Table of Content

15 March 2026, Volume 46 Issue 1

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Nuclear Fusion Engineering

Microstructure and properties of W-Ta alloys fabricated by hot-press sintering and high energy rate forging

WANG Zi-jie, REN Song-jia, FENG Fan, WANG Jian-bao, ZHAO Chen-xi, FENG Ren-chao, LI Xue, QIANG Jian-bing, WANG Ying-min, LIAN You-yun, LIU Xiang

2026, 46(1):  1-8.  DOI: 10.16568/j.0254-6086.202601001

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Tungsten (W) based composite powders with Tantalum (Ta) contents of 1.0 wt% and 5.0 wt% were prepared by two-step ball milling method, and then W-Ta alloys were prepared by hot press sintering and high energy rate forging, which were subjected to microstructural analysis and property characterization. The results show that the addition of Ta can significantly increase the Vickers hardness, recrystallization temperature,and tensile strength of wrought W. With the increase of Ta content, the grain of W-Ta alloy is refined, and the hardness of sintered and wrought state is higher. The 1.0 wt% Ta alloy combines excellent mechanical properties,high recrystallization temperature and high thermal conductivity. The plasticity of W is severely degraded by the too high Ta content.


Ablation mechanism analysis and structural optimization of central column limiter in EXL-50 device

JIA Peng-mei, YANG Yuan-ming

2026, 46(1):  9-14.  DOI: 10.16568/j.0254-6086.202601002

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ENN’s independently developed EXL-50, China’s first medium-scale spherical tokamak for exploratory experiments on commercial fusion power generation, encountered ablation of the copper-plated tungsten central column limiter during physical experiments, which is highly detrimental to stable plasma operation. Studies reveal that this phenomenon stems from two primary causes: First, installation deviations between the limiter and both the geometric axis of the central column and the magnetic field line axis expose the limiter to the strike zone of plasma magnetic field lines, subjecting it to meet intense thermal load impacts. Second,the limited bonding strength between the tungsten coating and copper substrate of the copper-plated tungsten limiter leads to ablation and spalling under repeated thermal load cycles. To fundamentally address the ablation issue, structural optimization and material upgrade of the limiter were implemented, accompanied by thermal-solid coupling field simulations under baking conditions. Results show that the optimized central column limiter meets requirements in both thermal performance and deformation control. Experimental verification confirms that the optimized structure exhibits no thermal spots or ablation phenomena.


Numerical simulation of welding deformation for ITER first wall outlet pipes

ZHU Xiao-bo, GOU Jun, HU Dan, ZHOU Yi, QIU Rong, LI Jia-lin, WU Jing, FAN Xiao-ping, CHEN Ji-ming, WANG Ping-huai

2026, 46(1):  15-21.  DOI: 10.16568/j.0254-6086.202601003

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The internal-bore girth welds of the inlet/outlet coolant pipes on the ITER First Wall are located at structurally weak fulcrums; welding-induced distortion is therefore amplified, producing misalignment between the as-built pipe ends and the pre-installed stubs, and preventing final closure welding in situ. A thermo-elasto-plastic model incorporating the robotic pose concept was developed in SYSWELD to simulate bore-weld distortion of the outlet pipe and to quantify the six-degree-of-freedom displacement of the bent-pipe interface. The results demonstrate that the arc-strike location decisively influences the post-weld position and orientation of the assembly end, as well as the force and torque required for corrective alignment during installation. This sensitivity is traced to the circumferential dependence of axial shrinkage distribution, which is the direct cause of the observed differences. Comparative analyses indicate that deliberate selection of the arc-start position together with a dimensional allowance equal to the predicted weld distortion effectively reduces both welding-induced deformation and the assembly loads encountered in the field.


