Effects of divertor geometry on H-mode pedestal structure in attached and detached plasmas in the DIII-D tokamak [Effects of divertor geometry on H-mode pedestal structure near divertor detachment in the DIII-D tokamak]
Abstract
Dedicated experiments have been performed in the DIII-D tokamak to assess the influence of divertor geometry on the H-mode pedestal structure. It has been found that in both attached and detached plasmas, compared to the open divertor, the more closed divertor traps more neutrals in the divertor region, leading to lower pedestal fueling and thus results in lower density and higher temperature at the pedestal top. In addition, approaching divertor detachment by increasing the gas-puffing rate, for different divertor geometries, the pedestal width exhibits different trends. In the attached plasma, the pedestal width agrees well with the theoretical and empirical pedestal-poloidal-beta scaling. However, during divertor detachment, in the open divertor the pedestal width is significantly reduced. In contrast, for detached plasmas with the more closed divertor, the pedestal is significantly wider, by up to 50% compared to the theoretical scaling. Moreover, near divertor detachment, the open diverted plasma exhibits a more aligned density and temperature pedestal profile, while in the closed divertor the detachment results in a relative shift (up to 50% of the pedestal width) between the density and temperature pedestal profiles. Such changes in the pedestal structure, coupled with reduced pedestal fueling, allow for the achievement of divertormore »
- Authors:
-
[2];
- Oak Ridge Associated Univ., Oak Ridge, TN (United States)
- General Atomics, San Diego, CA (United States)
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Univ. of Wisconsin-Madison, Madison, WI (United States)
- Publication Date:
- Research Org.:
- General Atomics, San Diego, CA (United States)
- Sponsoring Org.:
- USDOE Office of Nuclear Energy (NE)
- Contributing Org.:
- The DIII-D group
- OSTI Identifier:
- 1461182
- Grant/Contract Number:
- FC02-04ER54698
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nuclear Fusion
- Additional Journal Information:
- Journal Volume: 58; Journal Issue: 9; Journal ID: ISSN 0029-5515
- Publisher:
- IOP Science
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; H-mode pedestal; divertor geometry; divertor detachment
Citation Formats
Wang, H. Q., Guo, H. Y., Leonard, A. W., Moser, A. L., Osborne, T. H., Snyder, P. B., Belli, E., Groebner, R. J., Thomas, D. M., Watkins, J. G., and Yan, Z. Effects of divertor geometry on H-mode pedestal structure in attached and detached plasmas in the DIII-D tokamak [Effects of divertor geometry on H-mode pedestal structure near divertor detachment in the DIII-D tokamak]. United States: N. p., 2018.
Web. doi:10.1088/1741-4326/aacbde.
Wang, H. Q., Guo, H. Y., Leonard, A. W., Moser, A. L., Osborne, T. H., Snyder, P. B., Belli, E., Groebner, R. J., Thomas, D. M., Watkins, J. G., & Yan, Z. Effects of divertor geometry on H-mode pedestal structure in attached and detached plasmas in the DIII-D tokamak [Effects of divertor geometry on H-mode pedestal structure near divertor detachment in the DIII-D tokamak]. United States. https://doi.org/10.1088/1741-4326/aacbde
Wang, H. Q., Guo, H. Y., Leonard, A. W., Moser, A. L., Osborne, T. H., Snyder, P. B., Belli, E., Groebner, R. J., Thomas, D. M., Watkins, J. G., and Yan, Z. Thu .
"Effects of divertor geometry on H-mode pedestal structure in attached and detached plasmas in the DIII-D tokamak [Effects of divertor geometry on H-mode pedestal structure near divertor detachment in the DIII-D tokamak]". United States. https://doi.org/10.1088/1741-4326/aacbde. https://www.osti.gov/servlets/purl/1461182.
@article{osti_1461182,
title = {Effects of divertor geometry on H-mode pedestal structure in attached and detached plasmas in the DIII-D tokamak [Effects of divertor geometry on H-mode pedestal structure near divertor detachment in the DIII-D tokamak]},
author = {Wang, H. Q. and Guo, H. Y. and Leonard, A. W. and Moser, A. L. and Osborne, T. H. and Snyder, P. B. and Belli, E. and Groebner, R. J. and Thomas, D. M. and Watkins, J. G. and Yan, Z.},
abstractNote = {Dedicated experiments have been performed in the DIII-D tokamak to assess the influence of divertor geometry on the H-mode pedestal structure. It has been found that in both attached and detached plasmas, compared to the open divertor, the more closed divertor traps more neutrals in the divertor region, leading to lower pedestal fueling and thus results in lower density and higher temperature at the pedestal top. In addition, approaching divertor detachment by increasing the gas-puffing rate, for different divertor geometries, the pedestal width exhibits different trends. In the attached plasma, the pedestal width agrees well with the theoretical and empirical pedestal-poloidal-beta scaling. However, during divertor detachment, in the open divertor the pedestal width is significantly reduced. In contrast, for detached plasmas with the more closed divertor, the pedestal is significantly wider, by up to 50% compared to the theoretical scaling. Moreover, near divertor detachment, the open diverted plasma exhibits a more aligned density and temperature pedestal profile, while in the closed divertor the detachment results in a relative shift (up to 50% of the pedestal width) between the density and temperature pedestal profiles. Such changes in the pedestal structure, coupled with reduced pedestal fueling, allow for the achievement of divertor detachment while retaining high pedestal performance with the more closed divertor.},
doi = {10.1088/1741-4326/aacbde},
journal = {Nuclear Fusion},
number = 9,
volume = 58,
place = {United States},
year = {Thu Jul 05 00:00:00 EDT 2018},
month = {Thu Jul 05 00:00:00 EDT 2018}
}
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