Nuclear Materials and Energy最新文献

{"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}

{"title":"Compositionally-driven surface nanostructuring on refractory compositionally complex alloys under low energy helium bombardment","authors":"Shane Evans ,&nbsp;Justin Hamil ,&nbsp;Matthew J. Baldwin ,&nbsp;Daisuke Nishijima ,&nbsp;Marlene I. Patino ,&nbsp;Megan J. McCarthy ,&nbsp;Andrew B. Kustas ,&nbsp;Mary Alice Cusentino ,&nbsp;Eric Lang","doi":"10.1016/j.nme.2025.101946","DOIUrl":"10.1016/j.nme.2025.101946","url":null,"abstract":"<div><div>Additive manufacturing enables user-defined control of the compositional complexity, opening new design spaces for complex concentrated alloys (CCAs). Refractory CCAs may offer enhanced performance in the divertor region of a fusion reactor environment where plasma-facing materials will be subject to high temperatures, low energy He and D particles, and 14 MeV neutrons. In this work, specimens with the nominal composition of NbTaMoTi, NbTaMo, NbTaTi, and NbTa were fabricated via directed energy deposition (DED) then bombarded with 40 eV He ions to a fluence of 2x10²⁶ m⁻² at ∼ 1000 K. Post irradiation, the surface morphology and composition were examined with electron microscopy and x-ray photoelectron spectroscopy to offer information on the spatial distribution of surface nano-structuring. Sub-surface He bubbles driving the nano-structuring were examined with electron microscopy techniques. Analysis indicates the local composition directly influences the He bubble and tendril size, while the region with the highest complexity showed the shortest nano-structuring. Molecular Dynamics simulations complement the experimental results, showing comparable helium bubble growth and migration as a function of compositional complexity. This work demonstrates the compositional dependence of surface nanostructure formation of compositionally complex alloys, important for future design of complex plasma facing materials in fusion reactors.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101946"},"PeriodicalIF":2.3,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143924016","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":"High-speed camera observation of Hα, Hβ and Hγ associated with mutual neutralization and EIR in GAMMA 10/PDX divertor simulated plasma","authors":"S. Takahashi,&nbsp;N. Ezumi,&nbsp;T. Okamoto,&nbsp;K. Kono,&nbsp;H. Kawahara,&nbsp;T. Seto,&nbsp;R. Miyauchi,&nbsp;S. Togo,&nbsp;M. Hirata,&nbsp;J. Kohagura,&nbsp;M. Yoshikawa,&nbsp;Y. Nakashima,&nbsp;M. Sakamoto","doi":"10.1016/j.nme.2025.101945","DOIUrl":"10.1016/j.nme.2025.101945","url":null,"abstract":"<div><div>For the purpose of gaining a better understanding of detached plasma formation, the transition of the volumetric plasma recombination processes of the end-loss hydrogen plasma of a tandem-mirror, GAMMA 10/PDX, was investigated. In the Divertor Experimental Module (D-module) on the end cell, where the additional hydrogen gas is injected, the plasma flows into the V-shaped tungsten target plates. A 4-branch high-speed camera system was used to observe the 2D distributions of H_α, H_β and H_γ emission intensities simultaneously. As the neutral gas pressure (<em>p</em>_n) in the D-module increased, two distinct emission phases were observed. The first phase was characterized by an initial increase followed by a decrease in H_α emission, coinciding with a rollover of the electron density (<em>n</em>_e). This behavior is associated with the mutual neutralization of H⁺ and H^-, a process associated with molecular activated recombination (MAR). Further increase in <em>p</em>_n led to the second phase, during which a drastic increase in H_β and H_γ emissions alongside H_α was seen and the interferometer indicated a re-increase in <em>n</em>_e up to at least ∼ 4 × 10¹⁸ m⁻³, while the spectrometer observed an increase in Balmer emission intensities from higher excited states (n ≥ 5). The electron temperature (<em>T</em>_e) was estimated to be less than ∼ 0.1 eV using the Boltzmann plot method. These results suggest a shift in the dominant volumetric recombination mechanisms, with mutual neutralization of H₂⁺ and H^- becoming significant alongside electron–ion recombination (EIR), a process previously thought to be negligible in GAMMA 10/PDX.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101945"},"PeriodicalIF":2.3,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143941763","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":"Influence of thermal treatment at various temperatures on structure and radiation-induced effects in advanced ceramic breeder pebbles","authors":"A. Ansone ,&nbsp;A. Antuzevics ,&nbsp;L. Avotina ,&nbsp;E. Sprugis ,&nbsp;A. Trimdale-Deksne ,&nbsp;J.M. Leys ,&nbsp;R. Knitter ,&nbsp;A. Zarins","doi":"10.1016/j.nme.2025.101944","DOIUrl":"10.1016/j.nme.2025.101944","url":null,"abstract":"<div><div>Advanced ceramic breeder (ACB) pebbles consisting of 65 mol% lithium orthosilicate (Li₄SiO₄) and 35 mol% lithium metatitanate (Li₂TiO₃) are currently being developed as the European Union’s reference material for tritium breeding in future thermonuclear fusion reactors. In the present work, the influence of thermal treatment at various