Nuclear Materials and Energy最新文献

{"title":"Strength of a circumferential W/Cu/CuCrZr joint of ITER monoblock","authors":"K. Poleshchuk ,&nbsp;D. Terentyev ,&nbsp;F. Crea ,&nbsp;P. Gavila ,&nbsp;S. Roccella ,&nbsp;K. Verbeken","doi":"10.1016/j.nme.2025.101947","DOIUrl":"10.1016/j.nme.2025.101947","url":null,"abstract":"<div><div>A newly developed methodology for testing ITER monoblock was applied for the first time to measure the strength of a circumferential W/Cu/CuCrZr joint. An innovative anchor-shape configuration was used to machine tensile samples using ITER-specification W/Cu monoblocks, on which ITER-specification CuCrZr pipe was attached using hot radial pressing.</div><div>This contribution presents the results of mechanical testing and microstructural investigations of the abovementioned W/Cu/CuCrZr joints conducted at room temperature, as well as at the ITER operational conditions. It is found that depending on the test temperature, the fracture occurs in different locations corresponding to different damage modes. In some cases, the obtained ultimate tensile strength can be directly associated with the joint strength. However, the methodology emphasises the importance of correlating fracture location and detailed microstructural analysis of the fracture surface with the tensile test results. The findings reveal the dependencies of the joint strength and fracture mode on temperature, with a transition in failure modes observed at elevated temperatures. The results presented in this article are important for the interpretation of the effect of future neutron irradiation campaigns on W/Cu/CuCrZr joints.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101947"},"PeriodicalIF":2.3,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144138676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SLM-printed EUROFER steel for fusion applications","authors":"Ramil Gaisin,&nbsp;Carsten Bonnekoh,&nbsp;Simon Bonk,&nbsp;Heiko Neuberger,&nbsp;Vladimir Chakin,&nbsp;Michael Rieth","doi":"10.1016/j.nme.2025.101951","DOIUrl":"10.1016/j.nme.2025.101951","url":null,"abstract":"<div><div>This study investigates selective laser melting (SLM) of atomized EUROFER97 powder for fusion applications, focusing on two fabrications and their resulting microstructure, tensile properties, impact toughness, and leak-tightness. Optimized powder preparation improved chemical composition and grain size after heat treatment, enhancing Charpy impact toughness with an upper shelf energy surpassing the EUROFER97 standard and a lower ductile-to-brittle transition temperature (−120 °C vs. −100 °C). Tensile properties, including yield and ultimate strength and elongation, were similar to the EUROFER97 reference material.</div><div>SLM-printed capsules demonstrated excellent leak-tightness, with helium leak rates well below ITER requirements, and burst tests confirmed ultimate strengths exceeding 700 MPa. These findings showcase potential of SLM for creating complex components for fusion reactor blankets with tailored mechanical properties.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101951"},"PeriodicalIF":2.3,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144115929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of W and Mo on the formation of early stage α’ solute clusters in ion-irradiated Fe-Cr-X (X = W/Mo) alloys","authors":"Rong Hu ,&nbsp;Yuhang Zhu ,&nbsp;Meiqing Chen ,&nbsp;Jing Xue","doi":"10.1016/j.nme.2025.101950","DOIUrl":"10.1016/j.nme.2025.101950","url":null,"abstract":"<div><div>Reduced activation ferritic-martensitic (RAFM) steels are known to suffer from 475 °C embrittlement, which is associated with the formation of Cr-enriched α’ phase, while dislocation loops also contribute to radiation hardening. The precipitation behavior in RAFM steels is highly complex, involving the formation of various types of precipitates as well as intricate interactions between different alloying elements. To date, only a limited number of studies have investigated the effects of minor alloying elements, such as Ni, Si, P, C and Al, under irradiation conditions. To enhance understanding of α’ phase formation in RAFM steels, this study conducted detailed experiments using Atom Probe Tomography (APT) on Fe-9Cr, Fe-9Cr-0.5 W and Fe-9Cr-0.5Mo alloys under self-ion irradiation to examine the effects of W and Mo additions. Ion irradiation was performed using sequential energies of 0.5 MeV, 1 MeV, and 2 MeV to achieve target maximum damage levels of 5 dpa and 10 dpa at 350 °C. Cr-enriched clusters were identified in these ion-irradiated samples. It was observed that W strongly suppresses the formation and evolution of Cr-enriched clusters due to its strong binding with vacancies, which reduces Cr diffusion. In contrast, Mo appears to promote the formation of Cr-enriched clusters and facilitates the growth of large clusters, possibly due to the positive interaction between Mo and Cr atoms.