Nuclear Fusion and Plasma Physics

Plasma equilibrium reconstruction of HL-2A tokamak

WANG Shuo, SONG Xian-ming, SONG Xiao, MAO Rui

2016, 36(3): 193-198. DOI: 10.16568/j.0254-6086.201603001

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The measuring accuracy of magnetic probes is greatly improved by eliminating the disturbance of TF coils through a new discharge scenario, together with a careful calibration process. The measuring accuracy of flux loop is also improved by removing the clamping diodes in integrator which cause the loss of fast information. With accurate magnetic field and flux information input, the iteration and fitting process of EFIT converges quickly and outputs reliable results, which are consistent with diagnostic results achieved by Langmuir probes, Hα array and CCD image. A new self-developed plasma equilibrium reconstruction code, called sFIT, is also introduced, which outputs the plasma shape information that agrees very well with that of EFIT.

Development of phase detector for LHCD system on HL-2A tokamak

CHEN Ya-li, LU Bo, LIANG Jun, ZENG Hao, BAI Xing-yu, WANG Chao, RAO Jun

2016, 36(3): 199-202. DOI: 10.16568/j.0254-6086.201603002

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Each channel of the phase measurement system was calibrated strictly by phase detector. And the curve of relationship between phase and voltage was obtained and linear fitted, with the linear fitting error of 3°. The expression of phase and voltage was obtained, which’s error is less than 0.7° compared with the calibrated curve. The phase measurement system was successfully used in the HL-2A lower hybrid waves experiment , four klystrons’s output phase was measured. And the phase fluctuation according to the cathode voltage during the experiment was obtained, with the conclusion that the cathode voltage change of 2.2% will due to the phase fluctuation of 13.8°.

Reverse shear discharge simulation of EAST tokamak

NIU Xing-ping1, ZHANG Shi-ding1, WU Bin2

2016, 36(3): 203-207. DOI: 10.16568/j.0254-6086.201603003

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Simulations of EAST reversed shear configuration are carried out using the TSC+LSC codes. The reversed shear plasmas are sustained by off-axis LHCD profiles. A series of simulations are performed to study the influence of the auxiliary heating applied time to plasma parameters. Based on these simulations, a novel control scheme was proposed and tested for control of the safety factor profile which is very useful in real time profile control in tokamak experiments.

Effects of toroidal rotation on the zonal flows at isentropic equilibrium in tokamak plasmas

XIE Bao-yi1, YU Jun1, GONG Xue-yu1, 2, CHEN You1, YU Jiang-mei1

2016, 36(3): 208-212. DOI: 10.16568/j.0254-6086.201603004

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The dispersion relation of the zonal flows in the tokamak plasma with toroidal rotation is derived by using the fluid model under the condition of isentropic equilibrium. The effect of toroidal rotation on the frequencies, pressure and density perturbations of the geodesic acoustic modes, low frequency zonal flows and sound wave modes are theoretically investigated, respectively. The results show that the toroidal rotation has no effect on the frequency of low frequency zonal flows, but can increase the frequency of geodesic acoustic modes gradually. In addition, it is found that the low frequency zonal flows possess the pressure and density disturbance in the form of a standing wave, and the geodesic acoustic modes and sound wave modes can propagate in the poloidal direction in the presence of toroidal rotation. And it is also found that the isentropic equilibrium can be considered as a special case of isothermal equilibrium.

Preliminary LOFA and In-vessel LOCA Analysis for CN HCCB TBS

WANG Yan-ling, ZHANG Long, WU Xing-hua, ZHAO Zhou

2016, 36(3): 213-218. DOI: 10.16568/j.0254-6086.201603005

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The RELAP5 model was recreated according to the latest design of the CN HCCB TBS, and two design basis accidents, in-vessel loss of coolant accident (LOCA) and loss of flow accident (LOFA), were investigated. According to the results, the safety of CN HCCB TBS is guaranteed during the two accident situations, and the thermal-hydraulic transient analysis can give the information about the TBM safety relevant behavior in accidents, suggesting the necessary protection system and their responding time.

Hydraulic analysis for TBM first wall based on CFD method

ZHOU Bing, ZHAO Zhou, WU Xing-hua

2016, 36(3): 219-223. DOI: 10.16568/j.0254-6086.201603006

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Based on the computational fluid dynamics (CFD) methods and combined with the first whole test blanket module system in the world, the thermo-hydraulic analysis for the first wall and the connecting ribs was performed. It includes the analyses of pressure, flow velocity, flow distribution and heat transfer coefficients. The analysis results are given. Finally, the heat transfer coefficients obtained by CFD are compared with the results calculated by Gnilinski analytical formula, and both are well agreeable.