temperatures on structure and radiation-induced effects in the ACB pebbles is investigated. The produced ACB pebbles were thermally treated at selected temperatures between 500 and 1000 °C in different atmospheres (air, argon, and vacuum) and afterwards irradiated using X-rays with energies up to 45 keV. The formed and accumulated paramagnetic radiation-induced defect centres in the irradiated ACB pebbles before and after thermal treatment were analysed using electron paramagnetic resonance (EPR) spectroscopy. To determine the exact temperatures of the phase transitions and evaluate the influence of thermal treatment on the crystal structure, chemical bond vibrations, and microstructure of the ACB pebbles before irradiation, several other relevant physico-chemical analytical methods were applied: differential scanning calorimetry/thermogravimetry (DSC/TG), powder X-ray diffraction (PXRD) technique, attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). On the basis of the obtained results, it can be concluded that thermal treatment at temperatures higher than 700 °C influences the distribution of paramagnetic centres generated by exposure to X-rays. This is probably due to the second-order phase transition from “low-temperature” to “high-temperature” structure of the Li₄SiO₄ phase between 600 and 750 °C. The obtained results highlight the importance of considering the thermal treatment temperature of the produced ACB pebbles prior to irradiation when analysing these ceramic materials using EPR spectroscopy techniques.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101944"},"PeriodicalIF":2.3,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891024","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":"Study of line spectra emitted by hydrogen isotopes in tokamaks through Deep-Learning algorithms","authors":"N. Saura,&nbsp;M. Koubiti,&nbsp;S. Benkadda","doi":"10.1016/j.nme.2025.101935","DOIUrl":"10.1016/j.nme.2025.101935","url":null,"abstract":"<div><div>Artificial Intelligence (AI) is increasingly used in various plasma physics topics, including applications in spectroscopy and diagnostics in magnetically confined fusion plasmas. The paper focuses on the application of the convolutional neural network (CNN) algorithm to emission spectroscopy from the divertor regions of magnetic fusion devices. Specifically, we use a CNN to determine hydrogen isotopic ratios from the theoretical emission spectra of the Balmer-α line in hydrogen–deuterium (HD) plasmas. The motivation for coupling AI with spectroscopy is to develop novel frameworks that can outperform existing classical methods based on spectral line fitting, in terms of accuracy, speed, or adaptability. In a previous work, we have used a fully connected neural network algorithm for theoretical Hα/Dα line spectra emitted by HD plasmas which have been generated for conditions relevant to divertor plasmas in tokamaks (magnetic field, neutral temperatures and fractions and hydrogen concentration). The generated spectra were preprocessed to extract few spectroscopic features which were then used as input data by the neural network. In the present work, we apply for the first time a CNN model to raw synthetic Hα/Dα line spectra theoretically emitted by HD plasmas to predict the corresponding isotopic ratios. In this context, we show that the trained CNN predicts hydrogen isotopic ratios with deviations of up to 5% from the true values. Additionally, our model can generalize its predictions to spectra corresponding to any observation angle relative to the magnetic field, despite being trained solely on spectra from parallel observations. The prediction accuracy in these cases is comparable to the training accuracy.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101935"},"PeriodicalIF":2.3,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143882139","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":"Balmer emission measurements in JET-ILW hydrogen, deuterium, tritium and deuterium-tritium low-confinement mode plasmas","authors":"A.G. Meigs ,&nbsp;M. Groth ,&nbsp;V.-P. Rikala ,&nbsp;B. Lomanowski ,&nbsp;N. Vianello ,&nbsp;M. Wischmeier ,&nbsp;the JET contributors","doi":"10.1016/j.nme.2025.101941","DOIUrl":"10.1016/j.nme.2025.101941","url":null,"abstract":"<div><div>Measurements of Balmer-alpha (B-α) and Balmer-gamma (B-γ), where B = H, D, or T isotopes of hydrogen, emission across the low-field side (LFS) divertor in JET ITER-like Wall (ILW), low-confinement mode (L-mode) plasma indicate that the divertor plasma was more strongly detached in deuterium, tritium and deuterium–tritium than in hydrogen plasmas. These measurements are consistent with the lower degree of detachment in hydrogen versus tritium plasmas inferred from Langmuir probes (Groth et al., 2023) [<span><span>1</span></span>]. The ratio of B-γ to B-α is a suitable indicator of high density/low temperature conditions because B-α emission is dominated by electron impact excitation with a small electron–ion recombination component regardless of electron temperature and density (for conditions in tokamak plasmas) whilst for B-γ the recombination component increases and the excitation component decreases as the electron temperature decreases