Table of Content

15 March 2023, Volume 43 Issue 1

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Nuclear Fusion Engineering

Development of the titanium ion pump current monitor for the LHCD system on HL-2M tokamak

LU Bo, WANG Jie-qiong, CHEN Ya-li, BAI Xing-yu, ZENG Hao, LIANG Jun, WANG Chao, FENG Kun

2023, 43(1):  1-5.  DOI: 10.16568/j.0254-6086.202301001

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The Arduino nano open-source board, SS1306 OLED displayer and SD card are used to develop a titanium ion pump current monitor, which realizes the low-speed acquisition, storage and trend chart drawing for the titanium ion pump current. Both the internal interrupt and the external interrupt are enabled to increase the sample frequency to 1kHz. The experiment result shows that the monitor draws the trend graph correctly and the maximum acquisition error is 0.25μA. 

3D collaborative design for ITER project 

JIANG Tao , WANG Quan-ming , HE Kai-hui , WU Shu-qin

2023, 43(1):  6-11.  DOI: 10.16568/j.0254-6086.202301002

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The 3D collaborative design platform for ITER project was presented, including the basic types of 3D models, expression methods, data exchange methods, personnel training and qualification examination, etc. Taking ITER gas injection system procurement arrangement as an example, this paper introduces the application of collaborative design for ITER project engineering design at SWIP. 

Fault analysis and simulation of the short circuit in high-power fusion magnet power supply 

WANG Zhen, HE Shi-ying , HUANG Lian-sheng, CHEN Xiao-jiao , CHEN Tao , WANG Zhen-shang

2023, 43(1):  12-17.  DOI: 10.16568/j.0254-6086.202301003

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The high-power fusion magnet power supply adopts a three-level neutral point clamped (NPC) voltage source converter (VSC) topology. In the case of the short circuit in converter, the charging and discharging of the DC side capacitor causes the fault transient process more complex, which brings challenges to the fault analysis in converter. To solve this problem, based on the background of 3kV and 6kA three-level IGCT high-power VSC, the fault process is studied by establishing the transient equivalent mathematical model of the short circuit in converter. The whole fault process is divided into two stages, namely the discharge of the capacitor on the DC side and the conduction of the diode. The variation trend of voltage and current under fault transient state is analyzed in detail, which lays the foundation for the design of the later protection scheme. Matlab simulation results show the reliability of the analysis method. 

Design and test of high-level collaborative control system for fusion reactor remote handling 

YAO Hai-feng , ZHANG Qiong , YANG Yang , CHANG Sai-sai , PENG Cheng , ZHANG Xuan-chen, CHENG Yong

2023, 43(1):  18-25.  DOI: 10.16568/j.0254-6086.202301004

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A new high-level collaborative control system for remote handling of fusion reactors based on the robot operating system (ROS) was proposed to tackle the problems of overly integrated function modules, poor extendibility, and absence of mid-level motion planning ability of the original system. The system adopted distributed architecture, based on a mature development platform, and integrated middle-level motion planning and dynamic virtual simulation functions. The “shaft pin grasping” experiment demonstrated that the high-level control system satisfied the design requirements and stability. 

Analysis of current sharing of the converter for toroidal field magnet power supply 

YANG Ya-long, ZHANG Ling, JIANG Li , WANG Chong-ma

2023, 43(1):  26-32.  DOI: 10.16568/j.0254-6086.202301005

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In the analysis of current sharing characteristics of toroidal field magnet power converter, the equivalent circuit model of the high-power converter bridge arm is established by segmenting the bridge arm and extracting the distribution parameter matrix of branches, and the current sharing coefficients of each branch are calculated. The bridge arm current of the converter is obtained by simulation. The simulation results are basically consistent with the analysis, and the current sharing coefficients are all less than the design value of 1.20. 

Study on braking system of double Y shift 30° pulse generator 

WANG Hai-bing, XUAN Wei-min, PENG Jian-fei, LI Hua-jun

2023, 43(1):  33-37.  DOI: 10.16568/j.0254-6086.202301006

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By calculating for the cases of 300MVA pulse generator using the different braking resistance, capacity to cool the brake resistance was determined. By analyzing, it is obtained that the smaller the external series resistance, the braking time is shorter. In the case of small resistance, the stator and rotor heat of generator is better. In the case of 0.15Ω resistance braking, the actual braking waveform and calculated one of the 300MVA pulse generator are basically consistent, and the electrical braking calculation proposed in this paper can be used in the design of electrical braking design.

