Table of Content

15 April 2020, Volume 40 Issue 1

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Plasma Physics

Two-dimensional gyrokinetic integral eigenmode equation for drift instabilities in tokamak

WANG Ling-feng, DONG Jia-qi

2020, 40(1):  1-7.  DOI: 10.16568/j.0254-6086.202001001

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Based on Vlasov equation, a set of two dimensional gyrokinetic integral eigenmode equations for drift instabilities in tokamak plasmas is derived. All kinetic effects of ions, including transience parallel to magnetic field, drifts induced by curvature and gradient of magnetic field, and effect of finite Larmor radius are included. Not only the radial structure but also the coupling of neighboring poloidal modes induced by toroidicity of the magnetic field and poloidal structure of the modes may be obtained from these equations, in contrast to ballooning mode representation treatment which can give mode structure along magnetic field lines only. The equations provide theoretical bases for relevant numerical simulation investigation.

The dynamic transport equation of impurity ion in magnetic confinement plasma

TIAN Yin, LIU Xiang, ZHENG Peng-fei

2020, 40(1):  8-15.  DOI: 10.16568/j.0254-6086.202001002

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On the basis of the non-equilibrium statistical theory, the transport equations of various impurity ions, deuterium ions and electrons, namely the special multi-component plasma, were derived from Fokker-Planck kinetic equation. The transport dynamics of impurity ions with Zth-level charges forming in the various ionization levels and the contribution of explicit collisions between different particles were systematically analyzed. In addition, the obtained transport equations of various impurity ions are more compact and elegant.

Preliminary analysis of HL-2M hybrid operation scenario

XUE Miao, ZHENG Guo-yao, XUE Lei, LI Jia-xian,HUANG Wen-yu, XIE Jin-yu, JIAN Xiang, CHEN Jia-le

2020, 40(1):  16-22.  DOI: 10.16568/j.0254-6086.202001003

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The physics analysis of hybrid operation scenario for the new medium-sized tokamak HL-2M under construction is simulated, based on OMFIT integrated modeling framework. Under the condition of plasma current of 1MA and toroidal magnetic field of 1.88T, a hybrid operation scenario is achieved with a flat core q profile around 1 by implementing the auxiliary heating and current drive of electron cyclotron wave (ECW) and neutral beam injection (NBI). In this case, the fractions of ohmic current and bootstrap current are 26% and 42% respectively, and the energy confinement factor H_98,y2 is as high as 1.19. In order to obtain a higher normalized beta βN under the condition of hybrid operation, a counter injection of NBI must be added. Moreover, optimizing off-axis ECCD and increasing on-axis NBI power can contribute to fully non-inductive hybrid operation, in which the β_N is 3.47, H_98,y2 is 1.14 and bootstrap current fraction is 51%.

Research on GPU parallel acceleration of digital harmonic analysis algorithm for motional Stark effect diagnostic on EAST

ZHI Yu-qin1, 2, HUANG Yao1, FU Jia1, CHEN Ying1, WANG Feng1, YU Qing-jiang1, 2, LI Ying-ying1, WU Zhen-wei1, WAN Bao-nian1, Lü Bo1

2020, 40(1):  23-27.  DOI: 10.16568/j.0254-6086.202001004

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The parallel acceleration of digital harmonic analysis (DHA) algorithm is realized by using the CPU and GPU isomerization model in the data processing for motional Stark effect (MSE) diagnostic system on EAST. This model makes full use of the advantage of GPU parallel computing to complete the calculation process of Fourier transform and other calculation process that has high calculation efficiency and powerful parallelism. The CPU performs logical operations such as data access and process control. Compared with the serial DHA algorithm, the parallel one achieves more than 2000 times acceleration, which can meet the requirements of timely data processing during MSE diagnostic experiments.

Numerical simulation of velocity and temperature fields of the argon inductively coupled plasma

MA Li-bin, YU Ming-hao, LIU Kai

2020, 40(1):  28-33.  DOI: 10.16568/j.0254-6086.202001005

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In order to obtain the flow-field properties of the inductively coupled plasma wind tunnel (ICPWT) for the research of the thermal protection system (TPS) of re-entry vehicles, a non-equilibrium numerical model with the coupling of flow-field, electromagnetic-field and chemical-field was established to simulate radio-frequency discharge, Joule heating phenomenon and ionization/dissociation chemical process of an ICP flow. Distribution characteristics of flow velocity and temperature were obtained and analyzed under different inlet mass flow rates and different working pressures. Calculation results show that the velocity on the center line of the plasma torch increases with the increase of the inlet mass flow rate, but decreases with the increase of the working pressure. At the same time, the temperature on the center line of the plasma torch decreases as the inlet mass flow rate increases. However, the temperature decreases first, and then increases as the pressure increases. This research will provide reference for the optimal design of high thermal efficiency ICP torch and guidance for industrial applications of the inductively coupled plasmas.

