Nuclear Fusion and Plasma Physics

Study of the reflection protection for HL-2A 2MW LHCD system

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

2022, 42(4): 367-371. DOI: 10.16568/j.0254-6086.202204001

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A reflection protection system for HL-2A lower hybrid current drive (LHCD) system was developed to improve its efficiency. The digital signal processing circuit is designed with Verilog hardware description language, and an EPM240T100C4 Complex Programmable Logic Device (CPLD) is selected for digital signal processing. A 14-bit timer is adopted to realize about 3.6ms interval for restarting the LHCD system after the protection happens. The test results show that the protection system meets the design requirements.

Numerical simulation of rotary jet cooling

LIU Ping, ZHANG Man-man, QIN Guang-jin, GUO Yu-sheng

2022, 42(4): 372-377. DOI: 10.16568/j.0254-6086.202204002

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Using ANSYS FLUENT software and RNG k-ε turbulence model, the internal flow characteristics and coupling surface heat transfer characteristics of spiral nozzles with cross-shaped, inner cross-shaped and flower-shaped structures were studied respectively. The numerical results show that the smaller the helix angle θ is, the higher the outlet velocity of the spiral nozzle is, the more concentrated the water flowing out of the nozzle is, and the clearer and more obvious the water movement track is. Under the same working condition, the heat transfer efficiency and heat transfer uniformity of flower-shaped nozzle with the helix angle 30° are higher than those of the two other nozzles. The maximum position of Nusselt number Nu of its coupling surface would gradually be away from the jet center (r/d_j=0, d_j is the equivalent diameter of nozzle) with the increase of Reynolds number Re. With the increase of target distance H, Nu gradually decreases and the swirling effect gradually weakens. When H=2d_j, 4dj, the maximum Nu is located at r/d_j=1, and when H=6d_j, the maximum Nu is located at the jet center (r/d_j=0).

The conceptual design of maintenance and decommission process for the CFETR tritium-generating blanket and divertor in the hot cell

XU Wan-yun, WANG Cai-wang, LUO Rong-rong, HUANG Chao, LI Peng-yuan, XU Fa-yong, DENG Hua-lin, CHEN Hui

2022, 42(4): 378-382. DOI: 10.16568/j.0254-6086.202204003

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For nuclear safety of fusion reactor environment, scheduled full inspection and maintenance, or decommission in the hot cell are required for the blankets and the divertors. Based on the structural characteristics of the two components, the maintenance and decommission process in the hot cell was designed, including key process like radioactive waste treatment, cleaning, tritium decontamination and so on. Besides, by reference to ITER’s design and following the ALARA (As Low As Reasonably Achievable) rule, a radiation level partition of every function region in the hot cell is given.

A new method for remote control of filament power supply for the LHCD system on HL-2A tokamak

WANG Jie-qiong, LU Bo, HUANG Mei, BAI Xing-yu

2022, 42(4): 383-387. DOI: 10.16568/j.0254-6086.202204004

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The filament power supply of the Lower Hybrid Current Drive (LHCD) system on HL-2A tokamak could not be controlled remotely before, so the design and implement of serial communication system based on WinCC ActiveX control MSComm for the filament Power supply of LHCD system was presented. We called the ActiveX control MSComm directly in the Graphics Designer of WinCC and programmed in VBS Global Scripts to realize serial communication. We can use WinCC more flexibly by using the industrial Ethernet network, serial communication and virtual serial port. The LHCD experiments on HL-2A show that the MSComm-serial communication system of filament power supply for LHCD can operate stably and have the perfect function under the complicated electromagnetic environment during the discharge on HL-2A tokamak.

