Nuclear Fusion and Plasma Physics

Modeling study on the effects of drifts on tungsten impurity production and transport in EAST

LIU Hong-tao, WANG Fu-qiong, ZHONG Fang-chuan

2019, 39(4): 289-295. DOI: 10.16568/j.0254-6086.201904001

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In this paper, the Monte-Carlo impurity transport code DIVIMP is used to simulate the tungsten impurity production and transport properties under different drift conditions (no drifts, ion B× B drift directing to the upwards/downwards) for the discharge of the upper single null in the experimental advanced superconducting tokamak (EAST) device. The results show that the classical drifts significantly affect the tungsten impurity sputtering from the divertor target and its content in the upstream.

Development of the digital high-precision thermocouple instrument for the LHCD system on HL-2M tokamak

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

2019, 39(4): 296-300. DOI: 10.16568/j.0254-6086.201904002

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A 16-channel J-type thermocouple instrument with digital calibration for the lower hybrid current drive (LHCD) system on HL-2M tokamak was developed to achieve 16 channel temperature measurements. The temperature measurement range is 0~250°C with the absolute error value less than 1°C. The temperature can be displayed on the liquid crystal display (LCD) and read on the computer remotely. The J-type thermocouple instrument has been successfully used in the debugging experiment of the LHCD heating system of HL-2M tokamak. The temperature of output cavity of the high power klystron has been measured under different output power conditions to ensure the safety of the klystron in operation.

Tritium transport analysis for water cooled ceramic breeder blanket

ZHANG Bing1, 2, ZHAO Xue-li1, 2, MA Xue-bin3, 4, LIU Song-lin1

2019, 39(4): 301-308. DOI: 10.16568/j.0254?6086.201904003

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Based on the design of the 2015 version of China Fusion Engineering Test Reactor (CFETR) water cooled ceramic breeder (WCCB) blanket modules surrounding the plasma, a tritium transport model has been developed. Tritium transport analysis has been carried out for each blanket module with different breeding zones, purge gas loop, coolant loop and steam generator. The results indicate that the concentration, permeability and retention of tritium among blanket modules are different. For all of the WCCB blanket modules in CFETR, the tritium retention inside the breeder is 6.62×10^-2g, the tritium retention inside the structural materials is 2.01g, the tritium retention inside purge gas and coolant loop are 4.03×10^-4g and 0.19g respectively, the tritium permeation through the steam generator tube walls is 20mg•y^-1, the tritium permeation from the coolant pipes is 0.1mg•y^-1.

Coupled heat transfer characteristics study of multi-flow field between lead lithium and helium gas for liquid blanket breeder zone of fusion reactor

WANG Wei-hua1, 2, CHENG De-sheng2, DENG Hai-fei2,WANG Xiao-yu3, CHU De-lin1, LIU Sheng1

2019, 39(4): 309-316. DOI: 10.16568/j.0254-6086.201904004

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The coupled heat transfer of multi-flow field in liquid blanket breeder zone of fusion reactor has been simulated by three-dimension computational fluid dynamics (CFD) method. The filling-evacuating high-pressure helium-cooled loop and the heat exchange test module have been built, and the contrast experiments of coupled heat transfer of multi-flow field have been implemented for validating numerical calculation results. The flow and heat transfer characteristics, and its effect on the condition of varied helium gas operational pressure and liquid lead lithium inlet temperature, nuclear heat power density in breeder zone were studied. The heat transfer coefficient and correlation formula of helium and RAFM steel surface, liquid lead lithium and RAFM steel surface were presented. The results will be beneficial for the design, research and development of liquid blanket.

Research on flow-induced-vibration of the cooling system in HL-2M divertor

ZHANG Long, LU Yong, CAI Li-jun, LIU Yu-xiang,YUAN Ying-long, LIU Jian, LAI Chun-lin

2019, 39(4): 317-323. DOI: 10.16568/j.0254-6086.201904005

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Based on ANSYS/CFX fluid-solid coupling method, the flow-induced vibrations of the HL-2M divertor cooling system under different flow rates and different metal hoses were evaluated. The results show that the equivalent elastic modulus of the metal hose is the main factor affecting the vibration response of the system. The influence is negligible if the average flow velocity of the fluid is controlled in 2~10m·s^-1. The maximum occurrence probability of the main deformation area appears in the vicinity of U-tube and the metal hose. A metal hose with an equivalent elastic modulus of E≥1010Pa should be chosen, and a strengthened support is suggested to be added nearby the U-tube and the metal-hose to ensure safety.

