Pub Date : 2026-01-09DOI: 10.1016/j.fusengdes.2025.115598
Troy Pederson , Himank Anand , Charlie Lasnier , Lennard Ceelen , Jun Ren , Keith Erickson , Ben Penaflor , John Ferron
In future tokamak reactors like ITER and the Fusion Pilot Plant (FPP), real-time feedback control of heat flux to the plasma-facing components (PFC) will be critical for steady-state operation. This work presents the first experimental demonstration of real-time divertor heat flux estimation with infrared thermography and feedback control with impurity seeding on the DIII-D tokamak. The flexible infrastructure of the Plasma Control System (PCS) on DIII-D makes this new capability possible. The PCS software runs on a gateway computer system, and five real-time compute nodes. An array of low latency streaming digitizers from d-TACQ Solutions connects to these real-time computers to collect and process data, and send commands to actuators during plasma discharges. This system handles the signal IO from the tokamak and allows the PCS to utilize the diagnostic data necessary to perform control in real-time. Feedback control on heat flux was accomplished by feeding infrared camera data from the “Infrared TV” (IRTV) camera to a custom-developed User Datagram Protocol (UDP) server. This server transmits infrared data to a newly developed PCS algorithm that estimates the heat flux to PFC. A proportional integral derivative (PID) controller minimizes the error between a heat flux reference and the real-time estimate by injecting nitrogen gas into the divertor.
{"title":"Preliminary proof-of-concept of real-time divertor heat flux control from infrared cameras with nitrogen injection in the DIII-D tokamak","authors":"Troy Pederson , Himank Anand , Charlie Lasnier , Lennard Ceelen , Jun Ren , Keith Erickson , Ben Penaflor , John Ferron","doi":"10.1016/j.fusengdes.2025.115598","DOIUrl":"10.1016/j.fusengdes.2025.115598","url":null,"abstract":"<div><div>In future tokamak reactors like ITER and the Fusion Pilot Plant (FPP), real-time feedback control of heat flux to the plasma-facing components (PFC) will be critical for steady-state operation. This work presents the first experimental demonstration of real-time divertor heat flux estimation with infrared thermography and feedback control with impurity seeding on the DIII-D tokamak. The flexible infrastructure of the Plasma Control System (PCS) on DIII-D makes this new capability possible. The PCS software runs on a gateway computer system, and five real-time compute nodes. An array of low latency streaming digitizers from <span>d</span>-TACQ Solutions connects to these real-time computers to collect and process data, and send commands to actuators during plasma discharges. This system handles the signal IO from the tokamak and allows the PCS to utilize the diagnostic data necessary to perform control in real-time. Feedback control on heat flux was accomplished by feeding infrared camera data from the “Infrared TV” (IRTV) camera to a custom-developed User Datagram Protocol (UDP) server. This server transmits infrared data to a newly developed PCS algorithm that estimates the heat flux to PFC. A proportional integral derivative (PID) controller minimizes the error between a heat flux reference and the real-time estimate by injecting nitrogen gas into the divertor.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115598"},"PeriodicalIF":2.0,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.fusengdes.2025.115612
Svitlana Rudchenko , Yiran Mao , Wolfgang Pantleon
Tungsten-based materials are considered as armor of plasma-facing components for future fusion reactors. To mitigate the brittleness of tungsten, tungsten fiber-reinforced tungsten composites (Wf/W) have been developed. Two types of Wf/W composites, with either continuous, aligned, potassium-doped tungsten wires in a dense tungsten matrix or randomly oriented, short fibers in a porous tungsten matrix are investigated. Both were fabricated using a powder metallurgical route facilitating field assisted sintering technology (FAST). Specimens are annealed at 1450 °C for different amounts of time up to two weeks to assess the thermal stability of the composites. Scanning electron microscopy and electron backscatter diffraction reveal major changes in the microstructure. After 4 hours of annealing initiation of recrystallization in the fibers concurrent to grain growth in the matrix is observed in both composites. Recrystallization commences at the outskirts of the fibers causing formation of a rim of small, recrystallized grains. Longer annealing increases the rim of recrystallized grains inwards into the fiber. After 3 days of annealing, all fibers are completely recrystallized, and the matrix is coarsened significantly by grain growth. While the short fibers can still be identified in the porous matrix after one week of annealing, matrix and continuous fibers cannot be distinguished any longer in the dense matrix. Short fibers with large, recrystallized grains can still be recognized after 2 weeks of annealing, while the porous matrix disintegrates by particle coarsening.