Structural stability analysis of CFETR vacuum vessel based on finite element method 

GONG Zheng, HAN Song-bo , NI Xiao-jun , GE Jian , HUANG Jian-jun , YU Bin, GAO Xiang, SUN Jin-xing

2023, 43(1):  38-42.  DOI: 10.16568/j.0254-6086.202301007

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真空室是中国聚变工程实验堆(CFETR)重要的屏蔽组件和包容屏障，为提高其结构稳定性，用有限 元方法对真空室核心部件进行了线性屈曲分析与几何初始缺陷非线性屈曲分析，评估了真空室结构的各项稳定性 指标。结果表明，现有的真空室的设计满足屈服强度的设计要求，为后续的设计优化工作提供了重要的理论依据和参考。 

Main loop and compensation network design of fast voltage regulation PSM power supply

LU Wei, , HUANG Yi-yun , PAN Sheng-min

2023, 43(1):  43-49.  DOI: 10.16568/j.0254-6086.202301008

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Due to the lacking adjustability and the low accuracy of the DC output voltage of a single power supply module (PSM) power module in the NBI system, a method of connecting a voltage regulation power supply in series with the output side of the PSM power module is proposed. In order to make the voltage regulation power supply have good dynamic performance, a compensation network is designed. Finally, a prototype is built, and the experimental results verify the correctness of the main circuit design. 

Design and analysis of filament power supply for high-current ion source

PAN Jun-jun, LIU Zhi-min, JIANG Cai-chao, LIU Sheng, CHEN Shi-yong, HU Chun-dong

2023, 43(1):  50-54.  DOI: 10.16568/j.0254-6086.202301009

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The filament power supply is an important part of the plasma generator power supply system of the neutral beam injector. In order to meet the requirements of its low voltage and high current output characteristics, a dual inverse star rectifier circuit with balanced reactor is proposed to design the power supply. Compared with three-phase bridge rectifier circuit, this topology can achieve higher power, less harmonics of input current and improve power factor. The output characteristics and harmonic components of the rectifier are analyzed. The parameters of rectifier transformer and balanced reactor are calculated according to the design index. Finally, the advantages of this topology are verified by simulation and experimental results. 

Preliminary RAMI analysis of CFETR 25kW 4.5K helium refrigerator 

ZHONG Yun-ke, CHEN Xin, ZHU Gen-liang, YANG En-peng, FU You-kun, CAI Li-jun, LI Qiang

2023, 43(1):  55-61.  DOI: 10.16568/j.0254-6086.202301010

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The RAMI analysis was carried out to evaluate the 25kW/4.5K helium refrigerator. The reliability and availability of the system were calculated by the reliability block diagrams. The FMECA analysis was indicated the failure modes of helium refrigerator and proposed the mitigation and maintenance measures. 

Design of constant temperature water supply system for CFETR N-NBI verification prototype 

YI Wei , HU Chun-dong, , XIE Yuan-lai, , XIE Ya-hong, , LIU Wei , WEI Jiang-long , GU Yu-ming , LIANG Li-zhen, , TAO Ling , CUI Qing-long , ZHAO Yuan-zhe , JIANG Cai-chao , XU Yong-jian,

2023, 43(1):  62-67.  DOI: 10.16568/j.0254-6086.202301011

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 By analyzing the working conditions of plasma grid of the negative ion source based neutral beam injection system (N-NBI) verification prototype for China Fusion Engineering Test Reactor (CFETR), the technical parameters of the water supply system with constant temperature are determined, and the constant temperature water supply system of CFETR N-NBI verification prototype is designed. 

Optimal design of the microwave exciter for LHCD system

ZENG Hao , FENG Kun , LIU Li-juan , BAI Xin-yu , WANG Chao , CHENG Ya-li , LIANG Jun , LU Bo

2023, 43(1):  68-74.  DOI: 10.16568/j.0254-6086.202301012

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The problem that the response frequency of the klystron will be shifted after long-term operation
and the analog phase-locked loop cannot work at the optimal frequency of the system has been solved by using of
digital phase-locked loop technology to achieve high-precision and adjustable frequency output performance
within a certain bandwidth. A power amplitude control circuit is added after the shifter to ensure that the output
power of the linear amplifier will not be affected by the phase adjustment. A waveform control unit based on the
combination of digital-to-analog conversion (D/A) technology and microwave electrically adjustable technology
is designed to solve the problem that the output waveform of the exciter is uncontrollable. Through the above
three improvements, the performance optimization design of the microwave exciter of the LHCD system on
HL-2M tokamak has been completed. 


