Nuclear Materials and Energy最新文献

{"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":"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}

{"title":"Gas puff imaging of plasma turbulence in the magnetic island scrape-off layer of W7-X","authors":"S.G. Baek ,&nbsp;S. Ballinger ,&nbsp;O. Grulke ,&nbsp;C. Killer ,&nbsp;A. von Stechow ,&nbsp;J.L. Terry ,&nbsp;F. Scharmer ,&nbsp;B. Shanahan","doi":"10.1016/j.nme.2025.101937","DOIUrl":"10.1016/j.nme.2025.101937","url":null,"abstract":"<div><div>The turbulence characteristics of the scrape-off-layer (SOL) plasma in the W7-X stellarator are investigated using a gas-puff-imaging (GPI) diagnostic, newly installed and operated during the OP 2.1 campaign. The SOL plasma on W7-X features a set of island divertors for heat and particle exhaust and provides a unique environment for studying SOL turbulence and transport. This paper focuses on the O-point region of the magnetic island divertor SOL in the standard magnetic configuration. Fourier and cross-correlation analyses show that turbulence flows are predominantly in the poloidal direction (i.e., direction tangent to the last closed flux surface) with significantly weaker radial motion. This suggests dominant ExB convection and suppressed filamentary transport compared to those observed in the far scrape-off-layer region of tokamaks, as further supported by high-resolution skewness and kurtosis data that show the absence of intermittent, bursty filamentary events. Additionally, a relationship between the radial profile of the connection length and the sheared poloidal flow structure is reported, suggesting a possible linkage among magnetic topology, turbulence dynamics, and turbulence generation.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101937"},"PeriodicalIF":2.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143874771","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":"Impurity study to assess N = 1D ICRF heating scenario in T-rich plasmas with D-beams during JET-ILW DT experimental campaigns","authors":"A. Chomiczewska ,&nbsp;W. Gromelski ,&nbsp;I. Ivanova-Stanik ,&nbsp;E. Kowalska-Strzęciwilk ,&nbsp;N. Wendler ,&nbsp;M. Maslov ,&nbsp;E. Lerche ,&nbsp;G. Pucella ,&nbsp;JET contributors ,&nbsp;the EUROfusion Tokamak Exploitation Team","doi":"10.1016/j.nme.2025.101936","DOIUrl":"10.1016/j.nme.2025.101936","url":null,"abstract":"<div><div>A JET D-T scenario with optimised non-thermal fusion has been developed and successfully demonstrated during the second JET deuterium–tritium campaign (DTE2) at JET-ILW [<span><span>1</span></span>]. By using fundamental deuterium (D) minority ICRF heating scenario (N = 1 D) and pure D-NBI heating in T-rich plasmas, an energy world record for the most fusion energy produced in a single fusion shot has been achieved, by generating 69 MJ of heat from fusion reactions. During scenario optimisation, a systematic study of impurity behaviour has been performed. The impurities were analysed using various diagnostic techniques, e.g. VUV, VIS spectroscopy, and bolometry. The influence of different factors, including the plasma parameters and the heating methods has been investigated. The high-power T-rich hybrid pulses with different D gas puff rates in the main heating phase were compared to determine the influence of the D/T ratio on impurity behaviour. It was found that the intrinsic impurity content and the radiated power increase with the D/T ratio. Additionally, discharges in T-rich plasmas were compared with hybrid-like pulses with 50/50 D/T plasma mixtures and different ICRF heating schemes. It was found that T-rich plasmas, in which the highest fusion power was achieved are characterised by the lowest impurity content and highest ELM frequency (f_ELM ∼ 80–100 Hz), which increases with the fuelling rate. In some cases, the duration of the high-performance phase in T-rich plasmas was limited by impurity accumulation in the plasma core. Experimental and theoretical investigation showed that the high-Z impurity accumulation is related to the impurity transport inside the plasma and not related to the impurity source.