Conceptual design of neutral beam injection system for CFETR

HU Chun-dong, LIANG Li-zhen, XIE Yuan-lai, XIE Ya-hong, WEI Jiang-long , GU Yu-ming , JIANG Cai-chao , XU Yong-jian, , ZHAO Yuan-zhe , CHEN Yu-qing

2022, 42(4): 388-392. DOI: 10.16568/j.0254-6086.202204005

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In order to meet the requirements of plasma heating and current driving in China Fusion Engineering Test Reactor (CFETR), the conceptual design of neutral beam injection system is carried out from three aspects: overall layout, beam transmission system and beam source system. Using the method of parameter calculation, the performance index and basic layout of neutral beam injection system are defined according to the requirements of fusion plasma. The beam transmission performance is evaluated by using the beam transmission spatial distribution program, and the spatial layout structure of each functional component is determined. On this basis, the performance index of the beam source system and the layout mode of the extraction system are determined. Combined with the current research and development progress, the basic technical scheme of the beam source is defined. Through the above work, the design requirements of neutral beam injection system parameter index, beam transmission key size and beam source performance index are formed, which lays a foundation for subsequent engineering design.

Application of real-time control framework based on LabVIEW on J-TEXT

XIE Fei, ZHENG Wei, ZHANG Ming, TANG Chou-yao, XU Xin, YANG Cheng, HE Bo, XU Jia-yu

2022, 42(4): 393-398. DOI: 10.16568/j.0254-6086.202204006

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In order to support the research of the plasma divertor configuration experiment on J-TEXT, a real-time control framework was developed based on the LabVIEW programming language. On J-TEXT, the real-time control framework and the selection of the appropriate NI acquisition card and controller are used to build a single-null position auxiliary power supply-bias power control system for the divertor, and the power supply is tested. The results showed that the power supply can output a current of 2kA within a control period of 1ms, which meets the experimental requirements of the single-null configuration of divertor on J-TEXT. The development of this framework greatly improves the efficiency of building a real-time control system and enhances the readability and maintainability of the control program, providing a complete, simple and easy to expand and transplant real-time control framework for J-TEXT.

Preliminary concept design of the magnet supports for CFETR

HOU Bing-lin, LAI Xiao-qiang, XU Wan-yun, WEI Hai-hong

2022, 42(4): 399-403. DOI: 10.16568/j.0254-6086.202204007

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The preliminary concept design of the magnet supports for the China Fusion Engineering Test Reactor (CFETR) is described, and the design of the magnet supports of toroidal field (TF) and poloidal field (PF) is presented. The analysis is performed by mathematical method and finite element method. The analysis results show that the designed magnet supports of CFETR can meet basically the functional requirements.

Research on the remote upgrade of the program of the fast control power branch controller

HUANG Hai-hong, PENG Lan, WANG Hai-xin

2022, 42(4): 404-409. DOI: 10.16568/j.0254-6086.202204008

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In the remote upgrade of digital signal processing (DSP) control program of fast control power supply for plasma vertical displacement on EAST, a new "second-level boot" structure is proposed by changing the sequential structure of the "second-level boot". This structure does not require the involvement of assembly language and uses C language to write the "second-level boot" program. The structure is also combined with wireless network transmission technology to enable remote upgrading and curing of the program. The experimental results show that the proposed "second-level boot" structure combined with the wireless network is capable of cryptographically upgrading the control power DSP program remotely.

Research on the cooling performance of hypervapotron structure for HL-2M divertor

LI Yun-feng, CAI Li-jun, LU Yong, ZHANG Long

2022, 42(4): 410-417. DOI: 10.16568/j.0254-6086.202204009

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In this paper, a candidate scheme of HL-2M divertor, named the hypervapotron structure module, is analyzed by using ANSYS CFX software. The results show that when the height of the flow channel in the divertor is 6mm, with the fin height of 3mm and the fin thickness of 4mm, the capacity of heat removal is the best. When the heat flux of the target reaches 10MW·m2 , the temperature of the target is blow 700℃, the temperature of the heatsink is blow 300℃, meeting the requirement of design.

VSVPWM neutral-point potential balancing strategy based on fuzzy control

DAI Ming-yan, , XU Liu-wei , WU Ya-nan , SHEN Xian-shun, , YANG Shen-fei , TIAN Yun-xiang

2022, 42(4): 418-425. DOI: 10.16568/j.0254-6086.202204010

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A neutral-point potential balancing strategy based on fuzzy control is proposed to solve the problem of DC neutral-point potential imbalance in NPC three-level inverter. The strategy redefines the virtual space vector so that the virtual small vector does not cause the neutral point potential fluctuation, and introduces the control factor Q into the virtual medium vector, which can inhibit the neutral point potential imbalance. At the same time, a combined fuzzy controller composed of fuzzy controller A and B is designed. The controller can adjust the control factor Q according to the neutral point potential deviation to realize the closed-loop control of neutral-point potential. Simulation and experimental results show that the neutral-point potential imbalance problem of NPC three-level inverter using this strategy can be effectively improved.

