Table of Content

15 March 2021, Volume 41 Issue 1

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Plasma Physics

Experimental observation and simulation verification of reverse shear Alfvén eigenmodes on HL-2A tokamak

SUN Hao-fang, SHI Pei-wan, CHEN Wei

2021, 41(1):  1-7.  DOI: 10.16568/j.0254-6086.202101001

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Using AMC program, the frequency variation characteristics of reverse shear Alfvén eigenmodes 
(RSAE) under different safety factors are obtained. When the minimum of q-profile q_min >1, the frequency of 
RSAE increases with the increase of q_min , and the frequency of RSAE increases with the decrease of q_min when 
q_min <1, which is consistent with the frequency given by simplified RSAE dispersion relation. In HL-2A 
experiment, the up-sweeping mode was found in the case of q_min >1 and q_min <1 during the current ramp-up and 
sawtooth phase, respectively. The frequencies of these modes are between the toroidal Alfvén eigenmodes and the 
beta-induced Alfvén eigenmodes, which are identical with the frequency of the RSAE modes obtained with AMC. 
The radial mode structure consists of a single poloidal harmonic wave and is highly localized nearby q_min , which 
is the typical characteristics of RSAE. 


Parallel computing of magnetohydrodynamic simulations based on conservative perturbed model

TAN Yao, , MA Jun, XIANG Nong

2021, 41(1):  8-15.  DOI: 10.16568/j.0254-6086.202101002

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Based on the conservative perturbed model, the nonlinear magnetohydrodymamics code in 
two-dimensional slab geometry is developed. It applies the flux vector splitting method and the mapped weighted 
essentially non-oscillatory reconstruction scheme. Numerical tests of the ideal Kelvin-Helmholtz instability and 
the resistive single tearing mode show its capability and high accuracy in solving linear and nonlinear MHD 
instabilities. To run the code on the computer cluster, a parallel computing architecture based on the MPI and 
OpenMPlibraries is developed. In the process of parallel computing, load balancing is used to dynamically 
allocate the computing amount of each node, which improves the computing efficiency. 


Particle simulation of heat deposition on the ITER-like divertor tile surface

HU Wan-peng, CAI Lai-zhong

2021, 41(1):  16-20.  DOI: 10.16568/j.0254-6086.202101003

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Heat flux distribution near the poloidal gap of ITER-like divertor plate castellated with small 
monoblock tiles inclined to the surface along the toroidal direction is simulated with a particle simulation code, 
HEDPIC. The effect of beveling height on the heat flux distribution is investigated. The results show that when 
the tile is set at an appropriate tilt angle, the electron heat flux density on the upper surface near the gap is zero, 
and the ion heat flux is less than that of the upper surface away from the gap. Therefore, the high heat flux 
problem of tile edge is solved. 


Research on quasi two-dimensional MHD turbulence model of liquid blanket in fusion reactor 

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

2021, 41(1):  21-25.  DOI: 10.16568/j.0254-6086.202101004

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In order to study the turbulent magnetohydrodynamic (MHD) effect of liquid metal in the tritium 
breeder blanket of fusion reactor, a new quasi two-dimensional one equation MHD turbulence model is developed 
in this paper, and the relevant numerical simulation program is made and verified. For the quasi two-dimensional 
MHD turbulent flow in a rectangular tube, the three-dimensional flow mainly occurs in the Hartmann layers, and 
the main flow area in the center presents two-dimensional flow. In order to reflect this special flow feature, the 
new turbulence model removes the traditional dissipation term from the standard k-ε model and instead uses the 
electromagnetic dissipation term to simulate the turbulent MHD effect. At the same time, Bradshaw hypothesis is 
used to model the turbulence eddy viscosity. In order to verify whether this turbulence model is reasonable, a 
numerical simulation program is made, and the program is corrected by using the results of direct numerical 
simulation (DNS). The results of numerical simulation are in good agreement with those of DNS. In general, the 
turbulence model can be applied to the numerical simulation of MHD turbulent flow in the liquid blanket of 
fusion reactor. 


