Nuclear Fusion and Plasma Physics

Simulation and analysis of the effect of pumping on carbon impurity distribution in HL-2M conventional divertor

ZHOU Yue, ZHENG Guo-yao, DU Hai-long, PAN Yu-dong, LI Jia-xian, XUE Lei, PAN Wei，HUANG Wen-yu, XUE Miao, PENG Yuan-yuan, QU Cheng-hai

2021, 41(2): 97-104. DOI: 10.16568/j.0254-6086.202102001

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在小角度V型结构的HL-2M常规偏滤器位形下，采用SOLPS 5.0程序研究了抽气速率S_p对装置粒子排除控制能力及溅射产生的碳杂质分布的影响。模拟结果表明，当进入边缘区域的能量为4MW、上游密度为n_sep=3.0×10¹⁹时，过高的抽气速率(大于40m³•s^-1)将迅速降低靶板附近中性粒子压强和等离子体密度，并引起靶板电子温度T_e的上升和表面材料溅射增强，导致有效电荷量Z_eff升高。在抽气速率约为20~40m³×s^-1时，常规偏滤器的粒子排除效率较高。

Simulation of lower hybrid current driving in high field side on tokamak

LIN Jia-fan1, ZHENG Ping-wei2, 3, GONG Xue-yu1, DENG Sheng1, JIANG Xin-chen2

2021, 41(2): 105-109. DOI: 10.16568/j.0254-6086.202102002

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Lower hybrid current drive (LHCD) on an EAST tokamak double null configuration was studied with the GENRAY/CQL3D code. The simulation results show that the high filed side (HFS) LHCD efficiency is lower than that at the low filed side (LFS) for low electron density discharges. As the electron density increasing, the advantages of HFS LHCD gradually emerge. Lower hybrid wave (LHW) launched from the HFS deposits its energy closer to the plasma center. Increasing toroidal magnetic field intensity can help the propagation of LHW. Increasing plasma pressure of magnetic equilibrium configuration in the same proportion with the electron density, the effect of HFS lower hybrid current drive is better than that of LFS LHCD.

Preliminary experiment of fast vacuum ultraviolet spectroscopic diagnostic system on EAST

HE Liang, ZHANG Hong-ming, CAO Jin-jia, SHEN Yong-cai, LI Ying-ying, FU Jia, ZHANG Ling, DAI Shu-yu, WANG Fu-di, HU Rui-ji, LIU Bing, ZHANG Xiao-long, XU Zong, BIN Bin, YANG Jin, Gong Xue-yu

2021, 41(2): 110-117. DOI: 10.16568/j.0254-6086.202102003

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A vacuum ultraviolet (VUV) spectroscopic diagnostic system has been developed on EAST to measure the edge impurity radiation in high-parameter discharges. One Seya-Namioka spectrometer with focus length of 200mm is used for the spectroscopy. The spectrometer is equipped with a holographic concave grating with groove density of 600g•mm^-1. The observed wave length range is from 50nm to 700nm, covering the VUV, near ultraviolet and visible ranges. The minimum sampling time can be set as 5ms. The observed vertical range is from Z=-350mm to 350mm. The present spectroscopy has been used to measure the spectra from edge impurity of EAST plasma. Time evolution of CⅣ(154.8nm) and FeⅡ(235nm)have been analyzed to verify the system capability. The time evolution of CⅠ(365.2nm) has also been studied for modulated NBI discharge to verify system ability to study impurity behaviors in relatively short time scale.