{"title":"Thermal stability of tungsten fiber-reinforced tungsten composites fabricated by powder metallurgy","authors":"Svitlana Rudchenko , Yiran Mao , Wolfgang Pantleon","doi":"10.1016/j.fusengdes.2025.115612","DOIUrl":"10.1016/j.fusengdes.2025.115612","url":null,"abstract":"<div><div>Tungsten-based materials are considered as armor of plasma-facing components for future fusion reactors. To mitigate the brittleness of tungsten, tungsten fiber-reinforced tungsten composites (W<sub>f</sub>/W) have been developed. Two types of W<sub>f</sub>/W composites, with either continuous, aligned, potassium-doped tungsten wires in a dense tungsten matrix or randomly oriented, short fibers in a porous tungsten matrix are investigated. Both were fabricated using a powder metallurgical route facilitating field assisted sintering technology (FAST). Specimens are annealed at 1450 °C for different amounts of time up to two weeks to assess the thermal stability of the composites. Scanning electron microscopy and electron backscatter diffraction reveal major changes in the microstructure. After 4 hours of annealing initiation of recrystallization in the fibers concurrent to grain growth in the matrix is observed in both composites. Recrystallization commences at the outskirts of the fibers causing formation of a rim of small, recrystallized grains. Longer annealing increases the rim of recrystallized grains inwards into the fiber. After 3 days of annealing, all fibers are completely recrystallized, and the matrix is coarsened significantly by grain growth. While the short fibers can still be identified in the porous matrix after one week of annealing, matrix and continuous fibers cannot be distinguished any longer in the dense matrix. Short fibers with large, recrystallized grains can still be recognized after 2 weeks of annealing, while the porous matrix disintegrates by particle coarsening.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115612"},"PeriodicalIF":2.0,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.fusengdes.2026.115625
Jiajing Hua, Puqiong Yang, Xianghui Yin, Yushan Zhou, Yulin Wang
CN-H1 is a three-cycle quasi-spiral symmetric star simulator. The timing control system needs to manage the starting, running and closing sequence of the coil power supply, heating system, diagnosis system and other subsystems in a unified way, and the clock error is required to be controlled within ±2 microseconds to ensure the coordinated operation of each subsystem. This paper designs and implements a distributed timing control system centered on virtual instruments in response to the strict requirements for high-precision and multi-channel timing control during the plasma discharge of stellarators. The system takes LabVIEW FPGA as the core execution module and realizes hardware-level parallel logic by using its graphical programming. Aiming at the complex timing logic of the stellarator, a hybrid programming model of "state machine - event" was designed to decompose the complex discharge process into configurable time segments, so as to achieve the purpose of real-time switching and dynamic adjustment of waveform segments during the experiment. The test results show that the nanosecond-level absolute delay of the system signal is completely transparent to millisecond-level applications. Meanwhile, the waveform synchronization error of any two channels of the system is better than 55ns. The system can stably generate complex timing waveforms with millisecond-level cycles, and the timing accuracy and synchronization performance significantly exceed those of conventional solutions. This design has the advantages of multi-channel output, simple operation and strong real-time performance. It fully meets the timing control requirements during the discharge of CN-H1 and has important engineering application value.