Eletromagnetic shielding optimization of ECE imaging diagnostic on EAST tokamak

TONG Li, ZHAO Zhen-ling, CHEN Dong-xu, ZHU Yi-lun, HAN Dong-qi, XIE Jin-lin

2016, 36(3): 224-230. DOI: 10.16568/j.0254-6086.201603007

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Electron cyclotron emission imaging (ECEI) diagnostic system with 384 channels was installed on EAST tokamak. Since EAST was equipped with 4MW ICRF system, 4MW LHCD system and NBI system, the ECEI diagnostic system on EAST was heavily interfered, especially by the lower hybrid wave. The optimization of the electromagnetic shielding is presented, which help to reduce the interference to 40dB. Appropriate copper mesh shield and the correct ground connection are the key solutions. The comparisons of the ECEI raw signals before and after the optimization clearly show that the shielding performance is greatly improved.

Design of antenna temperature measurement for EAST 6MW/4.6GHz LHCD system

WU Ze-ge1, YANG Yong1 QI Tuan-jie2, LIU Liang1, WANG Mao1, WANG Ping1, YANG Fei1

2016, 36(3): 231-236. DOI: 10.16568/j.0254-6086.201603008

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In order to protect the LHW antenna, it is necessary to measure the antenna temperature. According to the antenna specifications, the K type thermocouple is selected as the measurement tool. The signals generated by 8 thermocouples are acquired by a temperature logging device with high speed, and the measurement data are read remotely by software for display. Fiber communication is adopted to resist the EMI brought by tokamak in the loop of measurement hardware. The test results show that this method is able to real time reflect the trend of antenna temperature accurately, which lays a foundation for further antenna thermal protection.

Inconel 625 material property for HL-2M vacuum vessel

HUANG Yun-cong, RAN Hong, CAO Zeng, HUO Ji-lai, SONG Bin-bin

2016, 36(3): 237-242. DOI: 10.16568/j.0254-6086.201603009

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The main material of HL-2M vacuum vessel is determined as Inconel 625. Through the comparative study of three original base metal and welded joints, it is obtained that the comprehensive performance of the imported material has more advantage than others. And these different material property data is crucial to the manufacture process of HL-2M vacuum vessel.

Design and analysis of electrical parameters of large area NBI RF ion source

CHEN Yu-qian, XIE Ya-hong, HU Chun-dong, JIANG Cai-chao, CUI Qing-long

2016, 36(3): 243-246. DOI: 10.16568/j.0254-6086.201603010

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To explore the influence of the RF ion source driver coil electric parameters on the RF discharge, the physical analysis of RF ion source plasma excitation was carried out, and the relationship between the frequency selection of RF power source and coil discharge current, coil voltage and discharge pressure was studied. The main parameters of RF ion source driver was designed, the RF ion source driver device is developed. The last device obtained successfully hydrogen plasma RF discharge. The experimental results and theoretical calculation results accord with well.

Thermo-technical performance optimization on first wall in fusion reactor applied with continuous W/Cu functionally graded material

ZHAO Yong-qiang1, HUANG Sheng-hong1, WANG Wei-hua2

2016, 36(3): 247-253. DOI: 10.16568/j.0254-6086.201603011

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The thermo-technical performance optimization on first wall in fusion reactor made by such continuous W/Cu graded material with different composition distribution parameter p was descrided The thermal/mechanical responses of the first wall mockup under steady-state heat loads of 8MW•m⁻² and heat shock loads of 1GW•m⁻² during plasma disruptions are computed numerically with the finite element method. Under the same steady heat load conditions, the optimized composition distribution parameter p for composition continuous W/Cu graded material is very different with that of previous quasi-continuous W/Cu graded material. A 26% reducing in thermal stress is observed for first wall with composition continuous W/Cu graded material, demonstrating a more excellent performance. In the process of heat shock, the damage degree measured by volume fraction of plastic deformation is changing with different composition distribution parameter p, its optimized value is different with that obtained in steady state conditions. In consideration of environment conditions endured by first wall, the optimized value should be chosen to be close to 1.2. In general, there is a more prominent advantage for composition continuous W/Cu graded material applied in first wall design of fusion reactor due to its continuous variation of thermal physical properties and mechanical properties.