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101950"},"PeriodicalIF":2.3,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved liquid lithium surfaces in the Lithium Tokamak Experiment-β","authors":"D.P. Boyle ,&nbsp;A. Maan ,&nbsp;R. Majeski ,&nbsp;E. Ostrowski ,&nbsp;S. Abe ,&nbsp;S. Banerjee ,&nbsp;W. Capecchi ,&nbsp;D.B. Elliott ,&nbsp;C. Hansen ,&nbsp;E. Jung ,&nbsp;P.E. Hughes ,&nbsp;S. Kubota ,&nbsp;M. Lampert ,&nbsp;R. Maingi ,&nbsp;A.G. McLean ,&nbsp;J.E. Menard ,&nbsp;J.J. Morales ,&nbsp;V.A. Soukhanovskii","doi":"10.1016/j.nme.2025.101949","DOIUrl":"10.1016/j.nme.2025.101949","url":null,"abstract":"<div><div>Advances in vacuum, surface, and lithium conditioning techniques throughout five years of continuous operations in LTX-β have produced mirror-like liquid lithium surfaces and demonstrated the feasibility of high-performance tokamak discharges fully surrounded by liquid metal without significant operational problems. Improvements in conditioning techniques and procedures, including many weeks of baking and accumulation of 70 g of Li, led to reduced residual gasses and clean Li surfaces − all while still maintaining enough operational flexibility for multiple in-vacuum diagnostic upgrades and calibrations. Coatings had a visibly clean appearance, with reflective liquid metal demonstrating good wetting and surface adhesion with films that were now macroscopically thick. Solidified Li showed large crystal grains, while surface science measurements observed reduced impurities in the lithium. Steadily improved plasma performance was achieved with liquid lithium, with discharges able to match solid Li in terms of evolution of I_p and n_e, including rapid density pumping indicating low recycling. There were indications of moderately increased Li impurity influx, though few significant disturbances by the large liquid surfaces on tokamak operations over hundreds of discharges. Liquid metal plasma facing components are a potential solution to the extreme heat and particle fluxes that could cause unacceptable damage to solid materials, while liquid lithium also has the potential for greatly increased confinement in the low-recycling regime. While many liquid metal approaches are possible, and numerous experiments have been conducted in test stands and small modules in fusion devices, LTX-β is the only tokamak operated while fully surrounded by liquid metal.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101949"},"PeriodicalIF":2.3,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exhaust assessment of a European Volumetric Neutron Source (EU-VNS) using SOLPS-ITER","authors":"S. Wiesen ,&nbsp;Ch. Bachmann ,&nbsp;M. Siccinio ,&nbsp;J. Boscary ,&nbsp;C. Bourdelle ,&nbsp;M. Coleman ,&nbsp;G. Federici ,&nbsp;F. Maviglia ,&nbsp;R. Neu","doi":"10.1016/j.nme.2025.101939","DOIUrl":"10.1016/j.nme.2025.101939","url":null,"abstract":"<div><div>EUROfusion considers a volumetric neutron source (EU-VNS) to generate a neutron wall load of about <span><math><mrow><mn>0</mn><mo>.</mo><mn>5</mn><mspace></mspace><mi>M</mi><mi>W</mi><mo>/</mo><msup><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span> to qualify tritium breeding blankets early in support of EU-DEMO that mitigates the risk of a late testing for required nuclear technology. The envisaged small-scale <span><math><mrow><mi>R</mi><mo>=</mo><mn>2</mn><mo>.