Thermal fatigue analysis of HL-2M snowflake-minus divertor

SHEN Jun-tian1, 2, YUAN Ying-long1, YAO Lie-ming2, ZHANG Wang1, 2, CHEN Ya-jing1, 2, ZHOU Ming-tao1, 2, WEN Hao1, 2, WU Jing2

2019, 39(4): 324-330.

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The heat flux distribution on the plasma facing surfaces of divertor for HL-2M tokamak has been simulated with the SOLPS code. Temperature and thermal stress have been calculated with finite element method, and the fatigue life of divertor has been evaluated with the structural design criteria for ITER in-vessel components (SDC-IC). The results indicate that most area of the target planes do not experience severe plastic fatigue under the cycles. But, the fatigue life of dome plane, 4mm away from outer pumping port, is approximately 1963 times. This result might be useful for HL-2M tokamak divertor design.

Study on the amorphous brazing technology of CFC/CuCrZr target plat for HL-2M divertor

WANG Jian-bao1, LIAN You-yun1, FENG Fan1, CHEN Zhe1,TAN Yang1, WANG Jin1, LIU Xiang1, WANG Ying-ming2

2019, 39(4): 331-337. DOI: 10.16568/j.0254-6086.201904007

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The brazing process of chlorofluorocarbon/oxygen-free-copper (CFC/OFC) composite mockup and CuCrZr at 710~750°C by vacuum brazing and with STEMET-1101 amorphous filler is studied. Firstly, the microstructure and melt behaviors of the filler are characterized by means of XRD and differential scanning calorimetry and then the organism form, elemental distributions, phase structures, and mechanical property in the bonding seams are studied by using optical microscopy, electron probe microanalysis and tensile tests. The thermal fatigue property of CFC/OFC/CuCrZr brazing mockup is measured with the high heat flux facility. The results show that the bonding seam consists of Ni(Cr, Cu)2P particles, Cu(Ni)3P phase and Cu matrix in brazing temperature of 710~750°C, which is smooth and crack-free. Especially, a continued intermetallic phase network in the bonding seam is depressed in the case of 750°C/15min treatment. The welding strength of the OFC/CuCrZr is higher than tensile strength of OFC. The bonding strength of CuCrZr/CuCrZr joint is 210MPa and fracture is partly ductile. The CFC/Cu/CuCrZr mockup prepared in the case of 750°C/15min treatment can tolerate 7MW·m^-2 high heat flux under 1000 cycles.

Research on laser measurement of machining parts of CFETR 1/32 vacuum vessel

JI Hai-biao1, 2, LIU Zhi-hong1, WU Jie-feng1, 3, MA Jian-guo1,FAN Xiao-song1, GU Yong-qi1

2019, 39(4): 338-342. DOI: 10.16568/j.0254-6086.201904008

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The laser tracker is used to determine the locating data of the 1/32 vacuum vessel during its later machining on the machine tool platform. Firstly, the design coordinate system of the workpiece and the base points of assembly are determined by the laser tracker when the workpiece is clamped to the platform of machining tool. Secondly, an auxiliary standard block with XY, YZ, XZ three orthogonal planes features is machined outside the workpiece to establish the machine coordinate system. Then the workpiece and auxiliary standard block are measured simultaneously with the laser tracker to determine the relative positional relationship between the workpiece and the auxiliary standard block. Finally, the machine tool uses the auxiliary standard block as the locating data to complete the machining of the workpiece. Through this method, the machining work of two 1/32 vacuum vessels have been completed, and the machining accuracy is within the range of tolerance requirements, as illustrates the rationality and practicability of the method.

Preliminary design and thermal analysis of CFETR cryostat thermal shield

WANG Kai-song1, BAI Yu-cheng1, GE Jian2

2019, 39(4): 343-347. DOI: 10.16568/j.0254-6086.201904009

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Cryostat thermal shield (CTS) of China Fusion Engineering Test Reactor (CFETR) is designed with 304LN stainless steel being selected as the CTS material. The CTS is divided into 16 sectors with each sector encompassing 20 sub-sectors, the corresponding cooling tubes are arranged on each sub-sector of the CTS panel sector, and liquid helium is selected as the coolant. The thermal analysis of the designed CTS structure is performed based on FLUENT, and the temperature distribution of the CTS panel and the pressure difference between the inlet and outlet of the cooling pipeline are obtained. The results show that the temperature of the CTS panel and the pressure difference between the inlet and outlet of the cooling tubes are within a reasonable range, which verifies the rationality of the layout of the cooling pipeline, and it provides reference for optimal design of the CTS.