Development of high speed monochrome imaging system on J-TEXT tokamak

ZHANG Wei-wei, CHENG Zhi-feng, ZHANG Xiao-long, JIAO Shao-dong, ZHANG Xiao-yi, J-TEXT team

2021, 41(1):  26-32.  DOI: 10.16568/j.0254-6086.202101005

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The high-speed monochrome imaging system on J-TEXT tokamak was developed to study the 
relationship between plasma impurity behavior and magnetohydrodynamics (MHD) instability. Intensity 
distributions of carbon impurity radiation (CV 227.09nm, CIII 464.7nm) were simulated with STRAH code. The 
optical path structure of the system was designed with fiber coupling method, whose survey range is 0.3a-0.95a 
(minor radius) on the high field side and its spatial resolution is 1.3cm. A photomultiplier tube (PMT) is selected 
as detector, whose output current signal is amplified with transimpedance circuit and active filter circuit with 10 
microseconds of time resolution in 100kHz bandwidth. The experimental results show that the evolution of carbon 
impurities is surveyed under plasma discharge with MHD instability. 


Nuclear Fusion Engineering and Technology

Design and performance test of thermal transfer structure of first wall on HL-2M tokamak

LIU Jian, LAI Chun-lin, WANG Jin, LIN Tao, CAI Li-jun

2021, 41(1):  33-36.  DOI: 10.16568/j.0254-6086.202101006

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In the design of thermal transfer structure of first wall on HL-2M tokamak, the heat loads on first 
wall surface facing plasma are transferred rapidly to the vacuum vessel wall by using the characteristic of fast heat 
transfer in direction of the heat pipe axis. As the cold-heat connection ends, the heat sink is welded respectively on 
the backboard of first wall and vacuum vessel wall, while the heat pipe is embedded into the heat sink. The metal 
foil is inserted into the gap between the pipe and the sink for heat transfer enhancement, and is fixed by a keep 
plate to enhance the heat transfer of the contacting interface. A testing prototype according to the heat transfer 
structure design is manufactured. The performance of prototype of heat transfer structure is tested. It shows that 
the maximum heat transfer power is 4kW and the maximum equivalent convective heat transfer coefficient is 
6kW·m^‒2 between the cold end and heat end of the prototype under the experimental and theoretical extrapolation 
conditions. 


Preliminary design and analysis of CFETR He-cooled divertor 

HUANG Wen-yu, LU Yong, ZHANG long, LIU Kuan-cheng, JIN Yu-zhong, ZHENG Guo-yao, CAI Li-jun, ZHU Yun-peng, XUE Miao

2021, 41(1):  37-44.  DOI: 10.16568/j.0254-6086.202101007

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Based on the configuration of divertor of China fusion engineering test reactor (CFETR), T-type, 
finger-like and slab models of He-cooled divertor were preliminarily designed. Under the condition of 10MPa 
inlet helium pressure and 10MW⋅m−2 steady-state heat load, numerical analysises of their heat transfers were 
carried out. By optimizing the structural design and inlet helium parameters, the working temperature of the target 
plate was reduced and the ability of the target plate to handle high thermal load was improved. Under the 
steady-state heat load of 20MW⋅m−2, the optimized elementary units of T-type and finger-like structures were 
analyzed. Consequently, the preliminary structure of hybrid CFETR He-cooled divertor was proposed. 


Electromagnetic-structural coupling analysis of CFETR water cooled blanket 

WANG Kai-song, YANG Hao, XU Kun

2021, 41(1):  45-50.  DOI: 10.16568/j.0254-6086.202101008

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The electromagnetic analysis of the water cooled ceramic breeder (WCCB) blanket in the high 
field side on China Fusion Engineering Test Reactor (CFETR) was calculated by Maxwell. The electromagnetic 
load of the blanket under the linear 36ms attenuation of plasma current was obtained. The deformation 
displacement and the equivalent stress of the blanket were calculated by using the load transfer coupling method 
and ANSYS. The results show that the maximum equivalent stress of the WCCB blanket meets the design 
requirements, and the deformation displacement is within the allowable range, which preliminarily verifies the 
rationality of the blanket structure design. 


