Impact of the new TCV baffled divertor upgrade on pedestal structure and performance
A new set of carbon tiles, neutral beam heating optics and gas baffles were installed on TCV during the baffled divertor upgrade in early 2019. The installation of the baffles allows a deconvolution of the roles of main chamber and divertor neutral pressure on the H-mode pedestal structure. This phy...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2021-03-01
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| Series: | Nuclear Materials and Energy |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179121000259 |
| _version_ | 1818461204605042688 |
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| author | U.A. Sheikh M. Dunne L. Frassinetti B. Labit P. Blanchard B.P. Duval O. Février D. Galassi A. Merle H. Reimerdes C. Theiler |
| author_facet | U.A. Sheikh M. Dunne L. Frassinetti B. Labit P. Blanchard B.P. Duval O. Février D. Galassi A. Merle H. Reimerdes C. Theiler |
| author_sort | U.A. Sheikh |
| collection | DOAJ |
| description | A new set of carbon tiles, neutral beam heating optics and gas baffles were installed on TCV during the baffled divertor upgrade in early 2019. The installation of the baffles allows a deconvolution of the roles of main chamber and divertor neutral pressure on the H-mode pedestal structure. This physical barrier allows relatively high neutral pressures to be constrained to the divertor, thus preventing neutrals from entering the main chamber and potentially degrading core confinement. This study presents the experimentally measured and modelled pedestal heights and structure for a series of H-mode discharges prior to and after this upgrade.Increased pedestal performance at high divertor neutral pressure was observed after the baffled divertor upgrade. This was consistent across all triangularities and outer target locations investigated and is attributed to higher pedestal top temperatures being maintained at high gas injection rates. ASTRA simulations indicated beam heating power coupled to the plasma did not significantly vary after the baffled divertor upgrade or as a function of divertor neutral gas pressure. Analysis of the pedestal structure exposed a strong correlation between pedestal performance and the density pedestal position prior to and after the baffled divertor upgrade. The baffled divertor upgrade limited the outward shift of the density pedestal, thus maintaining higher pedestal performance at high divertor neutral pressures. Stability analysis indicated the majority of discharges studied were within 25% of the stability boundary. No correlation was found between the distance from the stability boundary and pedestal performance or structure. Comparison with the EPED1 model indicated that TCV discharges do not have a fixed dependence between pedestal βθand pedestal width. A large variation in the EPED1 relating parameter was observed and found to vary with the density pedestal position. |
| first_indexed | 2024-12-14T23:42:26Z |
| format | Article |
| id | doaj.art-2ba6c3dd0fdd493386fd9229a5c01169 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-12-14T23:42:26Z |
| publishDate | 2021-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-2ba6c3dd0fdd493386fd9229a5c011692022-12-21T22:43:29ZengElsevierNuclear Materials and Energy2352-17912021-03-0126100933Impact of the new TCV baffled divertor upgrade on pedestal structure and performanceU.A. Sheikh0M. Dunne1L. Frassinetti2B. Labit3P. Blanchard4B.P. Duval5O. Février6D. Galassi7A. Merle8H. Reimerdes9C. Theiler10École Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, Switzerland; Corresponding author.Max-Planck-Institut fur Plasmaphysik, 85748 Garching b. Munchen, GermanyKTH Royal Institute of Technology, Stockholm, SwedenÉcole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, SwitzerlandMax-Planck-Institut fur Plasmaphysik, 85748 Garching b. Munchen, GermanyÉcole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, SwitzerlandÉcole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, SwitzerlandÉcole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, SwitzerlandÉcole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, SwitzerlandÉcole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, SwitzerlandÉcole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015, Lausanne, SwitzerlandA new set of carbon tiles, neutral beam heating optics and gas baffles were installed on TCV during the baffled divertor upgrade in early 2019. The installation of the baffles allows a deconvolution of the roles of main chamber and divertor neutral pressure on the H-mode pedestal structure. This physical barrier allows relatively high neutral pressures to be constrained to the divertor, thus preventing neutrals from entering the main chamber and potentially degrading core confinement. This study presents the experimentally measured and modelled pedestal heights and structure for a series of H-mode discharges prior to and after this upgrade.Increased pedestal performance at high divertor neutral pressure was observed after the baffled divertor upgrade. This was consistent across all triangularities and outer target locations investigated and is attributed to higher pedestal top temperatures being maintained at high gas injection rates. ASTRA simulations indicated beam heating power coupled to the plasma did not significantly vary after the baffled divertor upgrade or as a function of divertor neutral gas pressure. Analysis of the pedestal structure exposed a strong correlation between pedestal performance and the density pedestal position prior to and after the baffled divertor upgrade. The baffled divertor upgrade limited the outward shift of the density pedestal, thus maintaining higher pedestal performance at high divertor neutral pressures. Stability analysis indicated the majority of discharges studied were within 25% of the stability boundary. No correlation was found between the distance from the stability boundary and pedestal performance or structure. Comparison with the EPED1 model indicated that TCV discharges do not have a fixed dependence between pedestal βθand pedestal width. A large variation in the EPED1 relating parameter was observed and found to vary with the density pedestal position.http://www.sciencedirect.com/science/article/pii/S2352179121000259PedestalBafflesTCV |
| spellingShingle | U.A. Sheikh M. Dunne L. Frassinetti B. Labit P. Blanchard B.P. Duval O. Février D. Galassi A. Merle H. Reimerdes C. Theiler Impact of the new TCV baffled divertor upgrade on pedestal structure and performance Nuclear Materials and Energy Pedestal Baffles TCV |
| title | Impact of the new TCV baffled divertor upgrade on pedestal structure and performance |
| title_full | Impact of the new TCV baffled divertor upgrade on pedestal structure and performance |
| title_fullStr | Impact of the new TCV baffled divertor upgrade on pedestal structure and performance |
| title_full_unstemmed | Impact of the new TCV baffled divertor upgrade on pedestal structure and performance |
| title_short | Impact of the new TCV baffled divertor upgrade on pedestal structure and performance |
| title_sort | impact of the new tcv baffled divertor upgrade on pedestal structure and performance |
| topic | Pedestal Baffles TCV |
| url | http://www.sciencedirect.com/science/article/pii/S2352179121000259 |
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