Comparison of plasma start-up with high Z and low Z first wall in WEST
The choice of first wall material is of paramount importance for the plasma start-up conditions in ITER and future fusion power plants. In this context, the present work focuses on the correlations between first wall impurity sources and total radiated power during plasma start-up in the tungsten (W...
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| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | Nuclear Fusion |
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| Online Access: | https://doi.org/10.1088/1741-4326/adaecf |
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| author | C. Guillemaut K. Afonin G. Bodner J. Bucalossi Y. Corre P. Devynck A. Diallo M. Diez N. Fedorczak A. Gallo B. Guillermin V. Lapleigne R. Lunsford P. Maget J. Morales Ph. Moreau the WEST Team the EUROfusion Tokamak Exploitation Team |
| author_facet | C. Guillemaut K. Afonin G. Bodner J. Bucalossi Y. Corre P. Devynck A. Diallo M. Diez N. Fedorczak A. Gallo B. Guillermin V. Lapleigne R. Lunsford P. Maget J. Morales Ph. Moreau the WEST Team the EUROfusion Tokamak Exploitation Team |
| author_sort | C. Guillemaut |
| collection | DOAJ |
| description | The choice of first wall material is of paramount importance for the plasma start-up conditions in ITER and future fusion power plants. In this context, the present work focuses on the correlations between first wall impurity sources and total radiated power during plasma start-up in the tungsten (W) Environment in Steady-state Tokamak (WEST). The objective is to highlight experimental indications for a preferable combination of start-up plasma scenario and first wall materials. Until 2019, WEST featured a full high Z first wall with all limiters exposing only W surfaces to the plasma. To study the impact of a low Z first wall in WEST, boron nitride tiles were installed in the central part of the inner and outer limiters in 2020. Although visible spectroscopy and bolometry measurements show respectively a strong weakening of the WI line intensity on the limiters and a reduction of radiated power after the changeover, a degradation occurs with the accumulation of plasma exposure. In addition, the different plasma facing elements of the main chamber do not influence equally the radiated power during start-up. In both high Z and low Z environments, a clear non-linear dependence is found between the start-up radiated power and the outer limiter W impurity source. Since W seems to be the main cause for core radiation, correlation between outer limiter W sources and other impurity sources are investigated. Finally, analysis of the legacy of B powder drops on a number of start-up plasmas suggests that it is less effective at reducing radiated power when the first wall is covered with W. |
| format | Article |
| id | doaj-art-d5b15f8b233a4a86ad6c3d29189e532d |
| institution | Kabale University |
| issn | 0029-5515 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Nuclear Fusion |
| spelling | doaj-art-d5b15f8b233a4a86ad6c3d29189e532d2025-02-10T09:04:19ZengIOP PublishingNuclear Fusion0029-55152025-01-0165303600710.1088/1741-4326/adaecfComparison of plasma start-up with high Z and low Z first wall in WESTC. Guillemaut0K. Afonin1https://orcid.org/0000-0002-5479-2897G. Bodner2https://orcid.org/0000-0003-2497-9172J. Bucalossi3Y. Corre4https://orcid.org/0000-0002-6566-6116P. Devynck5https://orcid.org/0000-0001-6752-9345A. Diallo6https://orcid.org/0000-0002-0706-060XM. Diez7N. Fedorczak8A. Gallo9https://orcid.org/0000-0002-7472-7830B. Guillermin10V. Lapleigne11R. Lunsford12https://orcid.org/0000-0003-3588-6801P. Maget13https://orcid.org/0000-0002-8746-8102J. Morales14https://orcid.org/0000-0002-3140-0504Ph. Moreau15the WEST Teamthe EUROfusion Tokamak Exploitation TeamCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FranceCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FrancePrinceton Plasma Physics Laboratory , Princeton, NJ, United States of America; General Atomics , San Diego, CA, United States of AmericaCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FranceCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FranceCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FrancePrinceton Plasma Physics Laboratory , Princeton, NJ, United States of AmericaCEA, 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, FrancePrinceton Plasma Physics Laboratory , Princeton, NJ, United States of AmericaCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FranceCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FranceCEA, IRFM , F-13108 Saint-Paul-Lez-Durance, FranceThe choice of first wall material is of paramount importance for the plasma start-up conditions in ITER and future fusion power plants. In this context, the present work focuses on the correlations between first wall impurity sources and total radiated power during plasma start-up in the tungsten (W) Environment in Steady-state Tokamak (WEST). The objective is to highlight experimental indications for a preferable combination of start-up plasma scenario and first wall materials. Until 2019, WEST featured a full high Z first wall with all limiters exposing only W surfaces to the plasma. To study the impact of a low Z first wall in WEST, boron nitride tiles were installed in the central part of the inner and outer limiters in 2020. Although visible spectroscopy and bolometry measurements show respectively a strong weakening of the WI line intensity on the limiters and a reduction of radiated power after the changeover, a degradation occurs with the accumulation of plasma exposure. In addition, the different plasma facing elements of the main chamber do not influence equally the radiated power during start-up. In both high Z and low Z environments, a clear non-linear dependence is found between the start-up radiated power and the outer limiter W impurity source. Since W seems to be the main cause for core radiation, correlation between outer limiter W sources and other impurity sources are investigated. Finally, analysis of the legacy of B powder drops on a number of start-up plasmas suggests that it is less effective at reducing radiated power when the first wall is covered with W.https://doi.org/10.1088/1741-4326/adaecfnuclear fusionplasma surface interactionvisible spectroscopyplasma start-upboronnitrogen |
| spellingShingle | C. Guillemaut K. Afonin G. Bodner J. Bucalossi Y. Corre P. Devynck A. Diallo M. Diez N. Fedorczak A. Gallo B. Guillermin V. Lapleigne R. Lunsford P. Maget J. Morales Ph. Moreau the WEST Team the EUROfusion Tokamak Exploitation Team Comparison of plasma start-up with high Z and low Z first wall in WEST Nuclear Fusion nuclear fusion plasma surface interaction visible spectroscopy plasma start-up boron nitrogen |
| title | Comparison of plasma start-up with high Z and low Z first wall in WEST |
| title_full | Comparison of plasma start-up with high Z and low Z first wall in WEST |
| title_fullStr | Comparison of plasma start-up with high Z and low Z first wall in WEST |
| title_full_unstemmed | Comparison of plasma start-up with high Z and low Z first wall in WEST |
| title_short | Comparison of plasma start-up with high Z and low Z first wall in WEST |
| title_sort | comparison of plasma start up with high z and low z first wall in west |
| topic | nuclear fusion plasma surface interaction visible spectroscopy plasma start-up boron nitrogen |
| url | https://doi.org/10.1088/1741-4326/adaecf |
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