Preliminary research on the structure of CFETR inner thermal shield

HUANG Chao, HOU Bing-lin, ZHANG Teng, XU Wan-yun, LAI Xiao-qiang

2021, 41(1):  51-55.  DOI: 10.16568/j.0254-6086.202101009

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Based on several existing models of thermal shield structures in fusion device, an option design 
scheme for CFETR vacuum vessel thermal shield (VVTS) is proposed, which is to drill some cooling channels 
along the direction of thickness of the VVTS panel. A parallel and series connection flow path is designed for 
every inner thermal shield part. The temperature distribution of different parts of CFETR VVTS is calculated with 
finite element method. The result shows that the temperature distribution of new option is more uniform, and the 
effect of cooling is better. By means of the deep hole drilling, the maximum surface emissivity can be improved 
from 0.05 to 0.075 at a similar output radiant power. Therefore, the materials of the silver coating can be replaced 
by low activation and low surface emissivity elements such as chromium and tungsten. 


Calculation and analysis of PSM high voltage power system module 

XIA Yu-yang, LI Qing, MAO Xiao-hui, WANG Ya-li

2021, 41(1):  56-60.  DOI: 10.16568/j.0254-6086.202101010

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The output voltage of the three-phase uncontrolled rectifier circuit containing LC filter of 
high-voltage power supply system for the lower hybrid current drive is analyzed and the relationship between the 
output voltage and the circuit parameters is obtained. The three-phase uncontrolled rectifier circuit is simulated on 
the MATLAB/Simulink platform, and the waveform of the output voltage is obtained. It is observed that the 
output waveform meets the design requirements of the power supply system. 


Investigation on the microstructure and mechanical properties of carbide dispersion strengthened steel

YANG Shuang, CHEN Ji-ming, FU Hai-ying, WANG Ping-huai, WANG Jian-bao, ZHANG Li-wen, CHAI Zong-jian, ZHANG Ming

2021, 41(1):  61-66.  DOI: 10.16568/j.0254-6086.202101011

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Microstructure and mechanical properties of carbide dispersion strengthened (CDS) steels 
fabricated by mechanical alloying are investigated. After 60 hours' ball milling, the solid solution process of main 
alloy elements was completed. At the same time, the added carbide particles significantly improve the tensile 
mechanical properties. The strength and hardness of the materials are obviously higher than that of CLF-1 steel. 
The elongation and fracture morphology of CDS steels also indicate a fairly good result of ductility. 


Experiment observation for glow discharge with gap insulation electrode 

ZHANG Qi, WANG Ming-xu, LI Bo , WANG Ying-qiao, PAN Li , LIU Hao , GU Zheng-yang, ZHANG Bo, FANG Tong-zhen, HE Kai-hui, HE Fang

2021, 41(1):  67-71. 

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In order to determine the gap sizes of electrode insulation for ITER glow discharge wall 
conditioning (GDC) and to assess the heat load deposited on the electrode head during the glow discharge, a series 
of tests were performed on the SWIP experimental platform. The breakdown voltage against H₂ and He glow 
discharge was obtained. The glow discharge voltage and thermal load on the test electrode against pressure, the 
tolerance of the test electrode in glow initiations, the relationship between the test electrode temperature and heat 
load, and gas pressure of glow discharge in different regions were studied under the ITER wall ion current density. 
In addition, ion sputtering and deposition on the wall of vacuum chamber during discharges were introduced, and 
their effects on the gap insulation were preliminarily analyzed. These results can provide reference for design and 
operation of ITER glow discharge wall conditioning system. 


