Nuclear Materials and Energy最新文献

{"title":"Dust collection after the high fluence campaign of the WEST tokamak","authors":"C. Arnas ,&nbsp;A. Campos ,&nbsp;M. Diez ,&nbsp;E. Bernard ,&nbsp;C. Brun ,&nbsp;C. Martin ,&nbsp;F. Gensdarmes ,&nbsp;S. Peillon ,&nbsp;E. Tsitrone ,&nbsp;the WEST team","doi":"10.1016/j.nme.2024.101848","DOIUrl":"10.1016/j.nme.2024.101848","url":null,"abstract":"<div><div>For Phase 2 of WEST, the lower divertor was entirely equipped with actively cooled ITER grade plasma-facing units made of chains of tungsten beveled monoblocks. In this configuration, dust particles were collected in 2023, after the first plasma campaign mainly dedicated to repetitive long pulses in the conditions of attached plasmas to the divertor. Due to a high particle fluence and a significant tungsten erosion, large quantities of dust were produced. In addition to those produced during off-normal events and the flaking of deposits which are typical of tokamak wall erosion, dust particles due to the flaking of pure tungsten thin layers deposited on the shadowed areas of beveled monoblocks were found. As specific characteristic, these thin layers may not adhere to the divertor and consequently, may be peeled off and mobilized during plasma operation.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101848"},"PeriodicalIF":2.3,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the 2H(3He, p0)4He nuclear reaction for deuterium depth profiling","authors":"Varvara Foteinou ,&nbsp;Fotios Maragkos ,&nbsp;Hans-Werner Becker ,&nbsp;Michael Kokkoris ,&nbsp;Matej Mayer ,&nbsp;Georgios Provatas ,&nbsp;Detlef Rogalla ,&nbsp;Thomas Schwarz-Selinger","doi":"10.1016/j.nme.2024.101853","DOIUrl":"10.1016/j.nme.2024.101853","url":null,"abstract":"<div><div>The differential cross sections of the ²H(³He,<!--> <!-->p₀)⁴He reaction have been determined at six detection angles (120°, 130°, 140°, 150°, 160° and 170°) in the energy range between 300 and 4000 <!--> <!-->keV, with steps of 30 to 100<!--> <!-->keV. The measurements were performed at the 4<!--> <!-->MV Dynamitron Tandem Laboratory of the Central Unit for Ion Beams and Radionuclides of the Ruhr University Bochum in Germany. A thin layer of amorphous deuterated hydrocarbon (a-C:D) plasma-deposited on a chromium substrate was used in all measurements. Overall, the results of the present study are in very good agreement with differential cross-section data available in the literature for similar detection angles, with an average deviation of less than 6 %.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101853"},"PeriodicalIF":2.3,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wall conditions on HL-2A and HL-3 tokamaks","authors":"Chengzhi Cao,&nbsp;Xiangmei Huang,&nbsp;Yi Hu,&nbsp;Yanfeng Xie,&nbsp;Jun Zhou,&nbsp;Tao Qiao,&nbsp;Jinming Gao,&nbsp;Laizhong Cai,&nbsp;Zeng Cao,&nbsp;HL-2A and HL-3 team","doi":"10.1016/j.nme.2024.101852","DOIUrl":"10.1016/j.nme.2024.101852","url":null,"abstract":"<div><div>This paper presents the wall conditioning of HL-2A and HL-3 tokamaks. It details the enhancement of plasma performance achieved through siliconization processes on the HL-2A tokamak, encompassing both offline and in-situ methodologies. A study on the impact of offline siliconization on impurity concentration within HL-2A is presented, and real-time siliconization results demonstrate that it has no effect on plasma discharge. The findings indicate that in-situ siliconization is equally effective as the offline process with regard to plasma performance. With appropriate 13.56 MHz radio frequency (RF) power and pressure, a uniform glow discharge was achieved under 0.1 T in HL-2A. The effectiveness of impurity removal on HL-3 at different baking temperatures has been investigated. Measurements of glow discharge plasma density and temperature reveal that the parameters farthest from the electrode are 6 eV and ∼ 8 × 10¹² m⁻³. Based on the breakdown tests, it was determined that the minimum breakdown voltage is approximate 430 V, and the lowest breakdown pressure is around 2.1 × 10^-2 Pa when using 2.1 MHz RF power. Furthermore, experiments were conducted to investigate the efficiency of radio frequency assisted glow discharge cleaning for impurity removal. The study also evaluated the effectiveness of various methods for removing impurities. Additionally, siliconization on HL-3 was implemented successfully with determination of all key control parameters.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101852"},"PeriodicalIF":2.3,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SOLPS-ITER simulations of the ITER divertor with improved plasma-facing component geometry","authors":"A.A. Pshenov,&nbsp;X. Bonnin,&nbsp;R.A. Pitts","doi":"10.1016/j.nme.2024.101851","DOIUrl":"10.1016/j.nme.2024.101851","url":null,"abstract":"<div><div>The ITER divertor design has been guided by SOLPS4.3 plasma boundary code simulations focused on baseline burning conditions at Q_DT = 10 which compose the majority of the existing ITER divertor scenario database. An effort is now underway, the first results of which are described here, to extend this database with improved SOLPS-ITER simulations adopting a newly implemented Grad-Zhdanov closure, the latest magnetic equilibrium featuring optimized wall clearances compared to that used in the original database, and a much higher fidelity model of the divertor structure, permitting a more realistic accounting of bypass conductances for neutrals around the divertor cassette body.