and the electron density increases. Within the uncertainty of the measurements, the electron density at the low-field side separatrix and the power crossing the separatrix are similar to permit these comparisons. The B-©/B-α ratio is well correlated with the onset of detachment as measured by Langmuir probes (McCracken et al., 1998; Groth et al., 2023). The ratios of B-γ and B-α varied between 0.005 and 0.035 for low-recycling, high-recycling and partially detached conditions, and were 60–70 % higher in partially detached hydrogen than in tritium plasmas. In contrast, the difference between deuterium, tritium and 40–60 % deuterium–tritium is within 10 % and thus within the uncertainties of the measurements. Profiles of the B-α and B-γ emission was measured with two filtered CCDs connected to the visible lost light leg of JET’s mirror link spectroscopy system (Meigs et al., 2010; Lomanowski et al., 2014)[<span><span>4</span></span>,<span><span>5</span></span>]. Spatially (radial) narrower B-α profiles were measured with increasing isotope mass, while similarly broadened B-γ profiles were measured.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101941"},"PeriodicalIF":2.3,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865093","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":"Microstructural characterization and low-cycle fatigue behavior of ODS steel prepared by precursor-assisted cast technology","authors":"Yanyun Zhao ,&nbsp;Boyang Zhang ,&nbsp;Yu Si ,&nbsp;Shiao Ding ,&nbsp;Qijing Sun ,&nbsp;Kunjie Yang ,&nbsp;Qiang Zhen ,&nbsp;Xiaodong Mao","doi":"10.1016/j.nme.2025.101933","DOIUrl":"10.1016/j.nme.2025.101933","url":null,"abstract":"<div><div>The microstructural evolution and cyclic deformation behavior of oxide dispersion-strengthened (ODS) steel fabricated by precursor-assisted cast technology (PACT) were systematically investigated through multi-scale characterization methods. Low-cycle fatigue tests were performed at 650 °C with total strain amplitudes ranging from ± 0.4 % to ± 1.0 % to investigate the deformation mechanisms and the stability of nano-oxides. The evolution of dislocation structures and nano-oxide distributions was characterized using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) at critical fatigue stages. Regions with a high oxide density exhibit enhanced resistance to cyclic softening, indicating a strong correlation between dislocation structure evolution and nano-oxide distribution. Fractographic examination using scanning electron microscopy (SEM) reveals transgranular crack propagation without failure initiation at inclusions, confirming the microstructural homogeneity achieved through PACT. This comprehensive characterization demonstrates that the PACT produces ODS steels with stable nano-oxide dispersions and improved resistance to cyclic deformation at elevated temperatures.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101933"},"PeriodicalIF":2.3,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868546","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 plasma-chemical mechanism of surface destruction of the diagnostic system components inside EAST vacuum vessel","authors":"L.G. Lobanova ,&nbsp;S. Wang ,&nbsp;H. Lian ,&nbsp;X. Cui ,&nbsp;J. Chen ,&nbsp;R. Yan ,&nbsp;L. Zhang ,&nbsp;V.P. Afanas’ev ,&nbsp;H. Liu","doi":"10.1016/j.nme.2025.101938","DOIUrl":"10.1016/j.nme.2025.101938","url":null,"abstract":"<div><div>The study investigates the causes of surface degradation of the retro reflectors, made of polycrystalline molybdenum, used in the optical diagnostic polarimeter/interferometer (POINT) system on the EAST tokamak. The component and depths profiling analysis of the retro reflectors surface was conducted based on the interpretation of X-ray photoelectron spectroscopy (XPS) energy spectra. The depths profiling analysis was performed using argon ion sputtering with an energy of 2 keV to a depth of 60 nm. On the uncleaned retro reflectors surface, the following was observed: the predominant presence of molybdenum trioxide (MoO₃), no presence of unoxidized molybdenum, and the presence of elements from constructional details, including C and B, Zn, Fe, Cu, Ca, Na with quantities not exceeding 1 %. It was established that the main cause of surface degradation of the retro reflectors and, consequently, the degradation of their reflective properties, is the active chemical oxidation of molybdenum during technical breaks and in the absence of plasma discharges, followed by the plasma-chemical removing of molybdenum oxides under plasma discharge conditions. The cyclic process of surface oxidation by water vapor and oxygen and subsequent removing of molybdenum oxides due to the heating and the interaction of the retro reflectors surface with plasma, leads to the formation of a well-developed morphology on the retro reflectors surface and, thus, to the reflectivity degradation. It is noted that similar processes occur with inner vacuum vessel materials, which consist of transition metals, such as W and Mo.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101938"},"PeriodicalIF":2.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851675","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}