Design and simulation of the stripping unit and the analysis unit of a parallel electric and magnetic field NPA

QU Yu-fan , ZANG Lin-ge , LIN Wei-ping , LUO Yuan

2023, 43(1):  75-81.  DOI: 10.16568/j.0254-6086.202301013

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The neutral particle analyzer with parallel electric and magnetic field (E//B NPA) is introduced, which is capable of both mass and energy resolution. The development of the NPA mainly includes the structural designs of the stripping unit and the analysis unit. The stripping unit is composed of a stripping room (equipped with two differential tubes and a gas supply bellows), a vacuum chamber (with a neutral particle entrance hole and an ion exit hole) and a vacuum pumping system. The stripping efficiency is calculated in the form of global efficiency R×f₊₁, where R is the transmission rate and f₊₁ is the fraction of plus one charge state. The analytical magnetic field of the E//B NPA is produced with the magnet composed of the permanent magnet, pole and yoke. The yoke and the poles are made of mild steel and the permanent magnet is made of NdFeB. The magnetic poles are specially designed to focus the ion trajectories and to increase the usage of the magnetic field. In the charged particle trajectory simulation, the H⁺ and D⁺ ion hitting points distribute in two straight lines at the detector plane. The energy of the ions increases as the hitting position changes from left to right. The energy ranges in the simulation are 20~200keV for H+ and 10~200keV for D⁺ , respectively. This satisfies the diagnostic demand for the mass spectrum and energy spectrum of fast ions in neutral beam injection heating plasmas on HL-2A and HL-2M tokamaks. 

Estimation of the equivalent leak rate for the tritium contained pipes of ITER gas injection system

HUANG Xiang-mei, LI Wei, JIANG Tao, LI Bo, XIA Zhi-wei

2023, 43(1):  82-87.  DOI: 10.16568/j.0254-6086.202301014

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The leak of tritium will cause radiation hazard for public safety and environment, therefore the leak of tritium contained pipes should be analyzed. The tritium contained pipes of the ITER gas injection system are analyzed in this paper. An estimation on the air equivalent leak rate at the tritium alarm threshold (3×10⁵ B_q·m^-3 for environment, 1×108 Bq·m‒3 for pipes) is given for the leak of the tritium supply pipe, the neutralizer pipe and the ion source pipe. The results show that the leak of the tritium supply pipe has highest risk. Although the tritium supply pipe operates at a pressure lower than that in the surrounding enclosure, leak rate higher than 3.2×10^-8 Pa·m³ ·s^-1 will trigger the tritium alarm due to high tritium concentration. To the contrary, the ion source pipe operates at a much higher pressure than that in the surrounding enclosure but has low tritium concentration. It will trigger the tritium alarm at leak rate higher than 6.1×10^-6 Pa·m³ ·s^-1 . The leak hazard of tritium contained pipes of gas injection system is not negligible, and real time monitoring and protecting is necessary. 

Study on the transformation of laser welding mode of reduced activation ferritic/martensitic steel CLF-1 

GOU Jun, WANG Ping-huai, ZHU Xiao-bo, WANG Chang-hao, HU Dan, QIU Rong, LIAO Hong-bin, CHEN Ji-ming

2023, 43(1):  88-93.  DOI: 10.16568/j.0254-6086.202301015

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In order to study the laser welding mode transformation law of the reduced activation ferritic/martensitic steel (RAFM) CLF-1, the cross-section of the weld was macroscopically characterized and the weld size of was quantitatively analyzed. The results show that, under certain conditions, with the increase of the laser welding power, the welding mode changes from the heat-conduction welding mode to the deep-penetration welding mode, and there are three types of weld morphologies, ‘circular arc-shaped’, ‘V-shaped’ and ‘nail head-shaped’. The laser welding mode of CLF-1 steel is not affected by the welding speed and defocus. The critical value of the welding mode transition is the deep-penetration welding threshold, which is determined by the characteristics of the CLF-1 steel itself. The deep-penetration welding threshold of CLF-1 steel is about 1.20kW^.mm⁻¹ when the laser welding speed is 10mm^.s ⁻¹ . 

Transverse compressive properties of stacked REBCO superconducting strands 

SUN Lin-yu, ZUO Jia-xin, LAI Xiao-qiang, LI Peng-yuan

2023, 43(1):  94-98.  DOI: 10.16568/j.0254-6086.202301016

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In this paper, a variety of stacked strands of 2mm wide REBCO superconducting tapes were prepared by stacking, rounding and drawing techniques, and the transverse compressive properties of various specifications of the strands were researched by experimental methods. The results show that the distribution of REBCO tapes and copper strips has almost no effect on the compressive property, and increasing the wall thickness of the jacket can improve the compressive performance, while increasing the diameter of the strands can improve the compressive capacity, but the twisting of the strands will reduce its compressive performance. 