Preliminary design of bolometer diagnostic electronic system for magnetic confinement fusion device

ZHANG Xiao-dong, , CAO Hong-rui, , LIU Shi-xing, ZHAO Jin-long, LI Qiang, DUAN Yan-min, LIN Shi-yao

2026, 46(1):  22-28.  DOI: 10.16568/j.0254-6086.202601004

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The bolometer diagnosis on magnetic confinement fusion device mainly measures the total radiation power and radiation power density distribution of plasma, which is of great significance for studying the plasma operation process such as energy balance, confinement and transport. In this paper, a set of bolometer thermal electronics system is designed for metal film resistance bolometer detector. The system is mainly composed of front-end electronic circuit board and ARM embedded main control part. Among them, the electronics part is divided into three modules according to the function: carrier signal generation, amplitude modulation signal processing, synchronous demodulation and filtering, and the design and function verification.Compared with the traditional bolometer, it improves the integration, can realize multi-channel data acquisition in a limited space, and enhances the convenience and reliability of use. Experiments show that the overall response time of the electronic system and the detector is about 180 ms, the linear correlation coefficient R of the electronic system is 0.99993, and the linearity of the system is good. The response trend of the system to radiant heat is basically the same as that of the original system, which shows the rationality of the system design and lays an important foundation for subsequent improvement.


The design of microwave exciter system for LHCD system on HL-3 tokamak

LIANG Jun, LU Bo, BAI Xing-yu, ZENG Hao, CHEN Ya-li, WANG Chao, FENG Kun, WANG Jie-qiong, ZUO Lan, MA Yue-xin, XU Ling-fei

2026, 46(1):  29-35.  DOI: 10.16568/j.0254-6086.202601005

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In order to improve the efficiency of lower hybrid current drive (LHCD) system on HL-3 tokamak,new functions such as power real-time control and phase real-time feedback are needed in the new microwave exciter. The DDS and frequency mixing scheme are used in the microwave exciter to attain low phase noise, high frequency stability and high spurious rejection ratio of the microwave output signal in a certain frequency band.The phase real-time feedback control with response time less than 50 μs is realized by using digital-analog phase shifter + FPGA. Real-time power control with response time less than 50 μs is achieved using a digital-analog attenuator + FPGA. Based on the above design ideas, the design of microwave excitation source for LHCD system on HL-3 tokamak is completed.

Research and application of a numerical method for magnetization force calculation of the fusion reactor blankets

DONG Hai-jie, LIU Xiang, DUAN Xu-ru, WU Xing-hua, WANG Xiao-yu

2026, 46(1):  36-42.  DOI: 10.16568/j.0254-6086.202601006

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It is of great significance to accurately evaluate the magnetization force and Lorentz force etc.electromagnetic loads of the vacuum vessel, divertor and blanket of tokamak fusion reactors to optimize the design and to ensure the structural safety. A numerical method for magnetization force calculation is introduced utilizing the Maxwell stress tensor approach based on the edge element provided by ANSYS. This method can calculate not only the total magnetization force, but also can obtain the equivalent distribution of the loads on the studying object. The results show that the force calculated by this method can be affected by the size and deformation of the elements. Fortunately, if the force is output only through the corner nodes, the influence is negligible and the total force agrees well with the analytical one. Moreover, the qualitative analysis shows that the result of magnetization force distribution is consistent with the relevant theory of electromagnetism. This numerical method can be applied to the magnetization force analysis and subsequent electromagnetic-structural coupling analysis of the blankets in fusion reactors.




Welding process and performance analysis of heterogeneous steel for fusion reactor blanket

FU Yong-gan , LIU Jin , WANG Hu , WEI Jing , WANG Wei-hua

2026, 46(1):  43-49.  DOI: 10.16568/j.0254-6086.202601007

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I In order to connect low-activation ferritic/martensitic (RAFM) steel and 316LN austenitic stainless steel, two different methods of laser welding and tungsten inert gas shielded (TIG) one were selected to weld the test parts, and the quality of the welded parts was tested. Phase composition and microstructure characterization of the welding seam were performed by XRD, metallographic microscope, and SEM analysis of the micro-zone of the welds. The mechanical properties of the welds were tested using a Vickers hardness tester and an electronic universal testing machine. The results show that both welding methods have no macroscopic defects, however micro-porosity and carbides were observed under SEM. The tensile strength of the laser weldment is 597.32 MPa, and the elongation of the fracture surface is 39.16%. The tensile strength of the TIG weldment is 603.19 MPa, and the elongation of the fracture surface is 33.72%. Combined with the welding process and the comprehensive comparison of the performance of the weldments, laser welding is recommended as the preferred option in the field welding scheme for blanket components.




