Journal of Fusion Energy最新文献

{"title":"Investigation of Development of Density Profiles in Start-Up Phase of DEMO and Fueling/Heating Scenario Using TASK/TR Code","authors":"Kento Miyamae,&nbsp;A. Fukuyama,&nbsp;H. Yamada,&nbsp;S. Kajita","doi":"10.1007/s10894-025-00533-z","DOIUrl":"10.1007/s10894-025-00533-z","url":null,"abstract":"<div><p>This study has investigated the effect of particle transport of fuel ions, deuterium (D) and tritium (T), and helium ash (He) as well as their heat transport on the nuclear fusion output in a DEMO reactor. The result was assessed and possible start-up scenarios for DEMO was discussed. In the study, the integrated tokamak modeling code, TASK/TR is used to investigate the impact of the neutral beam injection (NBI) fuel source on the plasma density distribution. It was found that, due to the dilution from burn-up and helium ash, the fuel density profile becomes either flat or hollow in the core region when fuel is supplied only from the periphery. The reduction of core fuel dilution by NBI is discussed in the context of the results, highlighting the potential of NBI to mitigate the hollow density profile and enhance the central fueling during startup.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10894-025-00533-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145675624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Edge Magnetic Island on Thermal Instability, Equilibrium, and Detachment Dynamics Induced by Impurity Radiation in LHD","authors":"Masahiro Kobayashi,&nbsp;Kiyofumi Mukai,&nbsp;Yuki Hayashi,&nbsp;Masato I.N. Kobayashi,&nbsp;Shigeru Morita,&nbsp;Mikhail Z. Tokar,&nbsp;Yuehe Feng,&nbsp;Tetsutarou Oishi,&nbsp;Ryohtaroh T. Ishikawa,&nbsp;Ken-ichi Nagaoka,&nbsp;Peterson Byron,&nbsp;Suguru Masuzaki,&nbsp;Yoshiro Narushima,&nbsp;Motoshi Goto","doi":"10.1007/s10894-025-00530-2","DOIUrl":"10.1007/s10894-025-00530-2","url":null,"abstract":"<div><p>The impact of edge magnetic islands on divertor detachment in LHD is investigated, with emphasis on thermal instability and thermal equilibrium. During a density ramp-up, as the edge plasma temperature is reduced, radiation is enhanced in cases with an edge magnetic island compared to those without one, and the detached plasma state remains stable. In contrast, in the absence of the island, the increase in radiation becomes uncontrollable, ultimately leading to a radiation collapse of plasma. Analysis of thermal instabilities indicates that the X- and O-points of the island are particularly susceptible to thermal instability due to their distinct magnetic topologies. Impurity radiation measurements reveal that, during density ramp-up, radiation initially emerges around the island’s X-point. Following the detachment transition, the location of peak radiation shifts to the O-point, where signatures of volume recombination are observed. Numerical simulations of edge plasma transport reproduce these dynamic trends, which reinforces the experimental interpretation. Thermal instability growth rates estimated from experimental data indicate that, within the island’s O-point, the growth rates decrease as detachment deepens; in contrast, in the absence of the island, the growth rates continue to increase, approaching radiation collapse. Additional aspects of thermal instability and radial thermal equilibrium are discussed to elucidate the factors contributing to detachment stabilization and to outline remaining challenges for future investigations.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10894-025-00530-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145675623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High Power Long Pulse Experiment by ICRF Heating in LHD","authors":"Tetsuo Seki,&nbsp;Hiroshi Kasahara,&nbsp;Ryosuke Seki,&nbsp;Kenji Saito,&nbsp;Shuji Kamio,&nbsp;Goro Nomura,&nbsp;Motonari Kanda","doi":"10.1007/s10894-025-00536-w","DOIUrl":"10.1007/s10894-025-00536-w","url":null,"abstract":"<div>\u0000 \u0000 <p>Long pulse discharge experiments have been conducted at LHD as one of the challenges in the quest for a fusion reactor. The plasma could be sustained for 48 min, using 1.2 MW of heating power from the ion cyclotron range of frequencies (ICRF) and electron cyclotron heating (ECH) power. The line-averaged electron density was 1.2 × 10¹⁹m^-3, the ion and electron temperature was 2 keV, and the input energy reached 3.36 GJ. The ICRF antennas used were the HAS (handshake