Study on the frictional wear performance of MoS2 coatings under different load and speed conditions 

DONG Si-cheng, ZHONG Li, DAN Min, XU Ze-jin, WANG Xin-chao, ZHOU Yi, JIN Fan-ya

2023, 43(1):  99-104.  DOI: 10.16568/j.0254-6086.202301017

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In order to study the friction and wear characteristics of molybdenum disulfide (MoS₂) coatings on the surface of fusion reactor components, the (002) oriented MoS₂ coating was prepared on A286 substrate with thickness about 2μm by unipolar pulsed magnetron sputtering. The tribological properties of MoS₂ coating under different rotating speeds and loads in atmospheric environment were investigated by pin-on-disc tribo-tester. The research results show that the friction coefficient of the coating decreased with the increase of the test speed when fixed test load of 13N, and the relatively small average friction coefficient of 0.0722 was obtained at the rotation speed of 50rpm in the whole process. When fixed the rotation speed at 20rpm, the friction coefficient decreased firstly and then increased with the increase of test load. Detailed for the test load of 7N, the average friction coefficient of 0.0763 was obtained in whole test process. 

Plasma Physics

Application of high energetic particle redistribution model in CFETR

HAO Bao-long , CHEN Wei , LI Guo-qiang , WANG Xiao-jing , WU Bin , GAO Xiang , CFETR TEAM

2023, 43(1):  105-111.  DOI: 10.16568/j.0254-6086.202301018

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The work investigated the MHD induced energetic particle loss and redistribution based on CFETR physics parameters and NTM numerical simulation results. The new method of phase vector rotation is to determine the KAM surfaces broken or not with following the test orbit pairs and recording the joint vector rotation in each small domains of phase space, which indicates the orbit stochasticity. The particle redistribution and loss can be derived with the stochastic template. The work demonstrated the distribution of energetic alpha particles and obtained the stable particle profile with the method of phase vector rotation. The work did not find resonant island within trapped particle region, the MHD perturbation and finite collisions can induce a loss channel near the trapped-passing boundary region of phase space. 

Experimental study of fluorescence frequency limit in LIF diagnosis 

LUAN Chun-yang, , XU Guo-sheng , Yip Chi-Shung , JIANG Di , ZHANG Wei , JIN Chen-yao

2023, 43(1):  112-116.  DOI: 10.16568/j.0254-6086.202301019

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In Laser-Induced Fluorescence (LIF) diagnosis of argon plasma, the relationship between laser frequency and signal intensity was studied. Under the given plasma discharge parameters, there is a limit frequency of incident laser, above which the fluorescence intensity will not increase. The limit frequency varies with the size of hole in the lens group in the fluorescence collection system. 

Study on the characteristics of helicon plasma excited by high pass birdcage coil 

TANG Dong , FU Wei , CHEN Jian-jun , WANG Hong-bin , GOU Fu-jun, SUN Shou-hua, YE Zong-biao , ZHANG Kun

2023, 43(1):  117-124.  DOI: 10.16568/j.0254-6086.202301020

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A high-pass birdcage coil is developed as plasma source, and argon gas is used as working gas to preliminarily evaluate the performance of RF antenna. COMSOL5.4 is used to simulate the linear polarization distribution of the electric and magnetic fields of the cage antenna at 13.56MHz. The circuit structure of birdcage coil is dissected and the formula for calculating its resonant frequency is deduced. The outer temperature of the cage coil is significantly lower than that of the traditional RF antenna under normal working conditions, and the maximum temperature of the capacitor is only 65.8°. The spectral characteristics of helicon wave plasma discharge were diagnosed by spectrograph. The density of helicon wave plasma was diagnosed by Langmuir probe under different pressure and magnetic field intensity. The plasma density reached 1.62×10¹⁸m⁻³ at 1.0Pa, 600Gs and 700W RF power. The plasma density corresponding to forward and reverse power is diagnosed and the variation trend is similar to that of hysteresis. The radial density distribution of helicon wave plasma is measured, and its density reaches the highest at the axis. The characteristics of plasma in the absence of magnetic field were also investigated. The density value of plasma did not have a large transition. The longitudinal magnetic field was the key factor to trigger the helicon wave plasma discharge. The results show that birdcage coil has obvious advantages in the excitation of large volume and higher density helicon wave plasma due to its low heat consumption and high feed, which can be used in the next stage of hydrogen helicon wave plasma excitation.