Design and test of nonlinear resistor demagnetization of 300 MVA motor generator

SHI Xiao-fei, PENG Jian-fei, WANG Hai-bing, LIAO Chao

2026, 46(1):  50-56.  DOI: 10.16568/j.0254-6086.202601008

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In order to meet the pulse power supply needs of HL-3 large-scale tokamak , the domestic first 300 MVA vertical six-phase high-power motor generator (MG) was developed. Because its discharge time is as short as seconds and its power supply parameters are high, in order to ensure the safe operation of the units and tokamak, a rapid demagnetization system had been developed for the MG. The design of the system is based on zinc oxide nonlinear demagnetization resistor, including rotor demagnetization and over-voltage protection devices, DC side peak over-voltage absorbers, non-full-phase and large slip asynchronous operation protectors.The components of the demagnetization device were selected, their parameters were determined, and the dielectric properties and overvoltage protection characteristics of the device were tested. The test results showed that the MG rapid demagnetization system can meet its design requirements.

Design of fuse protection of pulse capacitor for KTX power supply

FENG Hu-lin , WANG Deng-hui , HE Bao-can , DONG Yu-qi, , PAN Sheng-min , LU Jing , WU Ya-nan

2026, 46(1):  57-62.  DOI: 10.16568/j.0254-6086.202601009

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The power supply system of the Keda Torus eXperiment (KTX) uses pulse capacitor banks for energy storing, providing instantaneous power of exceeding 200 MW. Therefore, short circuit protection of pulse capacitors is crucial, the design and reliability test of fuses is key to pulse capacitor protection. As the cost of protection equipment of KTX power supply is high, a low-cost fuse is studied independently to protect the safety of the capacitor bank. The cross-sectional area of the fuse is determined based on the temperature rise requirements. The length of the fuse is confirmed through the minimum voltage drop requirement of the pulse capacitor and the minimum fusing critical energy of the fuse. The simulation and experimental verification are conducted, and the safety and reliability of the fuse development is validated during the long-term operation of KTX power supply.

Design and simulation of a three-stub matching network for a high-power transmitter amplifier

TANG Liang , ZHANG Ke-qing , ZHU Guang-hui , QIN Cheng-ming , ZHANG Xin-jun , MAO Yu-zhou , YUAN Shuai , WANG Lei , LIU Lu-nan , YANG Hua , ZHANG Wei , ZHANG Kai , LI Liang-liang

2026, 46(1):  63-70.  DOI: 10.16568/j.0254-6086.202601010

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To effectively match the input impedance of the final stage tube to the characteristic impedance transmission line, it is necessary to develop a new wideband matching device applied to high-power tetrode amplifiers in transmitters for ion cyclotron resonance heating, ranging from hundreds of kilowatts to megawatts. A comprehensive approach combining RF transmission theory, circuit analysis, and 3D finite element simulation is employed to determine the optimal length of the short-circuited stubs at various operating frequencies. Additionally, an deep analysis of load impedance sensitivity is conducted. This research reveals discrepancies and limitations between theoretical calculations and 3D simulations, as well as experimental results, highlighting the importance of comprehensive consideration in the design of high-power transmitters.

Design of RISC-V microcontroller for high-voltage power supply control systems

WANG Jing, LI Qing, CHEN Jun-hong, MAO Xiao-hui, XIA Yu-yang

2026, 46(1):  71-76.  DOI: 10.16568/j.0254-6086.202601011

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In the auxiliary heating systems of tokamak plasmas, the continuous increase of high-voltage power supplies has led to more stringent requirements for real-time transmission and data reliability of high-voltage power control systems. To ensure the stability and data accuracy of the high-voltage power control system of the HL-3 tokamak, this paper adopts the Chisel language to design and develop a RISC-V microcontroller for a high-voltage power control system. The design implements a single-issue, five-stage pipeline processor using pipeline-related technologies such as data forwarding and branch prediction. It has passed tests including CPU tests and the Median test suite, and can perform operational tests of the RT-Thread embedded real-time operating system. Under power-constrained conditions, this RISC-V microcontroller can perform data processing efficiently, meeting the open-source, customizable design and reliability of controllable nuclear fusion for embedded processors.