</div><div>This paper focuses on the first throughput scan conducted for burning plasma conditions with 100 MW of power coming to the scape-off layer (SOL) and feedback controlled neon (Ne) seeding. The simulations show that the neutral gas reservoir “stored” underneath the divertor cassette is about a factor 10 higher than the number of main plasma nuclei in the SOL region. As a result, a strong neutral recirculation loop develops between the private flux region and the far-SOL via pathways around the divertor cassette body under high recycling conditions and is very effective at increasing dissipation in the far-SOL compared to the conventional SOLPS-ITER simulations with sub-divertor fueling at the same neutral pressure (p_n) underneath the dome. This leads to a drastic reduction of plasma temperature in front of the target plates in the far-SOL, eliminating any concern of tungsten sputtering from the divertor under stationary conditions at p_n sufficient to achieve peak heat flux mitigation. Since the pumping duct resides beneath the cassette body and is less accessible for neutrals entering the sub-divertor space, increasing the fidelity of the divertor structure model leads to a decrease of the pressure at the pumping duct for a given p_n. This in turn decreases both the fueling throughput required to maintain p_n at a given level and the helium (He) pumping efficiency, with the result that the upstream separatrix He concentration increases by several factors.</div><div>However, the simulations with higher fidelity description of the divertor using Monte-Carlo neutrals are extremely time consuming and hence cannot be routinely used despite the pronounced effect on the solution. A solution to this would be the development of a reduced model guided by a reasonably large database of simulations with a higher fidelity description of the divertor that would link the far-SOL fluxes to the private flux region (PFR) conditions.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101851"},"PeriodicalIF":2.3,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-vessel inspection of arc traces on the W7-X plasma facing components after the operation phase OP2.1","authors":"D. Hwangbo ,&nbsp;C.P. Dhard ,&nbsp;S. Kajita ,&nbsp;D. Naujoks ,&nbsp;Y. Gao ,&nbsp;The W7-X Team","doi":"10.1016/j.nme.2024.101846","DOIUrl":"10.1016/j.nme.2024.101846","url":null,"abstract":"<div><div>Updated distribution of arc traces across the interior walls after the operation phase 2.1 of Wendelstein 7-X (W7-X) is reported. A total of 105 new arc places were found, with 95% of them located around the stainless steel panels, diagnostic ports, and the glow discharge cleaning electrodes. Remaining 5% of the traces were found on carbon surfaces such as the graphite baffle and carbon fiber-reinforced composites divertor tiles, for the first time in W7-X. The arcing on the divertor tiles showed a retrograde motion, suggesting that the arcing must have occurred during the main plasma operations. A simple estimate of the mass loss due to arcing on the divertor area shows that <span><math><mo>∼</mo></math></span>0.2-0.3 g of carbon was eroded during OP2.1. This amount turns out to be a significantly smaller amount compared to the estimated losses due to sputtering, <span><math><mo>∼</mo></math></span>7.6 g/1800 s during OP1.2b (Brezinsek et al., 2021).</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101846"},"PeriodicalIF":2.3,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a spatial heterodyne spectrometer for time-resolved measurement of Zeeman effect on Hα emission line spectra","authors":"M. Xu ,&nbsp;T. Shikama ,&nbsp;M. Murakumo ,&nbsp;S. Kado ,&nbsp;M. Hasuo","doi":"10.1016/j.nme.2024.101850","DOIUrl":"10.1016/j.nme.2024.101850","url":null,"abstract":"<div><div>A spatial heterodyne spectrometer (SHS) for measuring the Zeeman effect on Hα emission line spectra was developed using an optimization design method that maximizes the product of the resolving power and etendue. Modified data processing steps were also used to improve the signal-to-noise (S/N) ratio of the spectra. The S/N ratio of the developed SHS was evaluated by measuring Ne I emission line spectra and compared with that of a Czerny–Turner spectrometer (CT) at a comparable resolving power. The results indicated that the S/N ratios of SHS spectra were approximately four times higher than those of CT spectra over an exposure time range of 0.5−80 ms. Additionally, Hα emission line spectra with the Zeeman effect were measured at magnetic field strength of 1−3 T comparable to that in a confinement device. It was confirmed that the theoretical instrumental function with a measured instrumental width can be used to analyze the line shape of multiple emission splitting lines.