Design and flow characteristics research of test section for water-cooled solid blanket

LIAO Shi-liang, CAO Xue-wu

2016, 36(3): 254-259. DOI: 10.16568/j.0254-6086.201603012

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The scaling design of multi- parallels test section and flow distribution characteristics are studies based on the first wall of water-cooled solid blanket (WCSB) sub-module. Scaling analysis on the structure of first wall is carried out by utilizing scaling law to gain the parameters of test section. Using the method of computation fluid dynamics(CFD), numerical simulation is conducted based on the parameters of test section, and the flow characteristics are analyzed. The results are compared with that of the prototype to verify that the parameters of test section obtained by the scaling method CAD reflect effectively the flow characteristics of the first wall of WCSB sub-module. The research can provide reference for building experimental facility.

Establishment and analysis of survey reference network for KTX reversed field pinch device

FU Chen-shuo1, LIU Wan-dong1, YANG Qing-xi2, LI Hong1,XU Yong-xing3, GU Yong-qi2, ZHANG Ping2

2016, 36(3): 260-265. DOI: 10.16568/j.0254-6086.201603013

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The main components of the Keda torus experiment(KTX) device, the requirements of the installation, and the assembly scheme are described. With the survey reference networks and the coordinate control network, the assembly position and accurate measurement of the KTX components was ensured.

Monte Carlo simulation for uncertainty evaluation of helium mass spectrometer leak detection

YANG Dan1, 2, CHEN Chang-qi1, QIU Shi2

2016, 36(3): 266-270. DOI: 10.16568/j.0254-6086.201603014

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A new method for evaluating uncertainty of the results of helium mass spectrometer leak detection is presented. Based on Monte Carlo method, the evaluative model is developed for simulating random detection data to obtain the random samples to calculate the uncertainty of detection result. The uncertainty is analyzed and compared with the uncertainty by traditional method. This indicates that the uncertainties conformity between traditional method and Monte Carlo method which is effective to evaluate uncertainty of the results of helium mass spectrometer leak detection. What’s more, the calculation is more efficiency and application is more comprehensive.

Purification and on-line monitoring systemin liquid lithium loop

XUE Xiao-yan1, ZHANG Wei-wei1, ZUO Hao-yi1，OU Wei2,CAO Xiao-gang2, YANG Dang-xiao1,CHEN Shun-li2, GOU Fu-jun2

2016, 36(3): 271-275. DOI: 10.16568/j.0254-6086.201603015

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The purification and on-line monitoring system in the liquid lithium loop was introduced. By using the cold trap and the thermal trap, the facility can reduce C, O, N and hydrogen isotopes concentrations below 10wppm. At present, the resistance curves as a function of temperature with and without lithium have been measured by the four electrode method measuring the resistance, and the resistivity of pure liquid lithium as a function of temperature has been derived by the polynomial fitting and calculation.

Measurement of ion velocity distribution in plasma jet with dielectric barrier geometry at atmospheric pressure

XIONG Li1, QI Bing2

2016, 36(3): 276-281. DOI: 10.16568/j.0254-6086.201603016

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A new method based on fast Fourier transform, is presented to calculate ion velocity distribution by analyzing electromagnetic radiation signal from atmospheric nonequilibrium plasma. This method is based on a dipole model. Results show that the ion velocity distribution deviates from Maxwell distribution over time. The ion velocity and relative ion number fluctuate regularly with time.

Numerical simulation and experiment of plasma torch for LILW vitrification

CHEN Ming-zhou, HUANG Wen-you, Lü Yong-hong, LIU Xia-jie, BAI Bing

2016, 36(3): 282-288. DOI: 10.16568/j.0254-6086.201603017

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In order to examine a high power non-transferred type arc plasma torch used for vitrification of low and intermediate level radioactive waste (LILW) vitrification, numerical simulation and experiments verification were carried out. Temperature field was obtained based on simulation of a 3D model of the plasma torch. According to the simulation results, the highest temperature of the plasma, up to 1.77×10⁴ K, was in the channel of the first anode. The calculated values of the arc voltage were higher than the experimental ones, and the difference decreased with the increase of arc current. Tests with simulated waste established that the distance from the nozzle of the plasma torch to the waste was suitable for vitrification process. The results show the 3D numerical modelling provides valuable engineering information for plasma melter design. And the simulation results can be used as the input data for understanding and describing the temperature and velocity fields as well as the physic-chemical process in the plasma melter.

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