form) and the FAIT (field-aligned-impedance-transforming) type, which upgraded and replaced the existing PA (poloidal array) antennas, in addition to the existing PA antenna. These antennas had the following characteristics. The PA one had a Faraday shield on one antenna strap removed. The HAS antenna’s straps were aligned in the toroidal direction and was phase controllable in the toroidal direction. The FAIT antenna had a built-in impedance transformer to obtain high plasma loading resistance. Long pulse discharges are often terminated by an influx of impurities, which are the result of exfoliation of deposits left during the discharges. Overcoming this impurity problem is one of the challenges of a steady state operation.</p>\u0000 </div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10894-025-00536-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145613087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive Assessment of Tritium to the Environment Discharged By Deuterium Plasma Experiment Using Large Helical Device, Japan","authors":"Naofumi Akata,&nbsp;Takuya Saze,&nbsp;Haruka Kuwata,&nbsp;Chie Iwata,&nbsp;Miki Nakada,&nbsp;Saori Kurita,&nbsp;Hiroshi Hayashi,&nbsp;Hitoshi Miyake,&nbsp;Masahiro Tanaka","doi":"10.1007/s10894-025-00532-0","DOIUrl":"10.1007/s10894-025-00532-0","url":null,"abstract":"<div><p>At the National Institute of Fusion Science (NIFS), the deuterium plasma experiment was conducted using the large helical device (LHD) from 2017 to 2022 for the high performance of the plasma experiment. Through this experiment, a small amount of tritium was produced by D-D fusion reaction and released to the atmospheric environment through the stack. To understand the impact of tritium on the environment, environmental tritium monitoring was conducted before, during, and after the experiment for public acceptance and in accordance with local governments. From this monitoring, no impacts were observed on monthly precipitation and pine needle samples at the NIFS site. As the result of a comprehensive assessment combined with atmosphere and environmental water monitoring, it was concluded that the impact of discharged tritium from the stack of LHD to the surrounding environment would be none and/or negligibly small.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10894-025-00532-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impurity Powder Injection Experiments in the Large Helical Device","authors":"F. Nespoli,&nbsp;S. Masuzaki,&nbsp;K. Tanaka,&nbsp;M. Shoji,&nbsp;R. Lunsford,&nbsp;N. Ashikawa,&nbsp;E. P. Gilson,&nbsp;N. Tamura,&nbsp;D. Medina-Roque,&nbsp;T. Kawate,&nbsp;T. Oishi,&nbsp;K. Ida,&nbsp;M. Yoshinuma,&nbsp;Y. Takemura,&nbsp;T. Kinoshita,&nbsp;G. Motojima,&nbsp;M. Osakabe,&nbsp;N. Kenmochi,&nbsp;G. Kawamura,&nbsp;T. Singh,&nbsp;H. Takahashi,&nbsp;K. Ogawa,&nbsp;C. Suzuki,&nbsp;A. Nagy,&nbsp;A. Bortolon,&nbsp;N. A. Pablant,&nbsp;A. Mollen,&nbsp;D. A. Gates,&nbsp;T. Morisaki","doi":"10.1007/s10894-025-00535-x","DOIUrl":"10.1007/s10894-025-00535-x","url":null,"abstract":"<div><p>The Impurity Powder Dropper (IPD) is a device capable of injecting controlled amounts of sub-millimetre powder into the plasma under the action of gravity. In 2019 the IPD was first installed on the Large Helical Device (LHD) in Japan, with the aim of improving the plasma performances through real time boronization and assessing the compatibility of this technique with steady state operation. Extensive series of experiments have been performed using the IPD, focused on the improvement of the plasma performance via low-Z powder injection and the understanding of the underlying physical phenomena. In this article, we review the experiments that took place in the period 2019-2024. The main results include the demonstration of the improvement of the wall conditions (reduction of intrinsic impurity content, wall recycling) both on a shot-to-shot basis and in real time. Furthermore, a reduced-turbulence improved confinement regime has been observed coincident with powder injection, resulting in an increase of the plasma temperature of the order of 25%, with enhancements that can reach up to 50% for ion temperature.