 Topology design and analysis of high field magnetic resonance superconducting magnet power supply

DAI Tian-li, , ZHOU Chao, QIN Jing-gang, LI Jian-gang, GAO Ge

2021, 41(1):  72-77.  DOI: 10.16568/j.0254-6086.202101013

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The power supply of high field magnetic resonance superconducting magnet in a large aperture 
human body imaging system works in two aspects, i.e. normal excitation and demagnetization. The 
demagnetization energy is returned to the power grid through the "inversion" of the power supply. According to 
the design requirements, two kinds of energy feedback topologies are analyzed and compared. The proposed 
topology is analyzed and simulated with the Matlab/Simulink analysis.


A detection method applied in narrow bandwidth inter-harmonics of tokamak power supply 

TIAN Yun-xiang, XU Liu-wei, ZHANG Jun-min, LI Jun, WU Ya-nan, SHEN Xian-shun, , LU Jing

2021, 41(1):  78-84.  DOI: 10.16568/j.0254-6086.202101014

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A hybrid detection algorithm based on F42N150 single-frequency analog notch filter with 
Q-factor and elliptic digital bandpass filter is analyzed to solve the detection problem of low-frequency harmonics 
in tokamak power supply. The fundamental and 5th-order harmonic, viewed as interference signals, can be 
eliminated by boundary optimization of the elliptic digital filter to achieve effective spectrum separation. The 
design process is optimized by simulation with MATLAB and the validity of the detection algorithm is verified by 
experiments with digital analysis system based on digital signal processing (DSP). 


Study on cutting first wall tungsten material for fusion reactor by premixed abrasive jet 

WANG Yan, , , ZHANG Xi-yang, ZHOU Zi-bo, , YAO Da-mao

2021, 41(1):  85-90.  DOI: 10.16568/j.0254-6086.202101015

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The experiment of tungsten cutting with pre-mixed abrasive jet is carried out to solve the problem 
of tungsten difficult to machine for first wall in fusion reactor. The surface morphology of the cut surface is 
studied, and the effects of jet pressure and cutting speed on the surface roughness and the depth of the smooth 
zone of the cut surface are analyzed. The results show that cutting speed has a great influence on the roughness, 
and cutting speed can reduce the roughness of the cut surface. The influence of jet pressure on the roughness is 
slightly smaller than that of the cutting speed, and the increase of jet pressure can increase the depth of smooth 
area of cut surface and improve the quality of cut surface. It is found that there are trailing marks, residual wedge 
angle and erosion pits on the cutting surface, which need to be suppressed or eliminated by nozzle angle 
compensation to improve the processing quality of the cutting surface.


Non-Fusion Plasma Applications

Design of high efficiency solid state power source for radiofrequency plasma light 

JIA Hua, SHAN Jia-fang, LIU Fu-kun, HUAN Wei-ding

2021, 41(1):  91-96.  DOI: 10.16568/j.0254-6086.202101016

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A high efficiency driving power source with capability of withstanding high load mismatch has 
been developed for the radiofrequency (RF) light emitting plasma (LEP) sources. Considering open-circuit for the 
third harmonic and short-circuit termination for the voltage even harmonics, the circuit topology combining the 
lumped parameter and the distributed parameter is used to realize the high efficiency class F power amplifier with 
harmonic control. The working frequency controlled by the microcomputer follows the resonant frequency of the 
plasma light to achieve low voltage standing wave ratio (VSWR) for the output of the power amplifier, so that the 
long-term reliability is improved. Both the full power tests with continuous wave and matching test with the 
plasma light were carried out for the high efficiency solid state driving source. Results show that the output power 
of 200W with the drain efficiency of 80.7% or more is achieved for the final stage class F power amplifier in the 
range of 435~445MHz. The overall efficiency of the driving power source is 77.5% within the operating 
frequency range, and the system light efficacy is 86.21m·W⁻¹ in the joint test with the plasma light resonator.