{"title":"Timing control system design of stellarator based on virtual instrument","authors":"Jiajing Hua, Puqiong Yang, Xianghui Yin, Yushan Zhou, Yulin Wang","doi":"10.1016/j.fusengdes.2026.115625","DOIUrl":"10.1016/j.fusengdes.2026.115625","url":null,"abstract":"<div><div>CN-H1 is a three-cycle quasi-spiral symmetric star simulator. The timing control system needs to manage the starting, running and closing sequence of the coil power supply, heating system, diagnosis system and other subsystems in a unified way, and the clock error is required to be controlled within ±2 microseconds to ensure the coordinated operation of each subsystem. This paper designs and implements a distributed timing control system centered on virtual instruments in response to the strict requirements for high-precision and multi-channel timing control during the plasma discharge of stellarators. The system takes LabVIEW FPGA as the core execution module and realizes hardware-level parallel logic by using its graphical programming. Aiming at the complex timing logic of the stellarator, a hybrid programming model of \"state machine - event\" was designed to decompose the complex discharge process into configurable time segments, so as to achieve the purpose of real-time switching and dynamic adjustment of waveform segments during the experiment. The test results show that the nanosecond-level absolute delay of the system signal is completely transparent to millisecond-level applications. Meanwhile, the waveform synchronization error of any two channels of the system is better than 55ns. The system can stably generate complex timing waveforms with millisecond-level cycles, and the timing accuracy and synchronization performance significantly exceed those of conventional solutions. This design has the advantages of multi-channel output, simple operation and strong real-time performance. It fully meets the timing control requirements during the discharge of CN-H1 and has important engineering application value.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115625"},"PeriodicalIF":2.0,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.fusengdes.2025.115601
Yuya Miyoshi, Yushiro Yamashita, Weixi Chen
Localized concentrations of plasma heat flux (comprising charged particles moving along magnetic field lines) can result in excessive thermal loads whose peak values may exceed several MW/m2, e.g. at the edges of blanket modules. Such conditions are undesirable and have motivated the development of heat load analysis methods, including magnetic field line tracing within the vacuum vessel (VV), as established in our previous work. In JA DEMO, reduced-activation ferritic martensitic steel is employed for the first wall (FW) due to its superior resistance to neutron irradiation. Here, the strong magnetic field in JA DEMO magnetizes the FW, thereby altering the magnetic field configuration in VV and affecting plasma equilibrium. This modified equilibrium, in turn, influences the magnetization vector in FW. Accurate prediction of magnetic field distribution in VV and the heat load distribution on the FW thus necessitates consideration of this mutual interaction between the magnetized FW and the plasma equilibrium. To address this, a computational code capable of evaluating the effect of FW magnetization under JA DEMO-like conditions is developed. The code iteratively computes a three-dimensional MHD equilibrium consistent with the magnetic field generated by the magnetized FW (). Subsequently, plasma heat flux and heat load distributions on the FW are calculated via the magnetic field line tracing. Although is relatively weak and it induces unnoticeable changes in plasma equilibrium, it significantly alters the heat load distribution compared to cases neglecting . In this research, three distinct patterns of influence are identified: (1) cumulative effect of weak altering field line trajectories, (2) strong modifying field line orbit, and (3) strong directly attracting field lines toward the FW. Future work will focus on identifying the specific conditions under which these effects become significant.