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101936"},"PeriodicalIF":2.3,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847304","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":"Impact of nitrogen molecular breakup on divertor conditions in JET L-mode plasmas using SOLPS-ITER","authors":"R. Mäenpää ,&nbsp;H. Kumpulainen ,&nbsp;M. Groth ,&nbsp;N. Horsten ,&nbsp;D. Reiter ,&nbsp;J. Romazanov ,&nbsp;B. Lomanowski ,&nbsp;S. Brezinsek ,&nbsp;J. Karhunen ,&nbsp;K.D. Lawson ,&nbsp;A.G. Meigs ,&nbsp;S. Menmuir ,&nbsp;A. Shaw ,&nbsp;JET Contributors ,&nbsp;EUROfusion Tokamak Exploitation Team","doi":"10.1016/j.nme.2025.101929","DOIUrl":"10.1016/j.nme.2025.101929","url":null,"abstract":"<div><div>SOLPS-ITER simulations of nitrogen-seeded, low-confinement mode plasmas in the Joint European Torus (JET) predict that the electron temperature in the low-field side (LFS) divertor leg is reduced locally by up to an order of magnitude when nitrogen is assumed to recycle as molecules (N₂) instead of atoms using a fixed nitrogen injection rate. The LFS divertor temperature reduction under the assumption of molecular recycling occurs due to a three-step mechanism: (1) the plasma penetration of nitrogen atoms is increased due to the strong triple bond of the N₂ molecule and the kinetic energy release in the dissociation event, both mechanisms contributing equally, (2) the abundance of (particularly multiply-charged) nitrogen ions in the divertor is increased and (3) the electron temperature is reduced due to the increase in radiation (by up to a factor of 4) from nitrogen ions.</div><div>Setting the volume-integrated nitrogen radiated power to a constant value (0.6<!--> <!-->MW) instead of the nitrogen injection rate, SOLPS-ITER predicts under the molecular nitrogen recycling assumption that the peak line-integrated N II, N III and N IV intensities in the LFS divertor are approximately within 15%, 35% and 5%, respectively, of the reference atomic nitrogen recycling case. The predicted peak N II, N III and N IV intensities under either assumption are within 30%, 65% and 5%, respectively, of measurements using the vertically viewing mirror-link divertor spectrometer (Meigs et al., 2010) in nitrogen-seeded JET L-mode plasmas (Lomanowski et al., 2019). ERO2.0 simulations using a constant nitrogen seeding rate on static background plasma solutions from EDGE2D-EIRENE (previously presented in Mäenpää et al., (2022), revised here to include fast reflections) predict that N II to N IV line emission is increased by 20% to 30% when nitrogen is assumed to recycle as molecules, demonstrating the importance of considering the effect of molecular dissociation reactions on the divertor plasma in a self-consistent manner.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101929"},"PeriodicalIF":2.3,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833444","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":"Blob velocities and sizes in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas","authors":"A.D. Helgeland ,&nbsp;J.M. Losada ,&nbsp;J.L. Terry ,&nbsp;O.E. Garcia","doi":"10.1016/j.nme.2025.101930","DOIUrl":"10.1016/j.nme.2025.101930","url":null,"abstract":"<div><div>An improved time delay estimation method is used to calculate the velocity of cross-field blob motion in the scrape-off layer of Alcator C-Mod for an ohmic and two high confinement (H-mode) plasmas; an edge localized mode free and an enhanced D-alpha H-mode. The gas puff imaging data analysis results are interpreted in the framework of a stochastic model that describes the fluctuations as a super-position of uncorrelated blob-like structures. In all confinement modes investigated, the scrape-off layer is dominated by large amplitude, blob-like filaments moving radially outwards with velocities in the range from 400 to <span><math><mrow><mn>1000</mn><mspace></mspace><mspace></mspace><mi>m/s</mi></mrow></math></span>. Blobs in high confinement mode plasmas have similar velocities and sizes as in ohmic plasma, which is consistent with the close similarity of conditionally averaged burst shapes and frequency spectra for the confinement modes investigated.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"43 ","pages":"Article 101930"},"PeriodicalIF":2.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895607","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}