Nuclear Fusion Engineering and Technology

Tritium start-up inventory and tritium balance analysis of China Fusion Engineering Testing Reactor

WANG Jun, WANG Xiao-yu

2020, 40(1):  34-39.  DOI: 10.16568/j.0254-6086.202001006

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Based on reactor core design parameters and the flow chart of the fuel system of China Fusion Engineering Testing Reactor (CFETR), a tritium transfer model of each subsystem in the fuel system is established by means of the average residence time method, and the transport process of tritium flow and detention between each subsystem is described. According to the design parameters, the impact of the fusion power level, duty factor, and the tritium burn-up ratio on tritium balance and start-up tritium inventory of CFETR is simulated.

Structural dynamics analysis of HL-2M divertor

ZHANG Wang1, 2, YUAN Ying-long2, YAO Lie-ming1,SHEN Jun-tian1, 2, CHEN Ya-jing1, WU Jing1

2020, 40(1):  40-44.  DOI: 10.16568/j.0254-6086.202001007

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The dynamic response of the divertor under dynamic load is analyzed with the finite element software. The dynamic amplification factor of the load is determined by comparing the dynamic results with the static results. The results show that the design meets the requirements of the design criterion under the transient electromagnetic force load.

Simulation study on overcurrent protection strategy of the rectifiers for HL-2M central solenoid power supply system

LI Chen, LI Wei-bin, WANG Ya-li, LI Qing, WANG Ying-qiao, CHEN Jun-hong, XUAN Wei-ming

2020, 40(1):  45-51.  DOI: 10.16568/j.0254-6086.202001008

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The model for HL-2M central solenoid (CS) power supply system is built with the MATLAB simulation tool. Based on the model, the overcurrent protection strategy of the converters is studied. According to the simulation, an optimal overcurrent protection strategy is established for the converter in the CS power supply system, which provides a theoretical basis for the safe and reliable operation of the CS power supply.

Plasma feedback control system of HL-2M tokamak

ZHOU Jian, REN Lei-lei, SONG Xian-ming, ZHENG Guo-yao,ZHANG Jin-hua, LUO Cui-wen, LI Jia-xian, LI Bo

2020, 40(1):  52-58.  DOI: 10.16568/j.0254-6086.202001009

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Through the analysis of the parameters of the poloidal field (PF) coils and the control requirements of the first plasma discharge on HL-2M tokamak, the advanced control integration technology based on the real-time system and reflection memory (RFM) is adopted to design the first plasma control system (PCS) on HL-2M device. The new system realizes the stable 1ms control period and real-time data transmission and solves the real-time control period and data transmission delay. The experimental results show that the new PCS can meet the current control requirements of PF coils for the first plasma.

Effect of post-weld heat treatment on impact toughness of MAG weld metal of austenitic stainless steel for fusion reactor

SUN Zhen-chao, LI Peng-yuan, ZHANG Teng, CHEN Hui, XU Dan, DENG Hua-lin, KANG Dao-an, LUO Rong-rong

2020, 40(1):  59-64.  DOI: 10.16568/j.0254-6086.202001010

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After heat treatment of metal active gas arc welding (MAG weld) joints of 316LN austenitic stainless steel for fusion reactor at different temperatures, Charpy impact test at liquid nitrogen temperature was carried out. The effects of heat treatment temperature on microstructure, fracture morphology and precipitates were studied with optical microscope, SEM and EDS analysis. Results indicated that the impact toughness of weld metal could be significantly improved by 873K heat treatment. However, with the rising of heat treatment temperature, the precipitates were generated gradually along the grain boundary and a gradual decrease of toughness occurred as well. All fracture was ductile. The dimple became shallow and less with the increase of temperature. Spherical and irregular precipitates were found at the bottom of the dimple. The spherical precipitates generated during welding were free from the influence of the heat treatment, and the irregular precipitates increased with the rising of temperature. High content of Mo in filler materials led to a great segregation of Mo at the grain boundary, which would promote the precipitation of σ phase. Impact toughness of weld metal decreased significantly when continuous distribution of σ phase formed at grain boundary.