{"title":"Influence of magnetic fields generated by a magnetized ferritic first wall on surface heat loads from plasma heat flux along magnetic field lines","authors":"Yuya Miyoshi, Yushiro Yamashita, Weixi Chen","doi":"10.1016/j.fusengdes.2025.115601","DOIUrl":"10.1016/j.fusengdes.2025.115601","url":null,"abstract":"<div><div>Localized concentrations of plasma heat flux (comprising charged particles moving along magnetic field lines) can result in excessive thermal loads whose peak values may exceed several MW/m<sup>2</sup>, e.g. at the edges of blanket modules. Such conditions are undesirable and have motivated the development of heat load analysis methods, including magnetic field line tracing within the vacuum vessel (VV), as established in our previous work. In JA DEMO, reduced-activation ferritic martensitic steel is employed for the first wall (FW) due to its superior resistance to neutron irradiation. Here, the strong magnetic field in JA DEMO magnetizes the FW, thereby altering the magnetic field configuration in VV and affecting plasma equilibrium. This modified equilibrium, in turn, influences the magnetization vector in FW. Accurate prediction of magnetic field distribution in VV and the heat load distribution on the FW thus necessitates consideration of this mutual interaction between the magnetized FW and the plasma equilibrium. To address this, a computational code capable of evaluating the effect of FW magnetization under JA DEMO-like conditions is developed. The code iteratively computes a three-dimensional MHD equilibrium consistent with the magnetic field generated by the magnetized FW (<span><math><msub><mover><mi>B</mi><mo>→</mo></mover><mi>m</mi></msub></math></span>). Subsequently, plasma heat flux and heat load distributions on the FW are calculated via the magnetic field line tracing. Although <span><math><msub><mover><mi>B</mi><mo>→</mo></mover><mi>m</mi></msub></math></span> is relatively weak and it induces unnoticeable changes in plasma equilibrium, it significantly alters the heat load distribution compared to cases neglecting <span><math><msub><mover><mi>B</mi><mo>→</mo></mover><mi>m</mi></msub></math></span>. In this research, three distinct patterns of <span><math><msub><mover><mi>B</mi><mo>→</mo></mover><mi>m</mi></msub></math></span> influence are identified: (1) cumulative effect of weak <span><math><msub><mover><mi>B</mi><mo>→</mo></mover><mi>m</mi></msub></math></span> altering field line trajectories, (2) strong <span><math><msub><mover><mi>B</mi><mo>→</mo></mover><mi>m</mi></msub></math></span> modifying field line orbit, and (3) strong <span><math><msub><mover><mi>B</mi><mo>→</mo></mover><mi>m</mi></msub></math></span> directly attracting field lines toward the FW. Future work will focus on identifying the specific conditions under which these effects become significant.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115601"},"PeriodicalIF":2.0,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The measurement of neutron yield plays a critical role in fusion power assessment and safety control for tokamak devices. This paper presents a comprehensive performance evaluation and system design of the neutron yield measurement system for the HL-3 tokamak, based on neutronic modeling with MCNP. The reliability of the model was validated against data from in-situ calibration experiments, showing good agreement between simulated and measured absolute detector efficiencies. The system comprises eight fission chambers, designed to cover a neutron yield range from 1010 to 1019n/s for both DD and DT discharge scenarios. Simulations were performed to analyze the effects of moderator material, reflected neutron contribution, and plasma displacement on measurement performance. The results indicate that polyethylene as a moderator provides a sufficiently flat sensitivity. The contribution of neutrons reflected by the bio-shielding wall to the detector sensitivity was found to be non-negligible. Plasma displacement has a minimal impact on detector sensitivity and does not significantly alter the system measurement range. Ultimately, the performance of the HL-3 neutron yield measurement system fully meets the physics design requirements and will provide reliable support for neutron yield and fusion power measurement during HL-3 experiments.
