Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms
Assessing the performance of the ITER design for the tungsten (W) divertor Plasma Facing Units (PFUs) in a tokamak environment is a high priority issue to ensure efficient plasma operation. This paper reviews the most recent results derived from experiments and post-mortem analysis of the ITER-grade...
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| Language: | English |
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Elsevier
2023-12-01
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| Series: | Nuclear Materials and Energy |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179123001850 |
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| author | Y. Corre M-H. Aumeunier A. Durif J. Gaspar K. Krieger T. Loewenhoff M. Richou S. Ratynskaia Q. Tichit Y. Anquetin R. Dejarnac M. Diez L. Dubus M. Firdaouss J. Gerardin A.. Grosjean J.P. Gunn T. Loarer P. Maget C. Martin K. Paschalidis E. Tsitrone M. Wirtz |
| author_facet | Y. Corre M-H. Aumeunier A. Durif J. Gaspar K. Krieger T. Loewenhoff M. Richou S. Ratynskaia Q. Tichit Y. Anquetin R. Dejarnac M. Diez L. Dubus M. Firdaouss J. Gerardin A.. Grosjean J.P. Gunn T. Loarer P. Maget C. Martin K. Paschalidis E. Tsitrone M. Wirtz |
| author_sort | Y. Corre |
| collection | DOAJ |
| description | Assessing the performance of the ITER design for the tungsten (W) divertor Plasma Facing Units (PFUs) in a tokamak environment is a high priority issue to ensure efficient plasma operation. This paper reviews the most recent results derived from experiments and post-mortem analysis of the ITER-grade PFUs exposed in the WEST tokamak and the associated modelling, with a focus on understanding heat loading and damage evolution. Several shaping options, sharp or chamfered leading edge (LE), unshaped or shaped blocks with a toroidal bevel as foreseen in ITER, were investigated, under steady state heat fluxes of up to 120 MW⋅m−2 and 6 MW⋅m−2 on the sharp LE and top surface of the block, respectively. A very high spatial resolution (VHR) infrared (IR) camera (0.1 mm/pixel) was used to derive the temporal and surface distribution of the temperature and heat load on the castellated tungsten blocks for different geometric alignment and plasma conditions. Photonic modelling was required to reproduce the IR measurements in particular in the toroidal and poloidal gaps of the mono-block (MB) stacks where high apparent temperatures are observed. Specular reflection is found to be the dominant emitter in these parts of the blocks. W-cracking was observed on the leading edge of the blocks already within the first phase of plasma operation, during which the divertor was equipped with unshaped PFUs, including some intentionally misaligned blocks. Numerical analysis taking into account softening processes and mechanical stresses, revealed brittle failure due to transients as the dominant failure mechanisms. Ductile failure was observed in one particular block used for the melting experiment, therefore under extremely high steady state heat load conditions. W-melting achieved on actively cooled PFU exhibits specific features: shallow melting and slow melt displacement. Plasma exposure of pre-damaged PFUs at various damage levels (crack network and melted droplets) was carried out under high heat load conditions with several hours of cumulated plasma duration. IR data and preliminary surface analyses show no evidence of significant degradation damage progression under these conditions. |
| first_indexed | 2024-03-09T02:14:51Z |
| format | Article |
| id | doaj.art-8daa185bfc6d47299e72398796f748a1 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-03-09T02:14:51Z |
| publishDate | 2023-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-8daa185bfc6d47299e72398796f748a12023-12-07T05:28:59ZengElsevierNuclear Materials and Energy2352-17912023-12-0137101546Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanismsY. Corre0M-H. Aumeunier1A. Durif2J. Gaspar3K. Krieger4T. Loewenhoff5M. Richou6S. Ratynskaia7Q. Tichit8Y. Anquetin9R. Dejarnac10M. Diez11L. Dubus12M. Firdaouss13J. Gerardin14A.. Grosjean15J.P. Gunn16T. Loarer17P. Maget18C. Martin19K. Paschalidis20E. Tsitrone21M. Wirtz22CEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, France; Corresponding authors at: CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.CEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceAix Marseille