</mo><mn>5</mn><mspace></mspace><mi>m</mi></mrow></math></span> D-beam/T-target driven fusion device (<span><math><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>f</mi><mi>u</mi><mi>s</mi></mrow></msub><mo>≈</mo><mn>30</mn><mspace></mspace><mi>M</mi><mi>W</mi></mrow></math></span>) must exhaust helium particles and dissipate sufficient energy from the large auxiliary power required (<span><math><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>a</mi><mi>u</mi><mi>x</mi></mrow></msub><mo>≈</mo><mn>50</mn><mspace></mspace><mi>M</mi><mi>W</mi></mrow></math></span>) entering in large parts the edge. A SOLPS-ITER assessment indicates that with argon seeding a finite divertor operational window exists allowing to avoid core dilution by helium and to reduce the peak heat-flux density below <span><math><mrow><mn>10</mn><mspace></mspace><mi>M</mi><mi>W</mi><mo>/</mo><msup><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>. It is shown that an extra constraint of <span><math><mrow><msub><mrow><mi>Z</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub><mo>&lt;</mo><mn>2</mn><mo>−</mo><mn>3</mn></mrow></math></span>, required to sustain good core performance to produce the required amount of fusion neutrons, can also be met if the Greenwald-fraction <span><math><mrow><msub><mrow><mi>f</mi></mrow><mrow><mi>G</mi><mi>W</mi></mrow></msub><mo>≈</mo><mn>0</mn><mo>.</mo><mn>5</mn></mrow></math></span> is maintained with total T-throughputs at about half the ITER value. It is reasoned that for a EU-VNS design study the exhaust operational window can be enlarged by choosing other seeding species like Krypton, refining the balance between pellet- to gas-fuelling, and integrated core-edge modelling.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101939"},"PeriodicalIF":2.3,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143934629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First-principles study of beryllium thermodynamics and clustering mechanism in molybdenum: Effects of vacancies and self-interstitial atoms","authors":"Aoyu Mo ,&nbsp;Haijun Li ,&nbsp;Fuquan Guo ,&nbsp;Xiaowei Ma ,&nbsp;Yunshan Xiong ,&nbsp;Peng Shao ,&nbsp;Bo Li ,&nbsp;Kun Jie Yang ,&nbsp;Yue-Lin Liu ,&nbsp;Quan-Fu Han","doi":"10.1016/j.nme.2025.101948","DOIUrl":"10.1016/j.nme.2025.101948","url":null,"abstract":"<div><div>The clustering behavior of beryllium (Be) following plasma irradiation is of particular significance for molybdenum (Mo) in future fusion devices. Using first-principles calculations combined with thermodynamic models, the optimal configuration for Be clustering in Mo has been clearly determined, with a particular focus on the effects of vacancies and self-interstitials (SIAs). As the initial form of nucleation, the physical origin of Be-Be pair binding energy in Mo has been shown to be primarily dominated by the charge density at their location. Based on all of our computational results, a potential clustering mechanism for the formation of Be-rich regions in Mo is proposed: Be atoms first aggregate at interstitial sites, forming Be_n clusters. When the number of Be atoms reaches six, they form an approximately “octahedral” structure, displacing a central Mo atom and generating a Be₆V cluster and an SIA. They act as nucleation sites that continue to attract more Be atoms, growing into larger Be_nV and Be_n-SIA clusters. As the Be_n-SIA clusters expand, excess Be atoms displace more Mo atoms, creating additional SIAs and vacancies and further propagating the formation of Be_n-SIA and Be_nV clusters. This cascading process ultimately results in the development of Be-rich regions within Mo. Our results provide significant data support for advancing Mo as a primary mirror material and also offer valuable theoretical insights into the aggregation behavior of impurities in metals under irradiation conditions.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101948"},"PeriodicalIF":2.3,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144083796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A first study of the complex-concentrated-alloy W38Ta36Cr15V11 in Pisces-RF high-flux deuterium plasma","authors":"M.T. Vigil ,&nbsp;S. Faulhaber ,&nbsp;M.I. Patino ,&nbsp;A. Založnik ,&nbsp;D. Nishijima ,&nbsp;M.J. Simmonds ,&nbsp;B. Schwendeman ,&nbsp;K. Vecchio ,&nbsp;G.R. Tynan ,&nbsp;M.J. Baldwin","doi":"10.1016/j.nme.2025.101943","DOIUrl":"10.1016/j.nme.2025.101943","url":null,"abstract":"<div><div>Bulk targets of W₃₈Ta₃₆Cr₁₅V₁₁ complex concentrated alloy (CCA) were produced by spark plasma sintering at the Vecchio materials research lab at the University of California–San Diego. Targets fabricated were reasonably dense, BCC phase, compositionally close in match to that of El-Atwani et al. (2019), and homogeneous, as measured by electron microscopy, energy dispersive x-ray microanalysis (EDX), EDX mapping, and x-ray diffraction. The targets were exposed to deuterium plasma of associated 100 eV ion fluences of <span><math><mrow><mn>2</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>26</mn></mrow></msup></mrow></math></span> m⁻² at 523 K, 773 K and 1023 K in the <span>Pisces-RF</span> high-flux linear plasma device. Plasma exposure is found to produce surface compositional enrichment in W and Ta, as determined by Auger electron spectroscopy and EDX, that is caused by a depletion of surface Cr and V, the former being observed with optical emission spectroscopy in the target plasma. Accompanying the compositional change, transient grating spectroscopy analysis, taken pre- and post-plasma exposure on the 1023 K exposed target, revealed <span><math><mrow><mo>∼</mo><mn>30</mn><mtext>%</mtext></mrow></math></span> reduction in surface thermal diffusivity from <span><math><mrow><mn>9</mn><mo>.