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101850"},"PeriodicalIF":2.3,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143173556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validation of SOLPS-ITER and EDGE2D-EIRENE simulations for H, D, and T JET ITER-like wall low-confinement mode plasmas","authors":"N. Horsten ,&nbsp;M. Groth ,&nbsp;V.-P. Rikala ,&nbsp;B. Lomanowski ,&nbsp;A.G. Meigs ,&nbsp;S. Aleiferis ,&nbsp;X. Bonnin ,&nbsp;G. Corrigan ,&nbsp;W. Dekeyser ,&nbsp;R. Futtersack ,&nbsp;D. Harting ,&nbsp;D. Reiter ,&nbsp;V. Solokha ,&nbsp;B. Thomas ,&nbsp;S. Van den Kerkhof ,&nbsp;N. Vervloesem ,&nbsp;JET Contributors","doi":"10.1016/j.nme.2024.101842","DOIUrl":"10.1016/j.nme.2024.101842","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Both experiments and simulations with SOLPS-ITER and EDGE2D-EIRENE show that the onset of detachment for the low-field side (LFS) divertor – defined here as the line-averaged upstream density (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;〉&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;edge&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) at which the plasma flux to the LFS target (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;LFS−plate&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) starts to decrease with increasing &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;〉&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;edge&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; – is independent of the isotope mass. However, there are three major simulation-experiment discrepancies: (i) the absolute values of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;LFS−plate&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and the electron density (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) in the LFS divertor at the onset of detachment are significantly lower in simulations, i.e., approximately a factor of 2 for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;LFS−plate&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and a factor of 3-4 for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;; (ii) the degree of detachment – defined here as the difference between &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;LFS−plate&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; at the onset of detachment and at an &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;〉&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;edge&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; value close to the density limit – is smaller in simulations compared to experiments; and (iii) the experimentally observed larger degree of detachment for D and T plasmas compared to H plasmas cannot be clearly distinguished from the simulation results. There are strong indications that discrepancy (i) is to a large extent caused by neglecting Lyman-opacity effects in our simulations. The simulations predict a similar net volumetric recombination source for all isotopes due to the fact that molecule-activated recombination (MAR) compensates for the reduced electron–ion recombination (EIR) for H, whereas MAR is negligible for D and T. This similar net volumetric recombination source for all isotopes leads to an isotope-independent degree of detachment in simulations. An analysis of the Balmer-&lt;span&gt;&lt;math&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and Balmer-&lt;span&gt;&lt;math&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; emission confirms the underestimate of MAR in simulations (especially for D and T) for the JET metallic wall, which was previously observed for devices with a carbon wall. The underestimate of MAR is an important cause for discrepancy (ii) and the fact that there is a stronger underestimate of MAR for D and T than for H explains discrepancy (iii)","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101842"},"PeriodicalIF":2.3,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Qualification by HHF tests of W coatings on Inconel superalloy for COMPASS-U plasma-facing components","authors":"Renaud Dejarnac ,&nbsp;Jiří Matějíček ,&nbsp;Henri Greuner ,&nbsp;Bernd Böswirth ,&nbsp;J. Gerardin ,&nbsp;Jaromír Kopeček ,&nbsp;Daniil Kirhetov","doi":"10.1016/j.nme.2024.101841","DOIUrl":"10.1016/j.nme.2024.101841","url":null,"abstract":"<div><div>Coating Inconel tiles by tungsten is a necessary step towards the full tungsten first wall coverage of the COMPASS-U tokamak. Thin tungsten coatings on Inconel based on physical vapor deposition were successfully produced consequently to a programme of R&amp;D within the COMPASS Upgrade project by three different suppliers. This contribution presents the qualification phase of these tungsten coatings under COMPASS-U relevant high heat fluxes (50 cycles at 10 <!--> <!-->MW/m², 100 cycles at 30 <!--> <!-->MW/m²) in the neutral beam test facility GLADIS. The behavior of the different tungsten coatings during exposures and the main conclusions from the post-mortem analysis are presented. The most important result is that under COMPASS-U relevant heat fluxes, no damage was observed on the front face of all samples, proving the practicability of such coatings for fusion application.