Analysis on electric field of dry-type transformer and modules in PSM high voltage power supply

FAN Zhen-yuan, LI Qing, MAO Xiao-hui

2026, 46(1):  77-82.  DOI: 10.16568/j.0254-6086.202601012

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Based on the design of the ion cyclotron high-voltage power supply for the China Fusion Engineering Test Reactor (CFETR), an electric field analysis was conducted on the dry-type multi-winding transformer and power supply module to verify the insulation safety of the design and provide recommendations for potential weak points in the system. Firstly, a finite element analysis software was employed to perform steady-state electric field calculations for the dry-type transformer. The results confirmed the insulation safety of the transformer under normal operating conditions, while also revealing non-uniform electric field distribution around the spacer blocks, suggesting that their geometry should be optimized. Subsequently, an equivalent circuit method was used to analyze the transient response of the transformer under overvoltage impulse conditions,yielding the corresponding electric field distribution. The results showed that the maximum electric field intensity in the main air channel was relatively high; this could be mitigated by adjusting the dimensions of the transformer’s insulation structure. For the power supply module, the influence of parasitic capacitance was taken into account, and the electric field distribution around the mounting brackets was calculated and simulated. The simulation showed that the highest electric field occurred at the edges where the sharp corners of the power module meet the surrounding air, but this peak field strength remained below the dielectric breakdown strength of air.

Plasma Physics

Three-dimensional numerical simulation of temperature distribution of RF-DC hybrid thermal plasma

ZHOU Zhi-wei , SU Yi , FENG Rui , TAN Chong , ZHU Hai-long

2026, 46(1):  83-88.  DOI: 10.16568/j.0254-6086.202601013

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Plasma has the characteristics of high temperature, high enthalpy and high chemical activity. It is an ideal preparation method in the fields of micro-nano material preparation and plasma spraying. However, the discharge area of single plasma torch is small, and the high temperature area of plasma is limited, which makes the residence time of material particles in the high temperature area of plasma short, limits the heating and melting effect of material particles, and affects the preparation efficiency and coating performance. For this reason, we designed an RF-DC hybrid plasma torch. Using the secondary development of FLUENT software, a user-defined function C++ program for calculating the hybrid plasma was written, and the physical field distribution in the hybrid plasma torch was calculated. The results show that the hybrid plasma torch stably extends the plasma length and increases the residence time of the material particles in the high temperature region of the plasma, thereby optimizing the heating and melting process of the material particles. This provides theoretical guidance for optimizing and upgrading plasma generators and their applications in industry.

Linear properties of energetic particle modes with m/n=1/1 driven by passing fast ions

GUO Wen-tao , WANG Xian-qu , SU Xiang , XU Yu-hong , CHENG Jun , LIU Hai-feng , HUANG Jie , ZHANG Xin , LIU Hai , TANG Chang-jian

2026, 46(1):  89-96.  DOI: 10.16568/j.0254-6086.202601014

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The study of magnetohydrodynamic instabilities driven by fast particles has been a prominent focus in magnetic confinement fusion research. The effects of the fast ion beta, local magnetic shear, core safety factor and initial velocity of fast ions on the linear instability of energetic particle modes are numerically analyzed using the experimental parameters of HL-2A tokamak. It is shown that the fast ion beta enough large will drive m/n=1/1 instability, and the mode structure is similar to the kink mode or the interchange mode (depending on the plasma parameters), where, m and n are the poloidal and toroidal mode number,respectively. When the magnetic shear is weak, the mode growth rate is less dependent on the fast ion beta, and the mode is more easily excited.The initial velocity of the fast ion is directly proportional to the growth rate and frequency of the mode, and the large initial velocity corresponds to a wider mode structure, which is different from the instability driven by the trapped particles.

Research on edge carbon impurity transport with resonant magnetic perturbation in the HL-2A tokamak

HAN Yuan-xiang , DONG Chun-feng , SHI Zhong-bing , FAN Dong-mei , CHEN Wen-jin , ZHANG Kai , ZHENG Dian-lin , SUN Ping

2026, 46(1):  97-102.  DOI: 10.16568/j.0254-6086.202601015

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The time evolution of the emission intensity of carbon impurities is measured by an extreme ultraviolet (EUV) spectrometer in the HL-2A tokamak, and it is found that the intensity of the linear emission CIV(312.4 Å: 1s²2s-1s²3p) of C³⁺ ions obviously decreased (~10%) during the introduction of resonant magnetic perturbation (RMP). To help understand this experimental phenomenon, a simulation study of carbon impurity transport with RMP is conducted using the 3D edge plasma transport code EMC3-EIRENE. The simulation results show that under RMP perturbations of the same intensity as the experiment, the CIV intensity in the line-of sight range of the EUV spectrometer decreases (~28%), and the total impurity radiation power within the calculated region decreases (~38%), with the magnitude of the decrease depending on the intensity of the RMP perturbation.The simulation results are consistent with the experimental ones, and it is preliminarily proved that RMP will have an effect on the transport of edge carbon impurities.