Neutronics effect analysis of homogeneous model on CFETR helium cooled ceramic breeder blanket

QU Shen, CAO Qi-xiang, DUAN Xu-ru, WANG Xue-ren, WANG Xiao-yu

2021, 41(2): 118-123. DOI: 10.16568/j.0254-6086.202102004

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Neutronics calculations based on homogeneous and high-fidelity models for CFETR helium-cooled ceramic breeder (HCCB) blanket have been performed, and results are summarized in this paper, including tritium breeding rate (TBR), neutron spectrum, power distribution and etc. The neutronics effect of homogeneous structure and space self-shielding effect on CFETR HCCB are performed. Also, neutronics effect on the size of the pebbles to the TBR is studied. Results show that the homogeneous model has small impacts on the neutronics performance of CFETR HCCB blanket, the space self-shielding effect of the pebble beds shows a descending trend when the diameter of pebbles decreases and the space self-shielding effect caused by pebble beds has little effect on the neutronics performance of CFETR HCCB blanket. Finally, the results verify that the homogeneous model for neutronic analyses of the HCCB blanket are rational, and the design basis for the high-fidelity neutronic calculation has been provided.

Analysis on microstructure and properties of W/Fe/CuCrZr module bonded by HIP technique

WANG Yi-ming, HUANG Pan, CHEN Ji-ming, WANG Ping-huai

2021, 41(2): 124-130. DOI: 10.16568/j.0254-6086.202102005

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In order to achieve reliable connection of plasma-facing material tungsten and heat sink material CuCrZr alloy, the feasibility of using pure iron as the interlayer of W and CuCrZr alloy bonded by hot isostatic pressing (HIP) techinique was explored. An experimental module of W/Fe/CuCrZr alloy was fabricated under the hot isostatic pressure of 850℃/150MPa/135min, and the welding interface, the micro-morphology, the microstructure composition and the shear mechanical properties of the connection interface were measured and analyzed. The results show that there are no obvious defects on the two connection interfaces, and short-distance interdiffusion of about 0.5μm has occurred, and no obvious reaction phase has been formed. The connection interface shows good plasticity and the shear strength is greater than 186.5MPa. Thereby, pure Fe as an intermediate layer achieves a reliable connection of W/CuCrZr alloy. The module’s transient heat transfer under high heat flux simulated with ANSYS Workbench shows that the W/Fe/CuCrZr alloy module can withstand a maximum heat flux of 16MW·m^-2.

Study on the effective thermal conductivity of different packing schemes of tritium breeder pebble beds

WANG Cong1, 2，CHEN Lei1，LIU Song-lin1

2021, 41(2): 131-137. DOI: 10.16568/j.0254-6086.202102006

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A heat transfer analysis model of pebble beds is established based on discrete element method and computational fluid dynamics coupling method (DEM-CFD). The validation of DEM model, grid sensitivity analysis and heat transfer model are carried out. Based on the above model, the effective thermal conductivity of Li₂TiO₃ pebble beds with particle size distribution, unitary Li₂TiO₃ pebble beds and binary Li₂TiO₃ pebble beds is further simulated and calculated. The influence of particle size distribution, different particle sizes and mixing on the effective thermal conductivity of Li₂TiO₃ pebble beds is studied. The results show that for the Li₂TiO₃ pebble beds with similar packing factor, the effective thermal conductivity of Li₂TiO₃ pebble beds with particle size distribution is similar with unitary Li₂TiO₃ pebble beds with equivalent particle size. In the case of negligible radiation heat transfer, the effect of particle size on the effective thermal conductivity of unitary pebble bed is negligible. Compared with unitary Li₂TiO₃ pebble bed, the binary Li₂TiO₃ pebble bed has higher packing factor and effective thermal conductivity.

Simulation design and analysis of traveling wave antenna of CFETR helicon wave

YANG Yu-qing1, QIN Cheng-ming2, ZHAO Yan-ping2, YANG Hua2

2021, 41(2): 138-142. DOI: 10.16568/j.0254-6086.202102007

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A travelling wave antenna (TWA) has been proposed for helicon wave current drive under China fusion engineering test reactor (CFETR) physical design parameters. Using the commercial software package CST, the antenna model is simulated. The results show that the voltage standing wave ratio (VSWR) of antenna is less than 1.2 in 50MHz bandwidth and the k-spectrum excited by antenna array is well localized, which is in favor of enhancing the efficiency of current driving.

