Table of Content

15 June 2015, Volume 35 Issue 2

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Plasma Physics

Dispersion function for bump-on-tail distribution of energetic particles

ZHAO Kang, JIANG Hai-bing, HE Hong-da, HE Zhi-xiong

2015, 35(2):  97-102. 

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In general, the energy distribution of energetic particles is bump-on-tail when both the neutral beam injection and electron/ion cyclotron resonant heating are used in tokamak plasma experiment. It is easier to induce instability for energy distribution profile with positive energy gradient regions existing such as the bump-on-tail. Therefore, a new dispersion function is introduced in dispersion relation due to bump-on-tail of the energy distribution. The calculation method of the new dispersion function is studied. T results show that the real and imaginary parts of dispersion functions are odd and even functions respectively. There are 2 to 4 extremes for real parts of the dispersion function and the positions of the extremes are dependent on Δ , the gradient of the energy distribution, whereas there are 1 to 3 extremes for imaginary parts and the positions of these extremes are independent of Δ . Both the real and imaginary parts of the dispersion function go to zero when the arguments of Z_t go to infinity. The calculated values agree very well with those given in dispersion function table when the bump-on-tail distribution goes to Maxwellian distribution.

A novel high accuracy fast algorithm for dispersion relation of plasma antenna

HUANG Ye

2015, 35(2):  103-108. 

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The physical model of the plasma antenna with plasma-insulating tube-vacuum is established. Then the new dispersion relation is derived. Through the geometric interpretation, a new algorithm with high precision and fast convergence is presented. Simulation results verify the correctness and effectiveness of the conclusion. The dispersion relation of cylindrical plasma antenna is studied when the electron density decreases according to the linear law. And the radiation pattern is given. The results have important reference value in analysis and design of the plasma antenna.

Nuclear Fusion Engineering and Technology

Design of power measurement system for LHCD on HL-2A tokamak

WANG He, WANG Chao, LU Zhi-hong, LU Bo, RAO Jun

2015, 35(2):  109-113. 

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A new linear power measurement system composed of logarithmic detectors is designed for LHCD system, which can solve the problems of narrow input power dynamic range and nonlinearity of the power measurement detectors. The measured results indicate that the characteristic curve of new system has a wide dynamic range of power measurement and high linearity. The dynamic input power range is greater than 40dB when the logarithmic consistency error is from −1dB to +1dB. The correlation coefficient of >0.999 is achieved in serviceable ranges using linear fitting. These results are better than previous equipment’s.

Design of the measurement and control system of multi-dimensional loading system for ITER magnet supports

LIAO Min1, LI Peng-yuan1, HOU Bing-lin1, PAN Chuan-jie1, CHI Cheng-fang2

2015, 35(2):  114-119. 

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In order to test the reliability of ITER magnet support structure, the multi-dimensional loading test platform was established for mechanical properties test of support components. The measurement and control system consists of seven sets of EDC controller and board, computer system, 16-channel quasi-dynamic strain gauge, 25 sets of displacement sensors, 7 sets of load and displacement sensors in the cylinders. On the basis of the programmable language, the measurment and control process for the muti-channel loading is realized, and the synchronizing control experiment with high precision for 7 sets of twin-cylinders is accomplished by using EDC220 digital controllers. Under the typical loading conditions, the engineering test result shows that the design of the system is rational, the control system is reliable, and it can guarantee the next requirement of the experiment.

Failure analysis and process improvement of ITER inconel 718 bolts

ZHANG Teng, LI Peng-yuan, XU Dan, HAN Shi-lei, KANG Dao-an

2015, 35(2):  120-124. 

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Chemical composition analysis, metallographic observations, and hydrogen content test was used to inspect raw material properties of ITER inconel 718 bolts. The finite element analysis and the tensile test of the bolts were adopted to investigate mechanical properties of the bolts. Macro and micro observation of bolt fractured surface was used to verify the manufacturing processes of the bolt. The results showed that domestic 718 raw material has meet the property requirements, and the fracture of the bolts was caused by temper brittleness of the rolling layer under the condition of concentrates stress. The results of tensile test of bolts and FEA analysis show that due to the effect of stress concentration, the strength of the bolts was lower than raw material. Meanwhile the strength of bolts decreases with the increase of bolts diameter. Based on the above analysis the new technology was development which can significantly improve the strength of the bolts to 1230MPa, the increment is 160MPa.