{"title":"Neutronic modeling and physical analysis of the neutron yield measurement system for the HL-3 Tokamak","authors":"Zuowei Wen, Lei Feng, Guoliang Yuan, Wei Zhao, Jiawei Shi, Fengzhao Shen","doi":"10.1016/j.fusengdes.2026.115614","DOIUrl":"10.1016/j.fusengdes.2026.115614","url":null,"abstract":"<div><div>The measurement of neutron yield plays a critical role in fusion power assessment and safety control for tokamak devices. This paper presents a comprehensive performance evaluation and system design of the neutron yield measurement system for the HL-3 tokamak, based on neutronic modeling with MCNP. The reliability of the model was validated against data from in-situ calibration experiments, showing good agreement between simulated and measured absolute detector efficiencies. The system comprises eight fission chambers, designed to cover a neutron yield range from 10<sup>10</sup> to 10<sup>19</sup>n/s for both DD and DT discharge scenarios. Simulations were performed to analyze the effects of moderator material, reflected neutron contribution, and plasma displacement on measurement performance. The results indicate that polyethylene as a moderator provides a sufficiently flat sensitivity. The contribution of neutrons reflected by the bio-shielding wall to the detector sensitivity was found to be non-negligible. Plasma displacement has a minimal impact on detector sensitivity and does not significantly alter the system measurement range. Ultimately, the performance of the HL-3 neutron yield measurement system fully meets the physics design requirements and will provide reliable support for neutron yield and fusion power measurement during HL-3 experiments.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115614"},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-06DOI: 10.1016/j.fusengdes.2025.115602
B. Kool , M. Lennholm , A. Parrott , P.A. Figueiredo , G.L. Derks , O.P. Bardsley , M. Lord , A. Cureton , S.S. Henderson , N.J. Conway , J. Lovell , T.A. Wijkamp , N. Lonigro , S.P. Kobussen , L. Ceelen , K. Verhaegh , M. van Berkel , STEP team , MAST-U team , EUROfusion Tokamak Exploitation Team
This work explores the challenges and opportunities for power exhaust control in STEP, informed by dedicated MAST-U experiments. The STEP system primarily relies on hydrogenic and argon gas injection into the divertors, compensating for transients originating in the plasma core. Fast transients (10 Hz) that evolve too quickly for actuators to compensate must be absorbed passively; the enhanced transient buffering of the foreseen long-legged divertor provides a clear advantage over conventional geometries, as demonstrated in the MAST-U Super-X divertor. Experiments further indicate that STEP’s tight divertor baffling enables near-independent control of the upper and lower divertors. The most challenging transients are expected from power-sharing fluctuations, as MAST-U experiments observed extremely fast dynamics. Fluctuations from core pellet fuelling remain relatively benign due to the small pellet size according to simulations. Exhaust control in a reactor like STEP requires an integrated approach befitting its machine-critical nature. A predictive control element, integrated with core plasma control, allows pre-emptive preparation of the divertor for incoming transients. An observer-based diagnostic approach is foreseen to monitor the divertor in the challenging reactor environment, supported by an extended diagnostic set in the non-nuclear phase to validate the required dynamic models.
{"title":"From MAST-U to STEP: Power exhaust control challenges and opportunities","authors":"B. Kool , M. Lennholm , A. Parrott , P.A. Figueiredo , G.L. Derks , O.P. Bardsley , M. Lord , A. Cureton , S.S. Henderson , N.J. Conway , J. Lovell , T.A. Wijkamp , N. Lonigro , S.P. Kobussen , L. Ceelen , K. Verhaegh , M. van Berkel , STEP team , MAST-U team , EUROfusion Tokamak Exploitation Team","doi":"10.1016/j.fusengdes.2025.115602","DOIUrl":"10.1016/j.fusengdes.2025.115602","url":null,"abstract":"<div><div>This work explores the challenges and opportunities for power exhaust control in STEP, informed by dedicated MAST-U experiments. The STEP system primarily relies on hydrogenic and argon gas injection into the divertors, compensating for transients originating in the plasma core. Fast transients (<span><math><mo>></mo></math></span>10 Hz) that evolve too quickly for actuators to compensate must be absorbed passively; the enhanced transient buffering of the foreseen long-legged divertor provides a clear advantage over conventional geometries, as demonstrated in the MAST-U Super-X divertor. Experiments further indicate that STEP’s tight divertor baffling enables near-independent control of the upper and lower divertors. The most challenging transients are expected from power-sharing fluctuations, as MAST-U experiments observed extremely fast dynamics. Fluctuations from core pellet fuelling remain relatively benign due to the small pellet size according to simulations. Exhaust control in a reactor like STEP requires an integrated approach befitting its machine-critical nature. A predictive control element, integrated with core plasma control, allows pre-emptive preparation of the divertor for incoming transients. An observer-based diagnostic approach is foreseen to monitor the divertor in the challenging reactor environment, supported by an extended diagnostic set in the non-nuclear phase to validate the required dynamic models.