Impact of heating power on pellet fueling efficiency on EAST

LI-MENG Man-ni, , HOU Ji-lei , ZUO Gui-zhong , CHEN Yue , LI Cheng-long, , LIU Jian-wen, , YE Kai-xuan, , HUANG Jia, , HU Jian-sheng

2022, 42(4): 426-432. DOI: 10.16568/j.0254-6086.202204011

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This paper introduces the system of pneumatic accelerated deuterium pellet injection and presents the experimental results of fueling efficiency performed by this system on EAST. With the increase of additional heating power from 1MW to 10MW, the fueling efficiency of pellet gradually decreases from 60% to 10% and pellet particles mainly deposit at the plasma edge region due to about 50% reduction of the penetration depth of pellet.

Accident safety analysis of the in-vessel LOCA for CFETR water cooled blanket module

WANG Wen-jia, CHENG Xiao-man , MA Xue-bin , LIU Song-lin

2022, 42(4): 433-439. DOI: 10.16568/j.0254-6086.202204012

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The module #3 of WCCB blanket for CFETR is modeled using RELAP5. Steady-state operation and in-vessel LOCA with different break areas are analyzed. The results indicate that the pressure in the vacuum vessel increases rapidly. In a small-break LOCA, relieving the pressure to the large suppression tank can prevent the vacuum vessel from overpressure after the accident occurs. In a large-break LOCA, the vacuum vessel pressure suppression system (VVPSS) cannot curb the rise in pressure effectively, and the effect is inapparent by increasing the volume of the suppression tanks to reduce the pressure in the vacuum vessel. After the check valves are added on the outlet pipes of manifold, the coolant reverse flow into the vacuum vessel is effectively prevented, so that the pressure in the vacuum vessel is maintained within a safe range without the need to activate the VVPSS.

Numerical simulation of fast ion transport driven by fishbone in toroidal configuration

WANG Yong-qin , HAO Guang-zhou , YU Li-min , MIAO Yu-tian , KE Rui , ZOU Yun-peng , GAO Qing-di

2022, 42(4): 440-447. DOI: 10.16568/j.0254-6086.202204013

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In this work, the influences of the fishbone amplitude and frequency on the fast ion redistribution are investigated. The simulation indicates that the fishbone instability causes serious redistribution of fast ions in both real space and phase space. The fast ion density decreases by ~20% in the core (ψ_p /ψ_w≤ 0.2 ) and increases ~7% at the middle region of magnetic flux ( (ψ_p /ψ_w≤ 0.6，ψ_p /ψ_w≥0.2), where p is the poloidal magnetic flux, and ψ_w is the magnetic flux at the last closed flux surface. Furthermore, by parameter scanning, it is found that the redistribution of fast ions is sensitive to the fishbone frequency in the phase space. In addition, the resonance conditions of fast ions and fishbone instability are analyzed.

Numerical simulation of laminar MHD flows in conducting ducts with deformed parallel walls

YAN Jia-wei, MAO Jie, XIONG Bao-long

2022, 42(4): 448-454. DOI: 10.16568/j.0254-6086.202204014

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In this paper, laminar MHD flows in a normal square duct, a duct with concave parallel walls and a duct with convex ones subjected to a uniform magnetic field are numerically studied using a self-developed solver in the OpenFOAM platform. The velocity distribution and the MHD pressure drop of flows in the three ducts are presented at Re=500, C=0.01 and Ha=500~2000. The results show that the concave or convex parallel walls change the velocity distribution significantly. The pressure drop in duct with concave parallel walls is larger than that in the square duct, while the pressure drop in duct with convex parallel walls is smaller than that in the square duct under the same parameters.

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