Engineering structure design and fabrication process of small sized China helium-cooled solid breeder test blanket module

WANG Ze-ming, HU Gang, CHEN Lu, TAO Hai-yan, CHEN Gao-zhan, YE Xing-fu, WANG Ping-huai, YU De-huai, WANG Shi-zhong, LI Yong, FENG Kai-ming

2015, 35(2):  125-130. 

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As partial verification that the original size module of China helium-cooled solid breeder (CH-HCSB) test blanket module (TBM) was reasonable and the development process was feasible, fabrication work of a small sized module was to be carried out targetably. The detailed design and structure analysis of small sized TBM was carried out based on preliminary design work, fabrication process and integrated assembly process was proposed, so it lay a solid foundation for the engineering fabrication of TBM.

Inverse kinematics algorithm preliminary research for EAST in-vessel viewing 6R manipulators

WEI Xiao-yang1, WANG Kun1, PAN Hong-tao1, 2, ZHAO Wen-long1

2015, 35(2):  131-136. 

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A universal inverse kinematics algorithm which aim is for EAST in-vessel viewing manipulators with coupled articulated structure has been proposed to realize its real-time and high accuracy control. This is to build manipulator kinematics multivariable equations, which can be expressed as a univariate matrix polynomial and solved through getting the eigenvalues of the matrix determinant eventually. Moreover, in order to meet the requirement of programming and actual control of manipulator, positive and inverse kinematics was validated by software developed based on MFC of VC++6.0. The solved instance indicated that the proposed algorithm can obtain all of the inverse kinematics solutions of the manipulators in ms level.

Analysis and implementation of static resonant magnetic perturbation power system for J-TEXT tokamak

NAN Jie-yin, SHI Wen-feng, YI Bing, ZHANG Ming, DING Yong-hua, RAO Bo, ZHUANG Ge

2015, 35(2):  137-142. 

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A pulse power supply system based on capacitor energy storage is developed for the static resonant magnetic perturbation (SRMP) coils on J-TEXT tokamak. SRMP coils of J-TEXT tokamak was introduced and a detailed analysis of the power supply system working principle was given. Its tests and experimental results were provided. The experimental results show that the SRMP power supply system can produce current up to 8kA with maximum current rising rate of 200A.ms^-1, so it can stably produce corresponding magnetic perturbation to support the physical experiments.

Design and implementation of J-TEXT tokamak remote participation system

LI Guang1, 2, ZHANG Ming1, 2, ZHENG Wei1, 2, ZHANG Jing1, 2, LIU Rui1, 2, ZHUANG Ge1, 2

2015, 35(2):  143-150. 

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An open platform for users to participate in J-TEXT tokamak experiment via Internet remotely was designed .The implementation of Web service applies the Representational State Transfer (RESTful) software architecture, developers can use the open API to develop tokamak applications based on their requirements. Authentication and Authorization system protects the open API against hacker attacks. Implementation of J-TEXT tokamak remote participation system based on ASP.NET Web API framework. In the real time data updating area it uses ASP.NET SignalR library to implement multiple server push strategies. The system is flexible and compatible with Experimental Physics and Industrial Control System (EPICS) software. Now it has been already integrated into the J-TEXT Control, Data Access and Communication (CODAC) system. The test and application results show that the system can work continuously and stably, and meet the requirements of tokamak remote participation.

Influence of frequency modulation on the impedence matching of ICRH antenna

TAN Qing-yi, GONG Xue-yu, DU Dan, GUO Zheng-rong

2015, 35(2):  151-155. 

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The liquid triple-stub tuner was adopted to obtain the impedance matching for antenna load of ion cyclotron resonance heating. Under the condition of impedance matching, the frequency modulation technique was used to reduce the reflected power caused by the change of antenna loading. The relationship between reflection coefficient and antenna loading before and after frequency modulation was numerically simulated to everify the effect of frequency modulation on ICRH system impedance matching device. The numerical simulation results show that the liquid triple-stub tuner combine with frequency modulation technique can better reduce the reflection coefficient of transmission system and make the RF power transit antenna radiation coupled to plasma more effectively.

Flow distribution analysis of partial model for WCSB blanket module

WANG Mu-fei, TONG Li-li, CAO Xue-wu

2015, 35(2):  156-162. 