Mechanical performance study of copper tube of ITER in-vessel coil conductor

LIU Xiao-chuan1, 2, LIAO Guo-jun3, ZHU Chao3, WU Yu1,QIN Jing-gang1, ZOU Hong-fei2, LIU Sheng4

2019, 39(4): 348-351. DOI: 10.16568/j.0254-6086.201904010

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Mechanical properties of copper (CW009A) tubes in stainless steel mineral insulated conductor (SSMIC) of ITER in-vessel coils (IVCs) were studied. The experiment is carried out at room temperature and elevated temperature. The results show that the mechanical properties of high-purity copper meet the design requirements, and the tensile strength and yield strength are improved at both normal temperature and high temperature. The results provide reference for the design and performance analysis of ITER IVC conductor.

Preliminary system study on conceptual design of HeCEL-3 helium experimental loop

WANG Xiao-yong, WANG Xiao-yu, YE Xing-fu,ZHAO Zheng-ning, LIU Jie, YAN Yong-jiang

2019, 39(4): 352-358. DOI: 10.16568/j.0254-6086.201904011

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Various operating conditions of the HeCEL-3 helium coolant experimental loop, including steady state and transient state scenarios, have been simulated using large-scale system and safety analysis software APROS. The results not only provide reference values for the equipment parameters and the ranges of the thermal hydraulic parameter, but also give the changes of main parameters during transient operation. These provide a comprehensive reference data for the preliminary design of the loop. Meanwhile, the analysis results also can provide references for the design of cooling system of China fusion engineering test reactor (CFETR) and future nuclear fusion reactor.

Study on the applicability of ultrasonic microscopy test in the welding seam of tritium-breeding blanket

WANG Xue-qin, WANG Xiao-yu, LIAO Hong-bin, WU Xing-hua, QIN Chao

2019, 39(4): 359-364. DOI: 10.16568/j.0254-6086.201904012

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Based on the structure design and characteristics of the sealing welding of tritium-breeding blanket cap runner, the ultrasonic microscopic detection technology is studied. The testing parameters and the applicability of the method are determined. The JSR DPR500 ultrasonic microscopic detection system is selected to study the testing parameters. The characteristics of the probe parameters and the focus of the sound beam in the ultrasonic microscopy detection are analyzed. Different parameters and water layer thicknesses are used to improve the detection sensitivity. The problem that the small defects in the sealing welding of cap runner are difficult to detect is solved.

Progress of dust research in plasma devices

YAO Wei-zhi, WANG Jin-chuan, DENG Li, CHEN Chang-an, GAO Bo

2019, 39(4): 362-372. DOI: 10.16568/j.0254-6086.201904013

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The interactions between charged particles and wall materials produce dusts in plasma devices. Progress of dust research on the main plasma devices are reviewed, the approaches to measure dusts and the results obtained in main plasma devices in the world are presented. The unsolved problems and possible directions for further advancements are commented.

Numerical study of characteristics of atmospheric pressure helium plasma discharge driven by dual frequency power

WANG Yi-nan, MENG Xiao-dong, LI Shuai-xing, JIN Ying,WANG Li, ZHANG Yan-hua, SHI Feng-yan

2019, 39(4): 373-378. DOI: 10.16568/j.0254-6086.201904014

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Based on one dimensional fluid model, the characteristics of helium plasma discharge driven by dual frequency at atmospheric pressure were studied. The results show that the electron density and discharge current increase with power voltage both in single frequency discharge and dual frequency discharge. In comparison with single frequency discharge, the discharge current and electron density in dual frequency discharge are lowered due to the coupling of low frequency source. As the voltage of low frequency source increases, the electron density, ion flux, electron energy dissipation, as well as electron heating decrease, whereas electron temperature and potential increase. As the voltage of high frequency source increases, the ion flux nonlinearly increases at the same voltage of low frequency source.

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