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115602"},"PeriodicalIF":2.0,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1016/j.fusengdes.2025.115608
S. Del Nero , P. Fanelli , V. Prost , F.A. Volpe
The performance of high-field magnets is increasingly constrained not by the limits of High-Temperature Superconducting materials, but by the structural systems needed to withstand the intense Electro-Magnetic forces they produce. In response to this challenge, this work presents a design-driven methodology for optimizing the reinforcement structures of 52 cm bore wide HTS magnets under development at Renaissance Fusion, aimed at achieving magnetic fields up to 10 T on the plasma axis. A custom Topology Optimization tool, based on the Solid Isotropic Material Penalization method and implemented entirely in PyMAPDL, was employed to guide the mechanical design of the magnet reinforcements. Starting from a large design domain (11.3 tons per sector), Topology Optimization with varying volume fractions produced lightweight structures, down to 3.93 tons, that meet strict mechanical constraints on magnet displacement (1 mm), magnet strain (0.5%) and global stress (800 MPa). Then, a second optimization stage using extrusion constraints methodologies was employed to further optimize the structure while ensuring manufacturability. Recurring features from these runs informed the development of a parametric model, enabling further refinement and a final mass of 1.20 t. The final structure, segmented into sub-components for a feasible assembly procedure, retained the required mechanical performance while ensuring ease of manufacturing using conventional processes. This magnet design demonstrate the applicability and benefits of our multi-stage constrained topology optimization method for advancing the structural design of high-field and compact stellarators.
{"title":"Topology Optimization of a 10 T, 52 cm bore stellarator magnet structure","authors":"S. Del Nero , P. Fanelli , V. Prost , F.A. Volpe","doi":"10.1016/j.fusengdes.2025.115608","DOIUrl":"10.1016/j.fusengdes.2025.115608","url":null,"abstract":"<div><div>The performance of high-field magnets is increasingly constrained not by the limits of High-Temperature Superconducting materials, but by the structural systems needed to withstand the intense Electro-Magnetic forces they produce. In response to this challenge, this work presents a design-driven methodology for optimizing the reinforcement structures of 52 cm bore wide HTS magnets under development at Renaissance Fusion, aimed at achieving magnetic fields up to 10 T on the plasma axis. A custom Topology Optimization tool, based on the Solid Isotropic Material Penalization method and implemented entirely in PyMAPDL, was employed to guide the mechanical design of the magnet reinforcements. Starting from a large design domain (<span><math><mo>∼</mo></math></span>11.3 tons per sector), Topology Optimization with varying volume fractions produced lightweight structures, down to 3.93 tons, that meet strict mechanical constraints on magnet displacement (<span><math><mo><</mo></math></span>1 mm), magnet strain (<span><math><mo><</mo></math></span>0.5%) and global stress (<span><math><mo><</mo></math></span>800 MPa). Then, a second optimization stage using extrusion constraints methodologies was employed to further optimize the structure while ensuring manufacturability. Recurring features from these runs informed the development of a parametric model, enabling further refinement and a final mass of 1.20 t. The final structure, segmented into sub-components for a feasible assembly procedure, retained the required mechanical performance while ensuring ease of manufacturing using conventional processes. This magnet design demonstrate the applicability and benefits of our multi-stage constrained topology optimization method for advancing the structural design of high-field and compact stellarators.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115608"},"PeriodicalIF":2.0,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1016/j.fusengdes.2025.115611
Jinpeng Zhang , Lihua Guo , Guoqiang Wang , Jun Lin , Linyuan Lu , Jinwei Zhan
