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

Abstract

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 measuredmore » 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.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [2];  [1];  [2];  [2];  [2];  [1];  [2];  [2]; ORCiD logo [1];  [2];  [1];  [2];  [2]; ORCiD logo [2]; ORCiD logo [4];  [5];  [1] more »;  [2];  [4];  [6]; ORCiD logo [1];  [2];  [7];  [2];  [6];  [2];  [2];  [3];  [2];  [2]; ORCiD logo [2]; ORCiD logo [7];  [2] « less
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Max-Planck-Inst. fur Plasmaphysik, Greifswald (Germany)
  3. Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Lab. Nacional de Fusion
  4. Forschungszentrum Julich (Germany). Inst. fur Energie- und Klimaforschung (IEK)
  5. Univ. of Maryland, College Park, MD (United States)
  6. Auburn Univ., AL (United States)
  7. National Inst. for Fusion Science, Toki (Japan); Graduate Univ. for Advanced Studies (SOKENDAI), Toki (Japan)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE; Euratom Research and Training Programme
Contributing Org.:
W7-X Team
OSTI Identifier:
1430535
Alternate Identifier(s):
OSTI ID: 1420217
Grant/Contract Number:  
AC02-09CH11466; FG02-93ER54197; 633053
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 2; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

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., and Zhang, D. Core radial electric field and transport in Wendelstein 7-X plasmas. United States: N. p., 2018. Web. doi:10.1063/1.4999842.
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. Core radial electric field and transport in Wendelstein 7-X plasmas. United States. doi:10.1063/1.4999842.
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., and Zhang, D. Mon . "Core radial electric field and transport in Wendelstein 7-X plasmas". United States. doi:10.1063/1.4999842. https://www.osti.gov/servlets/purl/1430535.
@article{osti_1430535,
title = {Core radial electric field and transport in Wendelstein 7-X plasmas},
author = {Pablant, N. A. and Langenberg, A. and Alonso, A. and Beidler, C. D. and Bitter, M. and Bozhenkov, S. and Burhenn, R. and Beurskens, M. and Delgado-Aparicio, L. and Dinklage, A. and Fuchert, G. and Gates, D. and Geiger, J. and Hill, K. W. and Hofel, U. and Hirsch, M. and Knauer, J. and Kramer-Flecken, A. and Landreman, M. and Lazerson, S. and MaaBberg, H. and Marchuk, O. and Massidda, S. and Neilson, G. H. and Pasch, E. and Satake, S. and Svennson, J. and Traverso, P. and Turkin, Y. and Valson, P. and Velasco, J. L. and Weir, G. and Windisch, T. and Wolf, R. C. and Yokoyama, M. and Zhang, D.},
abstractNote = {The results from the investigation of neoclassical core transport and the role of the radial electric field profile (Er) in the first operational phase of the Wendelstein 7-X (W7-X) stellarator are presented. In stellarator plasmas, the details of the Er 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 (ΔEr ~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 Er 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.},
doi = {10.1063/1.4999842},
journal = {Physics of Plasmas},
number = 2,
volume = 25,
place = {United States},
year = {2018},
month = {2}
}

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Figures / Tables:

FIG. 1. FIG. 1. : Viewing geometry of the the XICS diagnostic on W7-X.

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    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.