Preliminary design of primary heat transfer system for CFETR water-cooled breeder blanket and simulation of balance of plant

WANG Kai-song1, SUN Ming-ming1, XU Kun2

2021, 41(2): 143-149. DOI: 10.16568/j.0254-6086.202102008

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Two sets of independent primary heat transfer system (PHTS) were designed to provide cooling for breeding zone (BZ) and first wall (FW) on China fusion engineering test reactor (CFETR), respectively. An intermediate heat transfer system (IHTS) was designed between FW PHTS and power conversion system (PCS), and the influence of pulse operation on PCS was solved. A set of balance of plant (BOP) system model with Ebsilon software is built to simulate the operation condition of the system under 1.5GW fusion power. The preliminary design gives the design and layout of PHTS, including pipes, steam generators, intermediate heat exchangers and pumps. According to the simulation results, the system can operate stably at 80% power at the pulse/dwell time of 2h/0.5h, ensuring PCS to have continuous and stable power output.

Analysis on network topology delay of ITER PF power supply field layer monitoring system

YANG Ya-long1, 2, 3, XU Qiang-lin1, 3, LIU Wei1, 3, GAO Ge2

2021, 41(2): 150-156. DOI: 10.16568/j.0254-6086.202102009

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In order to guarantee the high real-time control requirement of ITER poloidal field (PF) power supply system, according to the characteristics of ITER poloidal field power supply device, such as large size and decentralized distribution, a real-time industrial Ethernet field bus EtherCAT supporting multiple device connection topologies is selected as the data communication protocol of ITER PF power supply field layer monitoring system. In addition, in order to study the real-time performance of ITER poloidal field power supply field layer monitoring system, the transmission delay of data frames in several field bus device network topologies suitable for ITER PF rectifier unit field layer signal acquisition and control is analyzed, and the feasibility and correctness of the scheme design are verified by building a test platform. While satisfying the high real-time requirement of the control system, a suitable device network topology is found out through comparison for the design of the ITER PF power supply field layer monitoring system, which also provides a reference for the topology optimization of other sub-control systems of ITER PF power supply.

Study on thermal performance of Be/Cu joint of ITER first wall components under high heat flux

ZHAO Bao-ling 1, CHEN Ji-ming 2, WU Jing2, KANG Wei-shan2

2021, 41(2): 157-161. DOI: 10.16568/j.0254-6086.202102010

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The thermal performance of Be/Cu joint of ITER first wall components was studied under the high heat flux. The thermal stress and thermal strain of Be/Cu joint are simulated, and the corresponding thermal fatigue life is obtained. The results indicate that the thermal and thermal fatigue performances of the current design of Be/Cu joint under 4.7MW×m^-2 high heat flux and ITER normal operation condition can meet the design requirements.

Study on the inspection of welding deformation in the development of ITER ELM coils

ZHENG Yuan-yang, GU Yong-qi, YUAN Zhong, LIU Chen, WANG Jun, JIN Jing, HAN Hou-xiang

2021, 41(2): 162-166. DOI: 10.16568/j.0254-6086.202102011

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A method of measuring the welding deformation of coil based on laser scanning and reverse modeling is proposed to measure the welding deformation of ITER ELM coil. The results show that the accuracy is better than 0.1mm, satisfying quantitative detection of welding deformation. During the improvement and evaluation of ITER ELM coil welding process, the measurement of deformation of coil and tooling during welding completed with this method provides reliable quantitative data for welding process evaluation.

Simulation analysis of enhanced heat transfer of tube with twisted tape inserts under non-uniform heating

LIU Ping, DING Wen-long, JIN Hai-bo

2021, 41(2): 167-173. DOI: 10.16568/j.0254-6086.202102012

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When water is set as the working medium, the Euler multiphase flow model and non-equilibrium boiling model are adopted, the flow velocity is in the range of 0.3~0.7m·s^-1, the working pressure is 4.5MPa, and the heat flux density is 2MW·m^-2, the subcooled boiling heat transfer in the tube with twisted tape inserts and plain tube has been simulated numerically. The heat transfer coefficient, void fraction, flow velocity, flow field streamline, solid component temperature and pressure drop of two kinds of tubes were compared, and the comprehensive performance of the tube with twisted tape inserts has been analyzed. The results show that the heat transfer coefficient of the tube with twisted tape inserts increases by 6% to 90% or so, and the pressure drop increases by about 200% to 250%, compared with the plain tube. When the flow velocity is in the range of 0.4~0.6m·s^-1, the comprehensive performance evaluation factor η of the tube with twisted tape insert is 1.1~1.3.