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145613088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Energetic Particle Driven Modes and Interchange Modes in LHD Plasma Using the Gyro-Fluid Code FAR3d","authors":"J. Varela,&nbsp;K. Nagaoka,&nbsp;S. Ohdachi,&nbsp;K. Y. Watanabe,&nbsp;Y. Takemura,&nbsp;Y. Narushima,&nbsp;T. Tokuzawa,&nbsp;K. Tanaka,&nbsp;K. Ida,&nbsp;Y. Todo,&nbsp;M. Yoshinuma,&nbsp;R. Seki,&nbsp;K. Nagasaki,&nbsp;S. Kobayashi,&nbsp;P. Adulsiriswad,&nbsp;S. Yamamoto,&nbsp;D. A. Spong,&nbsp;L. Garcia,&nbsp;A. Cappa,&nbsp;Y. Ghai,&nbsp;J. Ortiz,&nbsp;W. A. Cooper,&nbsp;X. Du,&nbsp;S. Sharapov,&nbsp;F. L. Waelbroeck,&nbsp;B. Breizman,&nbsp;D. Zarzoso,&nbsp;C. Hidalgo,&nbsp;A. Azegami","doi":"10.1007/s10894-025-00527-x","DOIUrl":"10.1007/s10894-025-00527-x","url":null,"abstract":"<div><p>Energetic particles (EP) generated by the neutral beam injectors (NBI) in Large Helical Device (LHD) destabilize Alfvén Eigenmodes (AE) and energetic particle modes (EPM), leading to a reduction of the device performance. In particular, AE/EPM induce EP losses before thermalization that causes a lower plasma heating efficiency and damages to plasma facing components. Pressure gradient driven modes (PGDM) as interchange and ballooning modes also hamper the capability of LHD to confine the thermal plasma, limiting the maximum thermal plasma β of the discharge. The present study summarizes AE/EPM and PGDM characterization and optimization analysis performed in LHD plasma using the gyro-fluid code FAR3d. The linear and saturation phase of AE/EPM and PGDM leading to the destabilization of MHD burst, energetic-ion-driven resistive interchange mode (EIC) burst, internal collapse and saw-tooth like events are discussed. Optimization trends with respect to the NBI operation regime, magnetic field configuration, thermal plasma properties, external actuators and multiple EP populations effects are explored, comparing experiment and simulation data. Improved operation scenarios are identified and confirmed in dedicated experiments thanks to the minimization or avoidance of AE/EPM and PGDM along the discharge.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Damage To Injector Component Surfaces during Local Helicity Injection in Pegasus-III","authors":"Anupama S. Rajendra,&nbsp;Aaron C. Sontag,&nbsp;Kumar Sridharan,&nbsp; AlfredoNavarette,&nbsp;Stephanie J. Diem","doi":"10.1007/s10894-025-00528-w","DOIUrl":"10.1007/s10894-025-00528-w","url":null,"abstract":"<div><p>Pegasus III uses hollow-cathode arc plasma sources inside an injector assemblies to create electron beams to study tokamak plasma initiation via local helicity injection. These injector assemblies are exposed to intense power and particle fluxes from plasma material interactions that cause damage to injector components, limiting the injector lifetime. New injectors require surface conditioning to operate without sourcing current from the electrode surfaces and damaging the electrodes. Initial studies comparing surfaces of new molybdenum injector components to those at the end of their lifetime have been performed and found that significant melting is observed on electrode components most directly exposed to the injected plasma, while components exposed to the main chamber plasma show evidence of blistering.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10894-025-00528-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Public Perspectives on the Design of Fusion Energy Facilities: Evidence from a Participatory Design Workshop and Recommendations for Technology Developers","authors":"Nathan Kawamoto,&nbsp;Daniel Hoover,&nbsp;Jonathan Xie,&nbsp;Jacob Walters,&nbsp;Katie Snyder,&nbsp;Aditi Verma","doi":"10.1007/s10894-025-00522-2","DOIUrl":"10.1007/s10894-025-00522-2","url":null,"abstract":"<div><p>As fusion energy technologies approach demonstration and commercial deployment, understanding public perspectives on future fusion facilities will be critical for achieving social license. In a departure from the ‘decide-announce-defend’ approach typically used to site energy infrastructure, we develop a participatory design methodology for collaboratively designing fusion energy facilities with prospective host communities. We present here our findings from a participatory design workshop that brought together 22 community participants and 34 engineering students. Analysis of the textual and visual data from this workshop shows a range of design values and decision-making criteria with ‘integrity’ and ‘respect’ ranking highest among values and ‘economic benefits’ and ‘environmental protection/safety’ ranking highest among decision-making criteria. Salient design themes that emerge across the