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A verification of the SST turbulence model was conducted according to the flow distribution experiment for WCSB blanket module by JAEA. The simulation model of the first wall in the WCSB blanket module was established to simulate the flow distribution in each cooling tube of the first wall. Calculation result shows that the flow behavior in the first wall model is complicated, and the whole coolant flow area can be classified into main flow and reverse flow area. Respectively, the main flow effects the flow distribution in the cooling tubes mostly, and a series of secondary vortex and toroidal flow exists in the reverse flow. The analysis result shows that the uneven phenomenon of the flow distribution exists in the cooling channels and the difference of the flow rate is less than 2% in the first wall model under all conditions.

Effect of heat flux and liquid lithium velocity on temperature distribution of free flow of liquid lithium

ZHU Zhi-chuan1, ZHANG Chuan-wu1, GOU Fu-jun2, WANG Jian-qiang2,YANG Dang-xiao3, MIAO Feng1

2015, 35(2):  163-169. 

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Commercial software ANSYS CFX are used to calculate the effect of heat flux and liquid lithium velocity on temperature distribution of the free flow of liquid lithium. The calculated results show that the temperature of liquid lithium is higher near the center of guiding groove, the temperature of liquid lithium is lowest in the location corresponding to inlet and outlet of cooling water. The outlet temperature of liquid lithium rises linearly with the increase of plasma heat flux. When the velocity of cooling water is 1.5m·s⁻¹, heat flux are 0.1MW·m⁻² and 1MW·m⁻² respectively, the corresponding temperature of liquid lithium at outlet are 255.3°C and 458.6°C. The temperature of liquid lithium within guiding groove dropped gradually with increase of velocity of liquid lithium, but the amplitude of temperature variation is smaller.

The overall design and preliminary operational results of the liquid lithium loop driven by argon

XUE Xiao-yan1, ZHANG Wei-wei1, ZUO Hao-yi1, OU Wei2, WANG Jian-qiang2,

2015, 35(2):  170-174. 

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In order to study the physical process of the interaction between plasma and free liquid lithium surface, a liquid lithium loop device driven by argon was built. The structural components, technical parameters and operational principle of the loop are mainly introduced, respectively. The loop is mainly constituted of the primary loop, the test section about the plasma interacting with liquid lithium and one cathode linear plasma device. At present, some preliminary simulation and experimental results were obtained in this loop.

Sputtering influence of Tungsten-based plasma facing material induced by surface roughness

YANG Tao, GONG Xue-yu, HU Ji-wen, DU Dan

2015, 35(2):  175-180. 

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Based on experimental results of sputtering of tungsten surface, a model of surface roughness was constructed and the sputter of tungsten surface under the irradiation of high energy H⁺ and He⁺ particles was simulated. The comparison with bipartition model of ion transport theory calculation results was provided. The results show that the sputtering rate decreases with increase of surface roughness of tungsten material. The sputtering rate increases with the particle mass for a certain rough surface and for the same energy of incident particles. These results provide some theoretical support to analyse the impurity level in core plasma of fusion reactors and estimate the lifetime of divertor.

Non-Fusion Plasma Applications

Three-dimensional etching simulation and experiment investigation on cylindrical Hall thruster

LI Hong-bin, TANG De-li, NIE Jun-wei, GENG Shao-fei, ZHANG Fan

2015, 35(2):  181-186. 

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A method combining the numerical simulation and experiment is used to research the cylindrical anode layer hall plasma thruster. Use the method of Monte Carlo method and particle in cell (PIC) was used to simulate the collision and the behavior of plasma in discharge channel, then the physical and numerical model of cylindrical hall accelerator was set up. By simulating the producing and transporting of plasma in discharge area and accelerate area, the mechanism of discharge and accelerate of plasma, and the etching of the pole were obtained. The result shows that, with the increasing of voltage, the etching of inner pole become more serious; the ion energy value in the thruster is about 50% of the discharge voltage value. Meanwhile, measurement of discharge property of thruster in different discharge voltage is also done by experimental method.

Application of infrared nondestructive inspection methods to PFCs

LIU Wen-yong, LIU Lei-lei, TONG Li-li, CAO Xue-wu

2015, 35(2):  187-192. 

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Active infrared thermography test facility was established, non destruction testing (NDT) experiments of EAST W/Cu PFC with different artificial defects size are conducted and infrared thermography imaging is obtained. Surface temperature error of the specimens caused by emissivity can be eliminated by maximum temperature difference reconstruction method, and fast discrete Fourier transform method can increase the ratio of signal to noise and realize defects distinguish. The key factors that may affect this infrared NDT method are discussed by mean of numerical simulation.