Numerical modelling of the impact of leakage under divertor baffle in WEST
In WEST experimental campaign C5, the divertor pumping capability has been improved by sealing the space between the divertor outer baffle and the vacuum vessel. It is expected that the degree of baffle leakage influences the transport of neutral particles inside the main chamber, which affects the...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2022-10-01
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| Series: | Nuclear Materials and Energy |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179122001831 |
| _version_ | 1798016132303552512 |
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| author | H. Yang G. Ciraolo J. Bucalossi H. Bufferand N. Fedorczak P. Tamain G. Falchetto N. Rivals J.P. Gunn Y. Marandet B. Pégourié S. Vartanian |
| author_facet | H. Yang G. Ciraolo J. Bucalossi H. Bufferand N. Fedorczak P. Tamain G. Falchetto N. Rivals J.P. Gunn Y. Marandet B. Pégourié S. Vartanian |
| author_sort | H. Yang |
| collection | DOAJ |
| description | In WEST experimental campaign C5, the divertor pumping capability has been improved by sealing the space between the divertor outer baffle and the vacuum vessel. It is expected that the degree of baffle leakage influences the transport of neutral particles inside the main chamber, which affects the detachment onset. Knowing the exact impacts of leakage and understanding the physical processes behind it are helpful for the study and control of plasma detachment. We investigate the impact of leakage by performing transport simulations through SOLEDGE-EIRENE code considering several cases with different leakage levels. Starting from the basic simulation case, non-constant radial transport coefficients obtained by the feedback control method are applied to achieve a better match with the experimental one (#54903) in L-mode. Based on the basic case, the evolution of plasma regimes from sheath limited regime to detached one in different wall geometries has been studied by ramping the upstream density. The numerical results show that the cases with closed or reduced leakage under the baffle have better performance in trapping the neutral particles and higher neutral pressure near the baffle. The neutral compression ratio is increased by a factor up to 4, leading to more significant momentum and power dissipation in the divertor, thus lowering the detachment threshold in ne,sep by up to 16%. At the same time, a much higher gas puff rate by a factor up to 22 is needed to maintain an equivalent ne,sep level in the case without or reduced leakage. For all the cases here, there exist characteristic parameters on which the baffle closure has no obvious influence on their value when plasma starts to detach. The evolution of radiator height as a function of target temperature shows no sensitivity to the leakage, which gives some insight into the stable detachment control strategy in the future. Finally, simulation results are compared with available neutral pressure measurements from WEST campaigns to verify the predictions from the simulation. |
| first_indexed | 2024-04-11T15:45:55Z |
| format | Article |
| id | doaj.art-a981e0b26c014a99b738703c42d57d99 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-04-11T15:45:55Z |
| publishDate | 2022-10-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-a981e0b26c014a99b738703c42d57d992022-12-22T04:15:31ZengElsevierNuclear Materials and Energy2352-17912022-10-0133101302Numerical modelling of the impact of leakage under divertor baffle in WESTH. Yang0G. Ciraolo1J. Bucalossi2H. Bufferand3N. Fedorczak4P. Tamain5G. Falchetto6N. Rivals7J.P. Gunn8Y. Marandet9B. Pégourié10S. Vartanian11CEA, IRFM, F-13108 Saint Paul-lez-Durance, France; Corresponding author.CEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceAix Marseille University, CNRS, PIIM, Marseille, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceCEA, IRFM, F-13108 Saint Paul-lez-Durance, FranceIn WEST experimental campaign C5, the divertor pumping capability has been improved by sealing the space between the divertor outer baffle and the vacuum vessel. It is expected that the degree of baffle leakage influences the transport of neutral particles inside the main chamber, which affects the detachment onset. Knowing the exact impacts of leakage and understanding the physical processes behind it are helpful for the study and control of plasma detachment. We investigate the impact of leakage by performing transport simulations through SOLEDGE-EIRENE code considering several cases with different leakage levels. Starting from the basic simulation case, non-constant radial transport coefficients obtained by the feedback control method are applied to achieve a better match with the experimental one (#54903) in L-mode. Based on the basic case, the evolution of plasma regimes from sheath limited regime to detached one in different wall geometries has been studied by ramping the upstream density. The numerical results show that the cases with closed or reduced leakage under the baffle have better performance in trapping the neutral particles and higher neutral pressure near the baffle. The neutral compression ratio is increased by a factor up to 4, leading to more significant momentum and power dissipation in the divertor, thus lowering the detachment threshold in ne,sep by up to 16%. At the same time, a much higher gas puff rate by a factor up to 22 is needed to maintain an equivalent ne,sep level in the case without or reduced leakage. For all the cases here, there exist characteristic parameters on which the baffle closure has no obvious influence on their value when plasma starts to detach. The evolution of radiator height as a function of target temperature shows no sensitivity to the leakage, which gives some insight into the stable detachment control strategy in the future. Finally, simulation results are compared with available neutral pressure measurements from WEST campaigns to verify the predictions from the simulation.http://www.sciencedirect.com/science/article/pii/S2352179122001831DetachmentSOLDivertorBaffle closureLeakage effectNumerical modelling |
| spellingShingle | H. Yang G. Ciraolo J. Bucalossi H. Bufferand N. Fedorczak P. Tamain G. Falchetto N. Rivals J.P. Gunn Y. Marandet B. Pégourié S. Vartanian Numerical modelling of the impact of leakage under divertor baffle in WEST Nuclear Materials and Energy Detachment SOL Divertor Baffle closure Leakage effect Numerical modelling |
| title | Numerical modelling of the impact of leakage under divertor baffle in WEST |
| title_full | Numerical modelling of the impact of leakage under divertor baffle in WEST |
| title_fullStr | Numerical modelling of the impact of leakage under divertor baffle in WEST |
| title_full_unstemmed | Numerical modelling of the impact of leakage under divertor baffle in WEST |
| title_short | Numerical modelling of the impact of leakage under divertor baffle in WEST |
| title_sort | numerical modelling of the impact of leakage under divertor baffle in west |
| topic | Detachment SOL Divertor Baffle closure Leakage effect Numerical modelling |
| url | http://www.sciencedirect.com/science/article/pii/S2352179122001831 |
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