</mo><mn>4</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> m²s⁻¹ to <span><math><mrow><mn>6</mn><mo>.</mo><mn>7</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> m²s⁻¹. Lastly, D retention in the CCA targets was found to be characterized by a singular thermal release peak at <span><math><mrow><mo>∼</mo><mn>900</mn></mrow></math></span> K, and retention varied from <span><math><mrow><mn>2</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>23</mn></mrow></msup></mrow></math></span> m⁻² to <span><math><mrow><mn>3</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>20</mn></mrow></msup></mrow></math></span> m⁻² for exposure in the temperature range 523–1023 K, as measured by thermal desorption spectrometry. This level of D retention is found to be high relative to pure tungsten.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101943"},"PeriodicalIF":2.3,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143917316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning-based hydrogen recycling model for predicting rovibrational distributions of released molecular hydrogen on tungsten materials via molecular dynamics simulations","authors":"Seiki Saito ,&nbsp;Masato Iida ,&nbsp;Hiroaki Nakamura ,&nbsp;Keiji Sawada ,&nbsp;Kazuo Hoshino ,&nbsp;Masahiro Kobayashi ,&nbsp;Masahiro Hasuo ,&nbsp;Yuki Homma ,&nbsp;Shohei Yamoto","doi":"10.1016/j.nme.2025.101942","DOIUrl":"10.1016/j.nme.2025.101942","url":null,"abstract":"<div><div>Understanding the hydrogen recycling process is crucial for comprehending the behavior of detached plasma in nuclear fusion devices. To achieve this, a molecular dynamics (MD) model is being developed to predict the distribution of translational energies and rovibrational states of hydrogen atoms and molecules released from the plasma-facing materials. Neutral transport simulations, utilizing distributions obtained from the MD model as boundary conditions, are also a powerful tool for analyzing the impact of recycled hydrogens on edge plasma. However, the MD model requires significant computational resources to obtain distributions under varying material and irradiation conditions such as material temperature and incident energy. Therefore, developing effective models that seamlessly integrate neutral transport simulation with hydrogen recycling models is crucial. Machine learning techniques are employed to develop predictive models capable of forecasting distributions of energies and rovibrational states of released hydrogen atoms and molecules. Furthermore, a model considering the incident energy distribution (shifted-Maxwellian) is developed by integrating the monochromatic distribution with the shifted-Maxwellian distribution.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101942"},"PeriodicalIF":2.3,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of radiation profiles in a strongly baffled divertor on MAST Upgrade","authors":"Fabio Federici ,&nbsp;Matthew L. Reinke ,&nbsp;Bruce Lipschultz ,&nbsp;Jack J. Lovell ,&nbsp;Kevin Verhaegh ,&nbsp;Nicola Lonigro ,&nbsp;Cyd Cowley ,&nbsp;Mike Kryjak ,&nbsp;Peter Ryan ,&nbsp;Andrew J. Thornton ,&nbsp;James R. Harrison ,&nbsp;Byron J. Peterson ,&nbsp;Bartosz Lomanowski ,&nbsp;Jeremy D. Lore ,&nbsp;Yacopo Damizia ,&nbsp;EUROfusion Tokamak Exploitation Team ,&nbsp;MAST Upgrade team","doi":"10.1016/j.nme.2025.101940","DOIUrl":"10.1016/j.nme.2025.101940","url":null,"abstract":"<div><div>Plasma detachment in tokamaks is necessary in future tokamaks to sufficiently reduce the heat flux to the target. It involves interactions of the plasma with impurities and neutral particles, leading to significant losses of plasma power, momentum, and particles. An accurate mapping of plasma emissivity in the divertor and X-point region is essential to localise and infer the power losses influencing the detachment process. The recently validated InfraRed Video Bolometer (IRVB) diagnostic, in MAST-U (Federici et al., 2023), enables this mapping with higher spatial resolution than more established methods like resistive bolometers.