Nuclear Fusion and Plasma Physics

Shielding design of container for radioactive waste of CFETR helium cooling blanket

ZHAO Zi-qiang, LI Zai-xin, CAO Qi-xiang

2022, 42(2): 175-181. DOI: 10.16568/j.0254-6086.202202001

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The shielding design of container of radioactive waste decommissioned from Helium Coolant Ceramic Breeder-Tritium Breeding Blanket (HCCB-TBB) for China Fusion Engineering Testing Reactor (CFETR) is studied. The characteristics of radioactive source term for CFETR HCCB are analyzed, the calculation model of container shielding thickness is focused on, and dose rate of container surface is calculated using MCNP5. It is found that there is an exponential attenuation relationship between the container surface dose rate and the thickness of container. According to the relevant requirements of the current standard of container, two design schemes of container with steel material and steel-lead-steel sandwich material are proposed, respectively.

CFETR feeder conductor design and thermal stability performance evaluation

JIN Huan, WU Yu, SHI Yi, QIN Jing-gang, LIU Chen, DAI Chao, ZHANG Yong-liang, , LIU Hua-jun

2022, 42(2): 182-186. DOI: 10.16568/j.0254-6086.202202002

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The structure of feeder conductor is designed as a cable in conduit conductor (CICC), and the busbar is made up of six petal-like cables twisting in the clockwise direction around a centre copper core while petal-like cable is of the four-staged winding structure of compound lines formed by winding clockwise NbTi superconductor wires and copper wires. Its thermal stability performance is analyzed. Results show that the current sharing temperature is less 6K and hot temperature is less 250K under the maximum current with about 95.6kA, meeting design values.

Evaluation of optical performance of microwave reflection imaging system on EAST tokamak

GAO Fei-xue, LIU Xian-zi, QU Cheng-ming, XU Xin-hang, XIE Jin-lin

2022, 42(2): 187-193. DOI: 10.16568/j.0254-6086.202202003

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The channel distance and the detection spot radius of the EAST 96-channel (polar 12-channel and radial 8-channel array) microwave imaging reflectometer have been tested using a metal reflection plane with a width of 1cm as the artificial reflection surface. The results are consistent with the optical simulation results. Using the azimuthal rotating metal wheel surface as the reflecting surface, the Doppler frequency shift introduced by the rotation of the reflecting surface under the non-ideal optical conditions has been investigated. The experimental results agree well with the expected values of Doppler frequency shift given by simulation.

Design of data acquisition system for EAST toroidal field power supply based on LabVIEW

WANG Chuan-dong, ZHU Yin-feng, HUANG Rong-lin, WU Xiao-si, ZHENG Xu, TANG Meng-yu

2022, 42(2): 194-199. DOI: 10.16568/j.0254-6086.202202004

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A real-time data acquisition system based on LabVIEW software and database is designed to realize the real-time acquisition, data processing, storage and historical query of the multi signals of EAST toroidal field power supply system. The results show that the designed system can realize real-time monitoring of the state of the toroidal field power supply.

Leak testing scheme for the gas fueling manifold of ITER gas injection system during on-site assembly

HUANG Xiang-mei, JIANG Tao, LI Wei, LI Bo

2022, 42(2): 200-205. DOI: 10.16568/j.0254-6086.202202005

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According to the leak testing requirements defined in the ITER vacuum handbook, the leak testing scheme for the gas fueling manifold of ITER gas injection system during the on-site assembly was proposed. The inner pipes of the gas injection manifold are leak tested by helium spraying method. According to the welding sequence of the port cell, it will be implemented when the welding work of a pipe in each port cell is finished. The maximum pumping time and response time required by the inner pipe leak testing are estimated and results show that maximum pumping time is less than 30 min and response time is less than 10 min for single leak test. The guard pipe of the gas fueling manifold is leak tested by helium sniffing method, which is implemented after all the welding work of the guard pipe is finished.

Design and test of superconducting joint for ITER calibration field magnet

ZHANG Biao, ZHENG Jin-xing, WANG Lin, LU Kun, WEI Jing

2022, 42(2): 206-206. DOI: 10.16568/j.0254-6086.202202006

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A superconducting connector for ITER correction coil is designed to realize low resistance connection between superconducting cables. The structure of the correction field superconducting joint and superconductor is introduced, the direct resistance of the joint is calculated, and the reasonable manufacturing process is determined. The test resistance of joint sample is 1.4nΩ, lower than the design value of 5nΩ.

Design and pressure drop experiment of helium tube for ITER bottom correction coils

YIN Zhong-hui, MA Qiang, ZHENG Jin-xing, WANG Lin, LU Kun, WEI Jing

2022, 42(2): 210-215. DOI: 10.16568/j.0254-6086.202202007

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The structure composition of cable conductor and helium tube for ITER bottom correction coils (BCCs) is presented, and its pressure drop experiment is carried out. The results show that the flow state of gas is affected by friction in flow channel at low flow rate. At large flow rate, the relationship between friction coefficient and Reynolds number corresponds to that obtained by the standard sample experiment, and the flow resistance of complete BCC tube accords with the theoretical design value.

Design and development of monitoring system of vacuum leak detection based on configuration software and multi-serial communication

XU Jie, TIAN Pei-hong, LUO Shan, LU Yong, ZHANG Long, CAI Li-jun

2022, 42(2): 216-222. DOI: 10.16568/j.0254-6086.202202008

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A man-machine interface for monitoring was developed with KingView software and the monitoring system of vacuum leak detection system was designed based on KingView serial communication. The screen drawing, variable definition, communication configuration, scripting, data report query and storage of the higher-level configuration software were described. At the same time, the polling program for multi-serial port devices was designed, and the monitoring system was developed and successfully applied in HL-2M tokamak.