facility concepts include connecting the history and legacy of the community to the design of the facility, respect for nature, care for workers, transparency and access to the facility, and health and safety of the host community. Participants reported predominantly positive sentiments, expressing joy and surprise as the workshop progressed from learning about fusion to designing the hypothetical facility. Our findings suggest that carrying out participatory design in the early stages of technology development can invite and make concrete perspectives on public hopes and concerns, improve understanding of, and curiosity about, an emerging technology, build toward social license and inform context-specific development of future fusion energy facilities. Drawing on our findings and design process, we propose a prototype playbook for participatory design that will be developed further in future research. We recommend that fusion development teams (1) consider using participatory design approaches at multiple junctures throughout the fusion technology or facility development process, (2) build capacity to carry out such participatory engagements and (3) design standardized but adaptable technologies and facilities. We invite fusion technology developers to use and adapt our playbook for their own projects.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10894-025-00522-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145560933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aneutronic Fusion Study in Large Helical Device","authors":"Kunihiro Ogawa,&nbsp;Masaki Osakabe,&nbsp;Hideo Nuga,&nbsp;Mitsutaka Isobe","doi":"10.1007/s10894-025-00526-y","DOIUrl":"10.1007/s10894-025-00526-y","url":null,"abstract":"<div><p>A study of aneutronic fusion, which refers to fusion reactions that do not produce neutrons, has been conducted on the Large Helical Device (LHD). For the D–³He study, feasibility investigations of detecting charged fusion products have been performed. High-energy neutral beams, lost proton detectors, and gamma-ray detectors were planned for installation to validate the D–³He fusion reactions. Numerical calculations show that the expected D–³He fusion rate is 2.7 × 10¹⁶ s^-1 with most of the protons being lost immediately from the plasma. For the p–¹¹B study, the total alpha particle emission rate was estimated to be 10¹⁴ s^-1, and the loss points of alpha particle distribution were calculated. Based on these numerical simulations, we installed an alpha particle detector on a manipulator and positioned it at the bottom of the LHD. The time evolution of the alpha particle detection rate, measured by the detector, was found to be consistent with the predictions from the numerical simulations, demonstrating the first successful observation of the p–¹¹B reaction in a magnetic confinement system.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145510295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LHD Thomson Scattering Diagnostics","authors":"Ichihiro Yamada,&nbsp;Hisamichi Funaba,&nbsp;Takashi Minami,&nbsp;Ryo Yasuhara,&nbsp;Jong-ha Lee,&nbsp;Chunhua Liu,&nbsp;Yuan Huang","doi":"10.1007/s10894-025-00520-4","DOIUrl":"10.1007/s10894-025-00520-4","url":null,"abstract":"<div><p>Thomson scattering diagnostic systems are widely used to measure the local electron temperature and density of plasmas, which are one of the most important plasma parameters. The Large Helical Device (LHD) Thomson scattering system was designed and developed from 1991 to 1998, and has been in operation without any major problem since the LHD second experiment campaign in 1998. The LHD Thomson scattering system measures the pseudo-continuous time evolution of electron temperature and density profiles at 144 spatial points along the LHD major radius. The LHD Thomson scattering system can measure electron temperature and density spatially from the inner boundary to the outer boundary, and temporally from the birth to the destruction of LHD plasmas. The performance is still one of the best in the world. In this paper, we discuss improvements and newly obtained results of this system with emphasis on the results from 2010 to 2024.</p></div>","PeriodicalId":634,"journal":{"name":"Journal of Fusion Energy","volume":"44 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10894-025-00520-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145510692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}