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101841"},"PeriodicalIF":2.3,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143173563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-dose damage evolution in pure magnesium under electron irradiation: Effect of foil orientation and pre-existing dislocations","authors":"Hucheng Yu ,&nbsp;Xiaoou Yi ,&nbsp;Qi Chen ,&nbsp;Hao Fang ,&nbsp;Sichen Dong ,&nbsp;Shulei Li ,&nbsp;Wentuo Han ,&nbsp;Pingping Liu ,&nbsp;Somei Ohnuki ,&nbsp;Farong Wan","doi":"10.1016/j.nme.2024.101845","DOIUrl":"10.1016/j.nme.2024.101845","url":null,"abstract":"<div><div>Low-dose damage evolution in commercial purity (99.95 wt%) magnesium has been investigated, under 200 keV electron irradiation at room temperature, up to ∼0.03 displacements per atom. Quantitative defect production and evolution statistics were obtained for two types of prism foils (<strong>z</strong> = [<span><math><mrow><mtext>1</mtext><mover><mrow><mtext>2</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>10</mtext></mrow></math></span>], [<span><math><mrow><mtext>10</mtext><mover><mrow><mtext>1</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>0</mtext></mrow></math></span>]), in samples of as-received and heat-treated (400 °C/1 h) condition. An incubation period was found to produce visible damage in all samples, in correspondence with about ⅓ of the maximum dose. The damage microstructure consisted of basal-plane <span><math><mfrac><mn>1</mn><mn>6</mn></mfrac></math></span>&lt;<span><math><mrow><mn>20</mn><mover><mrow><mn>2</mn></mrow><mrow><mo>¯</mo></mrow></mover><mn>3</mn></mrow></math></span>&gt; loops, exclusively; while no voids were observed throughout the course of irradiations. Steady-state accumulation of dislocation loops was found at doses beyond the incubation limit in heat-treated samples. Higher loop number density and large loop average size were confirmed in [<span><math><mrow><mtext>1</mtext><mover><mrow><mtext>2</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>10</mtext></mrow></math></span>] than in [<span><math><mrow><mtext>10</mtext><mover><mrow><mtext>1</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>0</mtext></mrow></math></span>]. One-dimensional loop rafts were developed via elastic interaction. In as-received samples, the presence of pre-existing dislocations (on the order of 10¹⁴ m⁻²) gave rise to suppressed build-up of loop population. Saturation of loop growth was confirmed, when loop average size reached ∼20 nm. Underlying mechanisms of foil orientation effect and pre-existing dislocation effect upon microstructure development are discussed. The paper concludes with a brief comparison between electron irradiation and fission neutron irradiation in magnesium, aiming to bring new insights upon displacement damage studies in materials with hexagonal close-packed structure.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101845"},"PeriodicalIF":2.3,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glow Discharge Boronization and Real-Time Boronization Using an Impurity Powder Dropper in LHD","authors":"S. Masuzaki ,&nbsp;M. Shoji ,&nbsp;F. Nespoli ,&nbsp;R. Lunsford ,&nbsp;G. Motojima ,&nbsp;M. Yajima ,&nbsp;M. Tokitani ,&nbsp;T. Oishi ,&nbsp;T. Kawate ,&nbsp;M. Goto ,&nbsp;H. Kasahara ,&nbsp;Y. Yoshimura ,&nbsp;E.P. Gilson ,&nbsp;N. Pablant ,&nbsp;T. Morisaki","doi":"10.1016/j.nme.2024.101843","DOIUrl":"10.1016/j.nme.2024.101843","url":null,"abstract":"<div><div>In the Large Helical Device (LHD), boronization is utilized for wall conditioning, employing two distinct methods: glow discharge using diborane gas and the injection of boron powder into the plasma via an impurity powder dropper (IPD). Glow discharge boronization is conducted after maintenance when the vacuum vessel is exposed to air and just before the start of an experimental campaign. In contrast, real-time boronization using the IPD is performed during discharges. The distribution of boron on plasma-facing components was assessed through long-term material probes in the case of glow discharge and through numerical simulations for the IPD method. Results indicated non-uniform boron distributions in both cases. The impact of these boronization techniques on impurity levels and the lifetime of their effects were also examined. Both methods effectively reduced oxygen and iron in the plasma, with the iron impurities originating from the first wall. For glow discharge boronization, the reduction in oxygen levels persisted until the end of the experimental campaign, whereas the reduction in iron levels only lasted a few days. In the case of boron injection during long pulse discharges exceeding 200 s, the suppression of oxygen and iron was observed. The effect on iron quickly diminished within several seconds after the injection ended, whereas the effect on oxygen lasted more than 100 s. The difference in the lifetimes of the boronization effects is further discussed.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"42 ","pages":"Article 101843"},"PeriodicalIF":2.3,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143173557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}