bitter, M. ^[1]; Bozhenkov, S. ^[2]; Burhenn, R. ^[2]; Beurskens, M. ^[2]; Delgado-Aparicio, L. ^[1]; Dinklage, A. ^[2]; Fuchert, G. ^[2]; ^[1]; Geiger, J. ^[2]; Hill, K. W. ^[1]; Hofel, U. ^[2]; Hirsch, M. ^[2]; ^[2]; ^[4]; Landreman, M. ^[5]; Lazerson, S. ^[1] more »

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Max-Planck-Inst. fur Plasmaphysik, Greifswald (Germany)
Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Lab. Nacional de Fusion
Forschungszentrum Julich (Germany). Inst. fur Energie- und Klimaforschung (IEK)
Univ. of Maryland, College Park, MD (United States)
Auburn Univ., AL (United States)
National Inst. for Fusion Science, Toki (Japan); Graduate Univ. for Advanced Studies (SOKENDAI), Toki (Japan)

The results from the investigation of neoclassical core transport and the role of the radial electric field profile (E_r) in the first operational phase of the Wendelstein 7-X (W7-X) stellarator are presented. In stellarator plasmas, the details of the E_r profile are expected to have a strong effect on both the particle and heat fluxes. Investigation of the radial electric field is important in understanding neoclassical transport and in validation of neoclassical calculations. The radial electric field is closely related to the perpendicular plasma flow (u_⊥) through the force balance equation. This allows the radial electric field to be inferred from measurements of the perpendicular flow velocity, which can be measured using the x-ray imaging crystal spectrometer and correlation reflectometry diagnostics. Large changes in the perpendicular rotation, on the order of Δu_⊥~ 5 km/s (ΔE_r ~12 kV/m), have been observed within a set of experiments where the heating power was stepped down from 2 MW to 0.6 MW. These experiments are examined in detail to explore the relationship between heating power temperature, and density profiles and the radial electric field. Finally, the inferred E_r profiles are compared to initial neoclassical calculations based on measured plasma profiles. The results from several neoclassical codes, sfincs, fortec-3d, and dkes, are compared both with each other and the measurements. Finally, these comparisons show good agreement, giving confidence in the applicability of the neoclassical calculations to the W7-X configuration.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: Euratom Research and Training Programme; USDOE

Contributing Organization:: W7-X Team

Grant/Contract Number:: AC02-09CH11466; FG02-93ER54197

OSTI ID:: 1430535

Alternate ID(s):: OSTI ID: 1420217

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 25; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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