Univ, CNRS, IUSTI, Marseille, FranceMax-Planck-Institut für Plasmaphysik, 85748 Garching b. München, GermanyForschungszentrum Jülich GmbH, Institut für Energie und Klimaforschung, 52425 Jülich, GermanyCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceSpace and Plasma Physics, KTH Royal Institute of Technology, SE-10044, Stockholm, SwedenCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceAix Marseille Univ, CNRS, IUSTI, Marseille, FranceInstitute of Plasma Physics, Czech Academy of Sciences, 182 00 Prague, Czech RepublicCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceAix Marseille Univ, PIIM UMR 7345, F-13397 Marseille, FranceSpace and Plasma Physics, KTH Royal Institute of Technology, SE-10044, Stockholm, SwedenCEA, Institute for Research on Fusion by Magnetic confinement, 13108 St-Paul-Lez-Durance, FranceForschungszentrum Jülich GmbH, Institut für Energie und Klimaforschung, 52425 Jülich, GermanyAssessing the performance of the ITER design for the tungsten (W) divertor Plasma Facing Units (PFUs) in a tokamak environment is a high priority issue to ensure efficient plasma operation. This paper reviews the most recent results derived from experiments and post-mortem analysis of the ITER-grade PFUs exposed in the WEST tokamak and the associated modelling, with a focus on understanding heat loading and damage evolution. Several shaping options, sharp or chamfered leading edge (LE), unshaped or shaped blocks with a toroidal bevel as foreseen in ITER, were investigated, under steady state heat fluxes of up to 120 MW⋅m−2 and 6 MW⋅m−2 on the sharp LE and top surface of the block, respectively. A very high spatial resolution (VHR) infrared (IR) camera (0.1 mm/pixel) was used to derive the temporal and surface distribution of the temperature and heat load on the castellated tungsten blocks for different geometric alignment and plasma conditions. Photonic modelling was required to reproduce the IR measurements in particular in the toroidal and poloidal gaps of the mono-block (MB) stacks where high apparent temperatures are observed. Specular reflection is found to be the dominant emitter in these parts of the blocks. W-cracking was observed on the leading edge of the blocks already within the first phase of plasma operation, during which the divertor was equipped with unshaped PFUs, including some intentionally misaligned blocks. Numerical analysis taking into account softening processes and mechanical stresses, revealed brittle failure due to transients as the dominant failure mechanisms. Ductile failure was observed in one particular block used for the melting experiment, therefore under extremely high steady state heat load conditions. W-melting achieved on actively cooled PFU exhibits specific features: shallow melting and slow melt displacement. Plasma exposure of pre-damaged PFUs at various damage levels (crack network and melted droplets) was carried out under high heat load conditions with several hours of cumulated plasma duration. IR data and preliminary surface analyses show no evidence of significant degradation damage progression under these conditions.http://www.sciencedirect.com/science/article/pii/S2352179123001850Tungsten crackingMeltingPlasma Facing UnitHeat flux calculationIR thermography |
| spellingShingle | Y. Corre M-H. Aumeunier A. Durif J. Gaspar K. Krieger T. Loewenhoff M. Richou S. Ratynskaia Q. Tichit Y. Anquetin R. Dejarnac M. Diez L. Dubus M. Firdaouss J. Gerardin A.. Grosjean J.P. Gunn T. Loarer P. Maget C. Martin K. Paschalidis E. Tsitrone M. Wirtz Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms Nuclear Materials and Energy Tungsten cracking Melting Plasma Facing Unit Heat flux calculation IR thermography |
| title | Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms |
| title_full | Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms |
| title_fullStr | Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms |
| title_full_unstemmed | Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms |
| title_short | Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms |
| title_sort | testing of iter grade plasma facing units in the west tokamak progress in understanding heat loading and damage mechanisms |
| topic | Tungsten cracking Melting Plasma Facing Unit Heat flux calculation IR thermography |
| url | http://www.sciencedirect.com/science/article/pii/S2352179123001850 |
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