Research on microstructure and mechanical properties of 316L/RAFM steel electron beam welding butt joints

FAN Xiao-song, , ZHANG Yong, SHEN Xu, , MA Jian-guo, LIU Zhen-fei, LIU Zhi-hong, WU Jie-feng

2022, 42(2): 223-228. DOI: 10.16568/j.0254-6086.202202009

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The electron beam welding processes of 316L/RAFM steel at the welding parameters 150kV/39 mA were explored, and the microstructure and mechanical properties of the joints were tested and analyzed. An effective welding depth of 18mm was achieved in the presence of magnetic deflection and the well-welded joint properties were obtained.

Research on soft X-ray camera signal self-test using laser diode

ZHOU Run-hui, CAO Hong-rui, , ZHAO Jing-long, LIU Shi-xing, ZHANG Wei, LI Qiang, CHEN Kai-yun, YU Hong, HU Li-qun

2022, 42(2): 229-235. DOI: 10.16568/j.0254-6086.202202010

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Remote signal self-test function of radial X-ray camera in ITER is realized using laser diode. The optical path between detector and laser diode is designed with diffuse plane, the driving circuit module with real-time response function is designed based on the field programmable gate array (FPGA), the design of remote switching, controlling output luminous intensity and current-limiting protection is achieved with LABVIEW software, and the control accuracy reaches one thousandth levels. The function of sending a narrow pulse current signal is reserved in the FPGA code, and the narrowest pulse reaches within 100ns, which can be used to measure the response rate of detection system, and measure the background noise and baseline offset.

Investigation on the effect of buoyancy on the subcooled flow boiling heat transfer characteristics of in tube waters

LUAN Zhen-bo, ZHOU Zhan-ru, HUANG Sheng-hong, YE Min-you

2022, 42(2): 236-243. DOI: 10.16568/j.0254-6086.202202011

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Based on the known experimental data of 2087 groups of subcooled flow boiling heat transfer of water, the influence of buoyancy on their performance in different flow directions and heating modes were discussed with the relationship between Nusselt number(Nu) and Grashov number(Gr). Experimental study on subcooled flow boiling heat transfer in a horizontal rectangular tube with unilateral heating of the upper wall was carried out. The experimental results show that the upward buoyancy hinders the diffusion of bubbles into the fluid, which makes the heat transfer worse. Under the conditions of increasing flow velocity, increasing pressure and decreasing subcooling degree, Nu increases with Gr, which enhances the subcooled flow boiling heat transfer.

Spectral analysis on multi-channel motional Stark effect diagnostic on EAST

YU Qing-jiang, LÜ Bo, FU Jia, CHEN Jun, CHEN Dong, LI Yi-chao, ZHANG Hong-ming, LI Ying-ying, WANG Fu-di, YE Min-you

2022, 42(2): 244-249. DOI: 10.16568/j.0254-6086.202202012

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By fitting Dα spectral lines in EAST plasma measured by Multi-channel motional Stark effect (MSE) system, Stark splitting spectrum is obtained, therefore the magnetic field distribution is calculated. The result is in agreement with the magnetic field value from the coil currents with about 5% deviation.

Numerical simulation of lower hybrid current drive in CFETR

WU Chen-bin, , DING Bo-jiang, LI Miao-hui, LI Yong-chun, , WANG Yun-fei, , YAN Guang-hou, , Yves Peysson

2022, 42(2): 250-256. DOI: 10.16568/j.0254-6086.202202013

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Based on ray tracing code and Fokker-Planck equation code, the dependence of driving current and power deposition position on lower hybrid (LH) wave polar injection position and parallel refractive index spectrum is studied on CFETR. The influence of nonlinear effect of lower hybrid wave at the plasma edge on current driven and power deposition is discussed. An optimized value of LH wave parallel refractive index and injection position is given. The preliminary numerical calculation shows that the nonlinear effect will reduce the driving current in both high field side and low field side, and the difference between high field side and low field side is about 6%, which is less than the difference (~25%) when considering the nonlinear effect.

Two-dimension electrostatic particle-in-cell simulation of two-stream instability

ZHAO Bing-yan, CHEN Zong-hua

2022, 42(2): 257-263. DOI: 10.16568/j.0254-6086.202202014

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In order to study the evolution process of two-stream instability in two-temperature electron plasma, two-dimensional electrostatic particle-in-cell simulation was conducted, where Poisson equation was solved by relaxation iteration method, and the code satisfied the conditions of charge conservation, momentum conservation and energy conservation. In the nonlinear evolution process of electron two-stream instability, the cavity structure in phase space was obtained, and the electron cavity appeared correspondingly in real space. The growth rate of instability and the corresponding dispersion relation were given.

Modeling and control of HL-2A plasma horizontal displacement based on neural networks

FU Xian-fei, YANG Bin, , WANG Shi-qing,

2022, 42(2): 264-270. DOI: 10.16568/j.0254-6086.202202015

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Based on the gated recurrent unit (GRU), the network topology of the prediction model is built, to train and test the response model of the HL-2A plasma horizontal displacement system. The test results show that the fitting degree of 43% of the sample data exceeds 0.8. Using the network model as the controlled object, an HL-2A plasma horizontal displacement MRAC system is designed with a model reference adaptive control (MRAC) algorithm based on radial basis function (RBF) neural network. The simulation results show that the output response of the control system can quickly track various input reference signals. The controller can control the horizontal displacement of the plasma and has strong anti-disturbance capability.

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