</div><div>In previous preliminary work (Federici et al., 2023a), the detachment of the radiation from the target (radiative detachment) was characterised in L-mode (power entering the scrape-off layer, <span><math><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>S</mi><mi>O</mi><mi>L</mi></mrow></msub><mo>∼</mo></mrow></math></span>0.4 MW). With a conventional divertor the inner leg consistently detached ahead of the outer leg, and radiative detachment preceded particle flux detachment. This work presents results also from the third MAST-U experimental campaign, fuelled from the low field side instead of the high field side, including Ohmic and beam heated L-mode shots (with a power exiting the core up to <span><math><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>S</mi><mi>O</mi><mi>L</mi></mrow></msub><mo>∼</mo></mrow></math></span>1–1.5 MW).</div><div>The radiation peak moves upstream from the target at lower upstream densities than the ion target flux roll-over (typically considered the detachment onset), while radiation on the inner leg detaches before the outer one in high field side fuelled shots and about at the same time in low field side fuelled ones. The movement of the radiation is in partial agreement with the expectations from the DLS model (Myatra, 2021; Cowley et al., 2022; Lipschultz et al., 2016), predicting a sudden shift from the target to the X-point on the inner leg. The energy confinement is found to be related to detachment, but there seems to be some margin between the radiation peak caused by impurity radiation reaching the X-point and confinement being affected, a beneficial characteristic if it could be extrapolated to future reactors. For increasing <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>S</mi><mi>O</mi><mi>L</mi></mrow></msub></math></span> the particle flux roll-over happens for similar upstream densities. Comparing the total radiated power with the <span><math><msub><mrow><mi>D</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> Fulcher band emission evolution shows that in a conventional divertor a significant fraction of the radiated power is due to carbon radiation (outside of the divertor chamber).</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101940"},"PeriodicalIF":2.3,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143908227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-vessel colorimetry of Wendelstein 7-X first wall components after OP2.1","authors":"G. Motojima ,&nbsp;S. Masuzaki ,&nbsp;C.P. Dhard ,&nbsp;D. Naujoks ,&nbsp;Mattis Hänel ,&nbsp;Yu Gao ,&nbsp;the W7-X Team","doi":"10.1016/j.nme.2025.101934","DOIUrl":"10.1016/j.nme.2025.101934","url":null,"abstract":"<div><div>Colorimetry has been continuously utilized for the estimation of deposition layer distribution on the first wall panels and divertor target elements in each Operation Phases (OP) of Wendelstein 7-X (W7-X). In OP2.1, significant achievements were made in plasma-wall interaction studies and divertor performance, completed by the installation of actively cooled divertors together with the change of material from fine grain graphite to Carbon Fiber-reinforced Composite. This upgrade enabled the achievement of long-duration plasma discharges, reaching up to 500 s with a total injected energy of 1.3 GJ. Compared to a factor of 2.5 increase in the net average deposition thickness between OP1.2a and 1.2b, no significant change was observed between OP1.2b and OP2.1. The balance of deposition and erosion of deposition layer on the first wall panels is presumably changed in OP2.1. The considerable reasons are discussed qualitatively from the point of possibilities such as lower surface temperature of the divertor target elements, lower impurity level of bulk plasmas, and difference of the location of sputtered carbon source. Moreover, the clear pattern of the colorimetry on the divertor target elements is seen in OP1.2a and OP2.1 not in OP1.2b. However, it is not currently conclusive whether changes in reflectivity and optical properties on the graphite divertor surface are due to erosion or deposition.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101934"},"PeriodicalIF":2.3,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}