The effect of sintering temperature on the microstructural evolution and densification behaviors of W14Re2 (with a Re atomic ratio of 12.50 % and a mass ratio of 12.64 %) was explored for the first time utilizing spark plasma sintering (SPS) technology. The results reveal that Re is uniformly dispersed within the W matrix following high-energy ball milling. 1300 °C serves as a critical threshold for the microstructural transformation of W14Re2 alloy, during which the grain morphology evolves from nearly spherical to equiaxed. 1400 °C marks a pivotal temperature point for the densification transition of W14Re2, where the sample surface transforms from being porous and loose to highly dense. Overall, as the temperature rises, the grain size demonstrates a gradual increasing tendency. Specifically, the average W grain size attains approximately 1 μm at 1700 °C, which corresponds to a theoretical density of 97.47 %. Furthermore, the two phases exhibit an alternating peak-and-valley elemental concentration profile along the interface. The HRTEM reveals uniformly distributed diffraction spots with alternating intensities at the two-phase interface. These spots oscillate asymmetrically around the original lattice positions, suggesting a twin-like structural feature. This phenomenon can be attributed to Re doping-induced lattice distortion in the W matrix at elevated temperatures, coupled with interfacial interactions that facilitate solid solution formation between the phases. This study offers a preliminary investigation into the sintering properties of the W14Re2 alloy and is anticipated to establish a groundwork for facilitating further optimized preparation of W-Re alloys.
{"title":"Microstructural evolution and densification behaviors of W14Re2 alloy produced at different temperature by spark plasma sintering","authors":"Jinpeng Zhang , Lihua Guo , Guoqiang Wang , Jun Lin , Linyuan Lu , Jinwei Zhan","doi":"10.1016/j.fusengdes.2025.115611","DOIUrl":"10.1016/j.fusengdes.2025.115611","url":null,"abstract":"<div><div>The effect of sintering temperature on the microstructural evolution and densification behaviors of W<sub>14</sub>Re<sub>2</sub> (with a Re atomic ratio of 12.50 % and a mass ratio of 12.64 %) was explored for the first time utilizing spark plasma sintering (SPS) technology. The results reveal that Re is uniformly dispersed within the W matrix following high-energy ball milling. 1300 °C serves as a critical threshold for the microstructural transformation of W<sub>14</sub>Re<sub>2</sub> alloy, during which the grain morphology evolves from nearly spherical to equiaxed. 1400 °C marks a pivotal temperature point for the densification transition of W<sub>14</sub>Re<sub>2</sub>, where the sample surface transforms from being porous and loose to highly dense. Overall, as the temperature rises, the grain size demonstrates a gradual increasing tendency. Specifically, the average W grain size attains approximately 1 μm at 1700 °C, which corresponds to a theoretical density of 97.47 %. Furthermore, the two phases exhibit an alternating peak-and-valley elemental concentration profile along the interface. The HRTEM reveals uniformly distributed diffraction spots with alternating intensities at the two-phase interface. These spots oscillate asymmetrically around the original lattice positions, suggesting a twin-like structural feature. This phenomenon can be attributed to Re doping-induced lattice distortion in the W matrix at elevated temperatures, coupled with interfacial interactions that facilitate solid solution formation between the phases. This study offers a preliminary investigation into the sintering properties of the W<sub>14</sub>Re<sub>2</sub> alloy and is anticipated to establish a groundwork for facilitating further optimized preparation of W-Re alloys.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115611"},"PeriodicalIF":2.0,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-31DOI: 10.1016/j.fusengdes.2025.115609
M.Y. He , J.M. Gao , X.Q. Ji , T.F. Sun , A. Wang , B.T. Cui , H.L. Du , J.X. Li , L. Liu , G.Z. Hao
The plasma boundary has been reconstructed using integrated multispectral optical imaging systems on the HL-3 tokamak, with particular emphasis on the divertor region. In addition to the mid-plane visible imaging system, which is commonly used to reconstruct the main plasma boundary, a new lower divertor visible and infrared imaging system has been developed to reconstruct the locations of the X-point and the strike points. It increases the accuracy of reconstructed plasma boundary, achieving precision of approximately 10 mm. Simulation results demonstrate that the averaged reconstructed error of the optical boundary is within a few millimeters. Finally, the reconstructed optical plasma boundary shows strong potential for applications in plasma diagnostics and equilibrium analysis.
