Access to edge scenarios for testing a scraper element in early operation phases of Wendelstein 7-X
Abstract
The edge topology of magnetic fusion devices is decisive for the control of the plasma exhaust. In Wendelstein 7-X, the island divertor concept will be used, for which the edge topology can change significantly as the internal currents in a plasma discharge evolve towards steady-state. Consequently, the device has been optimized to minimize such internal currents, in particular the bootstrap current [1]. Nonetheless, there are predicted pulse scenarios where effects of the remaining internal currents could potentially lead to overload of plasma-facing components. These internal currents are predicted to evolve on long time scales (tens of seconds) so their effects on the edge topology and the divertor heat loads may not be experimentally accessible in the first years of W7-X operation, where only relatively short pulses are possible. However, we show here that for at least one important long-pulse divertor operation issue, relevant physics experiments can be performed already in short-pulse operation, through judicious adjustment of the edge topology by the use of the existing coil sets. The specific issue studied here is a potential overload of the divertor element edges. This overload might be mitigated by the installation of an extra set of plasma-facing components, so-called scraper elements, asmore »
- Authors:
-
- Max Planck Institute for Plasma Physics, Greifswald (Germany)
- Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Publication Date:
- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC)
- OSTI Identifier:
- 1265944
- Grant/Contract Number:
- AC05-00OR22725
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nuclear Fusion
- Additional Journal Information:
- Journal Volume: 56; Journal Issue: 2; Journal ID: ISSN 0029-5515
- Publisher:
- IOP Science
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
Holbe, H., Pedersen, T. Sunn, Geiger, J., Bozhenkov, S., Kornejew, P, Feng, Y., Lore, Jeremy D., Lumsdaine, Arnold, and Konig, R. Access to edge scenarios for testing a scraper element in early operation phases of Wendelstein 7-X. United States: N. p., 2016.
Web. doi:10.1088/0029-5515/56/2/026015.
Holbe, H., Pedersen, T. Sunn, Geiger, J., Bozhenkov, S., Kornejew, P, Feng, Y., Lore, Jeremy D., Lumsdaine, Arnold, & Konig, R. Access to edge scenarios for testing a scraper element in early operation phases of Wendelstein 7-X. United States. https://doi.org/10.1088/0029-5515/56/2/026015
Holbe, H., Pedersen, T. Sunn, Geiger, J., Bozhenkov, S., Kornejew, P, Feng, Y., Lore, Jeremy D., Lumsdaine, Arnold, and Konig, R. Fri .
"Access to edge scenarios for testing a scraper element in early operation phases of Wendelstein 7-X". United States. https://doi.org/10.1088/0029-5515/56/2/026015. https://www.osti.gov/servlets/purl/1265944.
@article{osti_1265944,
title = {Access to edge scenarios for testing a scraper element in early operation phases of Wendelstein 7-X},
author = {Holbe, H. and Pedersen, T. Sunn and Geiger, J. and Bozhenkov, S. and Kornejew, P and Feng, Y. and Lore, Jeremy D. and Lumsdaine, Arnold and Konig, R.},
abstractNote = {The edge topology of magnetic fusion devices is decisive for the control of the plasma exhaust. In Wendelstein 7-X, the island divertor concept will be used, for which the edge topology can change significantly as the internal currents in a plasma discharge evolve towards steady-state. Consequently, the device has been optimized to minimize such internal currents, in particular the bootstrap current [1]. Nonetheless, there are predicted pulse scenarios where effects of the remaining internal currents could potentially lead to overload of plasma-facing components. These internal currents are predicted to evolve on long time scales (tens of seconds) so their effects on the edge topology and the divertor heat loads may not be experimentally accessible in the first years of W7-X operation, where only relatively short pulses are possible. However, we show here that for at least one important long-pulse divertor operation issue, relevant physics experiments can be performed already in short-pulse operation, through judicious adjustment of the edge topology by the use of the existing coil sets. The specific issue studied here is a potential overload of the divertor element edges. This overload might be mitigated by the installation of an extra set of plasma-facing components, so-called scraper elements, as suggested in earlier publications. It is shown here that by a targeted control of edge topology, the effectiveness of such scraper elements can be tested already with uncooled test-scraper elements in short-pulse operation. Furthermore, this will allow an early and well-informed decision on whether long-pulse-capable (actively cooled) scraper elements should be built and installed.},
doi = {10.1088/0029-5515/56/2/026015},
journal = {Nuclear Fusion},
number = 2,
volume = 56,
place = {United States},
year = {Fri Jan 29 00:00:00 EST 2016},
month = {Fri Jan 29 00:00:00 EST 2016}
}
Web of Science
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