Research on optimization of equilibrium configuration for HL-3 tokamak mega-ampere plasma current operation

ZHONG Yuan-yun, ZHONG Wu-lü, XUE Lei, LI Jia-xian, DU Hai-long

2026, 46(1):  103-110.  DOI: 10.16568/j.0254-6086.202601016

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To explore the double null (DN) divertor configuration and the corresponding plasma current (I_p)operation space for supporting the Mega-ampere plasma current operation in the HL-3 tokamak, the relationship between the safety factor q₉₅ and the equilibrium configuration is determined. Combined with the HL-3 first wall structure and the contours of the upper divertor target plate with three different conceptual designs, the free boundary equilibrium code FEEQS is used to design the DN divertor configuration with variant parameters under Ohmic heating. Considering the engineering requirements, the optimal DN configuration parameters such as plasma current I_p =2.5 MA, the toroidal field B_T=2.5 T, elongation к=1.78, triangularity δ=0.65 (for B_T=3 T, I_pmax=3 MA) are clarified when q₉₅ is not less than 3. For the need of the closed divertor research, the feasible optimization design of the upper single null configuration is further carried out for I_p =2 MA, B_T =2.2 T, к =1.64,δ=0.56. These designs provide references for the upper divertor physical research and the operation of the Mega-ampere plasma current discharge on HL-3 tokamak.

Research on AI damage identification of internal components of EAST device based on improved YOLOv8 network

GUAN Zhong-fang, ZHANG Bin , LIU Jian, QIAN Jin-ping , WANG Wei, CHEN Run-ze, YANG Kang-jia , WANG Zu-hao, LU Wen-yi, GUO Yu-tong, HE Chun-yu

2026, 46(1):  111-118.  DOI: 10.16568/j.0254-6086.202601017

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To address the identification of internal component damage to the first wall during the EAST discharge process, the YOLOv8 model is introduced for hotspot recognition, presenting an improved EAST-YOLOv8 algorithm based on the traditional YOLOv8 method. This method can effectively assist manual detection and improve the efficiency of damage detection of internal components in EAST discharge. YOLOv8 behaves poorer in early warning of internal component damage during EAST discharges. According to engineering and physical characteristics of this problem, targeted improvements have been made to YOLOv8,including adding a small object detection layer and incorporating the Convolutional Block Attention Module(CBAM). Then a network suitable for detecting internal component damage under the conditions of long-pulse,high-parameter discharges in EAST has been constructed. Experimental results demonstrate the significant advantages of EAST-YOLOv8 over the original YOLOv8 in terms of loss function and recall rates.EAST-YOLOv8 achieves a detection accuracy of 93.6%, mAP@0.5 of 93.5%, and a recall rate of 93.9%, which offers more efficient and reliable support for the safety and stability of EAST operation.

Distribution and evolution of cesium deposition in a radio-frequency driven negative hydrogen ion source

XIE Wei-min, ZHANG Yu-xian, HUANG Li-ping, ZHANG Xian-ming, WANG Lei, ZHANG Song, ZOU Gui-qing, GENG Shao-fei, LEI Guang-jiu

2026, 46(1):  119-124.  DOI: 10.16568/j.0254-6086.202601018

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Seeding cesium is an important means to increase beam current for a negative ion source on neutral beam systems. In order to investigate deposition distribution of cesium in an RF-driven negative ion source, experiments applied quartz crystal microbalances as sensors have been conducted. The experiments had four phases: (1) cleaning of impurities; (2) static cesium seeding; (3) cesium seeding with heating of the negative ion source; (4) cesium seeding with plasma and heating of the negative ion source. The experimental results indicate that the deposition of impurities keeps stable after long-term cleaning by plasma and has no influence on the cesium seeding experiment. Amount of cesium deposits into the gap between the flange of the diffusion chamber and that of the extraction system. Seeding cesium with plasma and heating of the diffusion chamber can increase cesium deposition to the plasma grid significantly. For long-pulse operation of an RF-driven negative ion source, heating of the flange of the diffusion chamber is also necessary.