Preliminary design of pipe joint assembly type ITER enhanced heat load first wall

WU Jing, WANG Ping-huai, CHEN Ji-ming, YUAN Tao,ZHU Xiao-bo, LI Qian, GAO Hui, KANG Wei-shan

2020, 40(1):  65-71.  DOI: 10.16568/j.0254-6086.202001011

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ITER first walls (FWs) undertaken by China adopt a large number of welded joint structures, the cooling channel contains many welds which lead to high risk of leakage of cooling water, and there are key problems such as difficulty for replacement of the defective parts in the welding assembly. Based on the results of semi-prototype research and development, it needs to be changed and redesigned in the stage of full-scale prototype (FSP) manufacturing process qualification. Design key point is that the fingers adopt fixed structure of front dovetail slot and middle screw connection, and the finger pair adopts front welded pipe connection and middle pipe connector welded with central beam to form an internal cooling channel circuit. The structural thermal and elastoplastic analyses of the preliminary design model are carried out. The analysis results show that its temperature, displacement and strength are in the acceptance range. This structure can be used to further detail design of enhanced heat load first wall.

Distributed data acquisition and dual-mode management system based on ethernet

REN Lei-lei, ZHOU Jian, LUO Cui-wen, PAN Wei, MA Rui, LI Jia-xian

2020, 40(1):  72-78.  DOI: 10.16568/j.0254-6086.202001012

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In order to solve the problems of scattered layout of the data acquisition system and easily attenuated and interfered signals in the HL-2M diagnostic equipment, a novel ethernet distributed data acquisition system and a management scheme are present. The acquisition module has an ethernet interface, which can be distributed in the remote distance and connected to the local area network easily. The functions of data acquisition, storage, upload and centralized management can be achieved in the centralized management system, which works in the client/server and different levels management mode, through using the technology of multi-thread socket network communication. The discharge experiment tests prove that the acquisition system has the characteristics of accurate measurement, strong anti-interference performance, fast speed data transmission, convenient deployment and management, and can satisfy the data requirement of plasma physics diagnosis system.

Three-dimensional tolerance analysis of China Fusion Engineering Test Reactor vacuum chamber based on CETOL platform

GUO Liang-liang1, SUN Jin-xin1, LIU Su-mei1, 2, LU Ming-xuan2, NI Xiao-jun2, SHI Ming-ming2

2020, 40(1):  79-84.  DOI: 10.16568/j.0254-6086.202001013

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The tolerance analysis of China Fusion Engineering Test Reactor vacuum vessel is performed using the CETOL tolerance analysis software based on the CATIA platform. Based on the three-dimensional solid model, the assembled targets of the vacuum vessel are simplified and subdivided. Tolerances are assigned according to the overall assembly requirements of the vacuum vessel, and tolerance analysis models are established. The critical dimensions affecting the target tolerances have been determined through the sensitivity and contribution, and the unreasonable tolerances have been redistributed to meet the tolerance requirements of the component, which is very useful to ensure the assembly quality of the vacuum vessel.

Non-Fusion Plasma Applications

Study on gas injection characteristics of a fast electromagnetic valve in electromagnetic plasma accelerator

GUO Hai-shan, YANG Lan-jun, LIU Shuai

2020, 40(1):  85-89.  DOI: 10.16568/j.0254-6086.202001014

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In the measurement of a fast solenoid valve with short injection duration and high gas mass injection, the gas stagnation pressure is measured at the outlet of the solenoid valve using a high frequency pressure sensor, and the injected gas mass is measured by the vacuum chamber pressure difference before and after the gas injection. Studies show that driving current, displacement limits, and background air pressure have a significant effect on gas injection characteristics. When the valve plate electromagnetic force is much larger than the resistance caused by the background air pressure, the increase of the driving current and the background air pressure accelerate the gas flow in the flow channel and increase the gas injection mass. When the maximum gas flow rate exceeds the local sound speed, the flow channel should be tapered, and the flow channel length should be as short as possible. The gas injection duration is mainly determined by the valve plate movement time and the gas diffusion rate in the flow channel after the valve closes.

Investigation on static and high speed characteristic of a plasma actuator

YIN Ning, TAN Hui-jun, LIANG Gang, HUANG He-xia, SUN Shu

2020, 40(1):  90-96.  DOI: 10.16568/j.0254-6086.202001015

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A parametric study of high-frequency plasma jet actuator was carried out, using the experiment- tally measured energy distribution law of arc discharge as an ideal heat source. The influence of the exit angle of the actuator on the flow field was explored. The jet flow field characteristics of the spark discharge actuator under supersonic flow (Ma0=2.0) were investigated. The results show that the energy density of heat flux increases and the jet front and forward shock wave moves faster with the decrease of discharge region, and the smaller the exit angle of the jet is, the stronger the momentum injection ability of the actuator along the flow direction is. The rule still applies under high-speed air flow conditions. Compared to the static condition, the momentum injection capability of the jet is stronger and the influence domain is larger under supersonic flow conditions.