{"title":"Optical boundary reconstruction with visible/infrared integrated imaging systems on the HL-3 tokamak","authors":"M.Y. He , J.M. Gao , X.Q. Ji , T.F. Sun , A. Wang , B.T. Cui , H.L. Du , J.X. Li , L. Liu , G.Z. Hao","doi":"10.1016/j.fusengdes.2025.115609","DOIUrl":"10.1016/j.fusengdes.2025.115609","url":null,"abstract":"<div><div>The plasma boundary has been reconstructed using integrated multispectral optical imaging systems on the HL-3 tokamak, with particular emphasis on the divertor region. In addition to the mid-plane visible imaging system, which is commonly used to reconstruct the main plasma boundary, a new lower divertor visible and infrared imaging system has been developed to reconstruct the locations of the X-point and the strike points. It increases the accuracy of reconstructed plasma boundary, achieving precision of approximately 10 mm. Simulation results demonstrate that the averaged reconstructed error of the optical boundary is within a few millimeters. Finally, the reconstructed optical plasma boundary shows strong potential for applications in plasma diagnostics and equilibrium analysis.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115609"},"PeriodicalIF":2.0,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.fusengdes.2025.115607
Kaiyang Yi , Zhihui Huang , Weice Wang , Jun Cheng , Na Wu , Yu He , Wei Zhao , Lin Nie , Longwen Yan , Guoliang Xiao , Zhongbing Shi , Xiaoquan Ji , Wulyu Zhong
This paper introduces the mid-plane fast reciprocating probe (FRP) system in the HL-3 tokamak. Unlike traditional pneumatic cylinder or servo motor drives, this system achieves fast movement through the operation of a linear motor and a counterweight cabinet. The counterweight cabinet is chosen to balance the atmospheric pressure for the first time, without requiring a large linear motor with high output torque. As a result, the system takes up less space and has high speed, high acceleration, long stroke length, and adjustable movement distance. The front of this system can accommodate various compound probes with a maximum pin number of 19. At present, this system has been put into operation in the HL-3 tokamak, and preliminary experimental results confirm the novel design.
{"title":"Fast reciprocating probe system with synergistic operation of a small linear motor and a counterweight cabinet on HL-3","authors":"Kaiyang Yi , Zhihui Huang , Weice Wang , Jun Cheng , Na Wu , Yu He , Wei Zhao , Lin Nie , Longwen Yan , Guoliang Xiao , Zhongbing Shi , Xiaoquan Ji , Wulyu Zhong","doi":"10.1016/j.fusengdes.2025.115607","DOIUrl":"10.1016/j.fusengdes.2025.115607","url":null,"abstract":"<div><div>This paper introduces the mid-plane fast reciprocating probe (FRP) system in the HL-3 tokamak. Unlike traditional pneumatic cylinder or servo motor drives, this system achieves fast movement through the operation of a linear motor and a counterweight cabinet. The counterweight cabinet is chosen to balance the atmospheric pressure for the first time, without requiring a large linear motor with high output torque. As a result, the system takes up less space and has high speed, high acceleration, long stroke length, and adjustable movement distance. The front of this system can accommodate various compound probes with a maximum pin number of 19. At present, this system has been put into operation in the HL-3 tokamak, and preliminary experimental results confirm the novel design.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"224 ","pages":"Article 115607"},"PeriodicalIF":2.0,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号