Phase lock method on the wide frequency of the pulse power supply system

WANG Hai-bing, XUAN Wei-ming, WANG Ying-qiao, LI Hua-jun, LIU Xiao-long

2021, 41(2): 174-177. DOI: 10.16568/j.0254-6086.202102013

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In order to solve the problem that the traditional phase-locked loop cannot perform correct phase-locking under the condition of the fundamental frequency is variable, a tracking three-phase software phase-locked loop based on the synchronous reference coordinate system is proposed. The three-phase voltage signal (V_a, V_b, V_c) is transformed by the synchronous coordinate to obtain the two-phase stationary coordinate signal (V_α, V_β), and then the signal (V_d, V_q) is obtained after the rotating coordinate. Then the Vq signal is low-pass filtered and through dynamic signal delay. The delay time is obtained from the output frequency signal. The signals difference of before and after the delay are adjusted by PID and output as the angular frequency. After the angular frequency is integrated, the stable fundamental positive sequence phase is obtained. In order to verify the algorithm, a simulation model is established based on matlab. The simulation results showed that the phase shift time of the PLL was less than 0.2ms in the case of the linear change of the fundamental wave frequency of the power supply, and In the case of non-linear changes in the fundamental frequency of the pulse generator voltage, it takes one cycle to obtain accurate phase lock. Its application in active power filters effectively suppresses the output harmonics of pulse generators.

Investigation of magnetic field distribution in ferritic steel rectangular duct under external strong magnetic fields

ZHAO Yao, ZHANG Xiu-jie, PAN Chuan-jie, XU Zeng-yu, WANG Lei, WANG Fan

2021, 41(2): 178-182. DOI: 10.16568/j.0254-6086.202102014

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The magnetic induction intensity distribution at the center of a ferrite rectangular duct under the external strong magnetic field environment is simulated with Ansys magnetostatic module. Compared with the literature results, analytical solutions and experimental data, simulation results are basically consistent with them. Further numerical simulations also show that the ferrite rectangular duct has a great influence on the overall magnetic field distribution inside it, and it induced magnetic field line distortion and non-uniform magnetic induction intensity distribution are different in different regions. This distribution may have a greater impact on the magnetohydrodynamic effects in the duct.

Effect of gas flow rate on back-streaming electron in the high current positive ion source for neutral beam injection

WU Ming-shan1, 2, HU Chun-dong1, 2, XIE Ya-hong1, 2, YI Wei1, XU Yong-jian1, LIANG Li-Zhen1, 2

2021, 41(2): 183-186. DOI: 10.16568/j.0254-6086.202102015

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The generation and behavior of the back-streaming electrons during the beam extraction process for EAST-NBI ion source are analyzed, and the influence of gas flow rate on ion source is calculated, and experimental research is carried out in typical cases. The experimental results indicate that gas flow rate has little effect on the proton ratio, and there is a positive correlation between gas flow rate and the flux of back-streaming electron.

The characteristics of electron extraction of inductively coupled plasma neutralization gun

LUO Xian-wen

2021, 41(2): 187-192. DOI: 10.16568/j.0254-6086.202102016

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A design of inductively coupled plasma source using in plasma neutralization gun is present. The electron extraction characteristics of the plasma source were studied experimentally, and the relationship between plasma density and RF power was analyzed. The results show that the electron extraction characteristics of the plasma source are related to the gas pressure in the discharge chamber, and the change of electron density during E-H mode conversion is related to the inductance of the load.

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