Table of Content

15 March 2017, Volume 37 Issue 1

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Plasma Physics

Design and application of a data analysis code for plasma turbulence

SHEN Yong1, DONG Jia-qi1, 2, SHI Zhong-bing1, ZHAO Kai-jun1

2017, 37(1):  1-7.  DOI: 10.16568/j.0254-6086.201701001

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An analyzing method to deal with turbulence data is proposed. Based on this method, a turbulence data analysis code is developed whose function is to study the energy transfer in plasma turbulence. The algorithm is introduced and the code test is made. The code was used to investigate the turbulence data from a Reversed-field-pinch (RFP) experiment and then the intrinsic excitation and increment mechanisms of the edge turbulence of magnetic controlled fusion plasmas are revealed.

Effects of toroidal rotation on geodesic acoustic mode on tokamak plasmas

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

2017, 37(1):  8-13.  DOI: 10.16568/j.0254-6086.201701002

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With the dispersion relation derived from the gyrokinetic equation with the plasma equilibrium toroidal rotation, the frequencies and damping rates of the geodesic acoustic modes, low frequency modes and sound wave branch are investigated, respectively. The results show that the frequency of the geodesic acoustic mode could increase with the toroidal rotation Mach number, while the collisionless damping rate will decrease with the toroidal rotation Mach number rapidly. In addition, the frequencies and damping rates of the low frequency modes and sound wave branches will decrease with the toroidal rotation Mach number, and the influence of the toroidal rotation on the sound wave branches frequencies and damping rates are very small and can be neglected.

Development of quartz crystal microbalance deposition diagnostic system for HL-2A divertor

WU Ting, CAI Lai-zhong, ZENG Xiao-xiao

2017, 37(1):  14-18.  DOI: 10.16568/j.0254-6086.201701003

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In order to measure the deposition in the remote area behind the divertor of a tokamak due to plasma wall interactions (PWI) and get a better understanding of PWI process in this remote area in real time, the first quartz crystal microbalance (QCM) deposition diagnostic system for the HL-2A divertor was developed. After the preliminary test, it was found that the average sampling rate is about 13~14s^-1 and its frequency resolution is 0.01Hz. The resonant frequency shift of the crystal is proportional to the mass change deposited in the surface of the crystal, which coincides with conclusion from the famous Sauerbrey equation. The average deposition rate is about 2.0ng•s^-1, which means it is capable to measure nanogram quality. These results show that this QCM deposition system is reliable and effective.

Analysis of vertical instability on HL-2M tokamak

LI Bo, SONG Xian-ming, LI Jia-xian, SONG Xiao

2017, 37(1):  19-24.  DOI: 10.16568/j.0254-6086.201701004

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Control problem of vertical instability of HL-2M tokamak was studied with DⅢ-D TokSys. The vertical displacement event (VDE) was controlled by the vessel and active conductors, the study of the eigenmodes and current distribution of the vessel greatly reduced the difficulty of modeling, and a mathematical model was set up and parameters of active conductors and the power supply were verified. The growth rates and maximum controllable vertical displacement for different plasma shape configurations with different elongation were calculated. Simulations for snow flake, single null and double null divertors were made in simulink environment by TokSys with a PD controller. Results show that VDE can be controlled very well for different plasma shape configurations.

Optimization and analysis of helium-cooled divertor cooling fingers

JIN Yu-zhong1, LIU Xiang1, CHEN Lei1, LIAN You-yun1, WANG Zheng-yu2

2017, 37(1):  25-31.  DOI: 10.16568/j.0254-6086.201701005

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A HEMJ unit (He-cooled divertor with multiple-jet cooling) is simulated and analyzed by ANSYS/CFX under the same heat load but different cooling conditions. Temperature and surface convective heat-transfer coefficient field was obtained and is taken as the loading conditions for thermal mechanical analysis. Thermal mechanical analysis is performed by ANSYS/Mechanical under steady-state conditions for HEMJ units. Stress distributions of divertor structures with different structural parameters were achieved. And the influence of the changeable structural parameters on thermal stress is analyzed and filtered to acquire a design with lower thermal stress than the orignal one. And finally an optimal design was obtained.

Simulation and experimental research of shell forming of future fusion engineering test reactor vacuum vessel

FAN Xiao-song, WU Jie-feng, LIU Zhi-hong

2017, 37(1):  32-36.  DOI: 10.16568/j.0254-6086.201701006

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Simulation of the vacuum vessel’s shell for the fusion rector is executed to analyze the thickness reduction, springback and residual stress of the formed workpiece based on the forming process of ITER. Results of forming experiment are compared with that of simulation to inspect and demonstrate the effectiveness of numerical simulations.

Study on diagnosis of pulsed laser induced photo-detachment technique for capacitively coupled negative O2 plasma

WANG Tao, WANG Jun, TANG Cheng-shuang, YANG Yu, XIN Yu

2017, 37(1):  37-42.  DOI: 10.16568/j.0254-6086.201701007

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A high energy pulsed laser beam with wavelength of 532nm was applied to irradiate the capacitively coupled O2 plasma driven by 40.68MHz. Spatial potential of the plasma and electro negativity are diagnosed by exerting a certain positive bias on the probe aligned with laser beam at the center. The experimental results show that a transition of signal wave shape on the probe occurs from V-shaped to invert U-shaped as increasing positive bias. The transition voltage point is just the spatial potential of electronegative plasma. An empirical method was given to obtain the spatial potential of negative plasma by using LIPD technique. Additionally, plasma electro negativity keeps a constant basically as increasing positive bias beyond the plasma spatial potential. The experiments still show a trend of decrease in electro negativity of O2 plasma with increasing RF input power.

Nuclear Fusion Engineering and Technology

Selection and fabrication of conductor materials for HL-2M toroidal field coils

QIU Yin, LI Guang-sheng, ZOU Hui, SHAN Ya-nong,CAI Li-jun, LIU Jian, YANG Qing-wei

2017, 37(1):  43-47.  DOI: 10.16568/j.0254-6086.201701008

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The demountable toroidal field coils (TFC) structure was adopted in order to assemble the vacuum vessel chamber and poloidal field coil (PFC) integrally in HL-2M tokamak. Copper alloy selection for TFC is a compromise between conflicting requirements for high fatigue strength and high electrical conductivity. After several stress analyses, three copper alloys were used in different parts of TFC. Adopting vacuum casting and forging manufacturing technology, large size and special shape copper alloy plates were fabricated. Under tests, the properties of copper alloy plate meet the requirements of TFC.

Estimation of magnetic force exerted on shield in gradient DC magnetic field

XIA Zhi-wei, LI Wei, LI Bo

2017, 37(1):  48-51.  DOI: 10.16568/j.0254-6086.201701009

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In the gradient DC magnetic field, the order of the magnetic force for the shield made from soft magnetic material was estimated. The magnetic force on a cuboid shield made from pure iron was studied by the finite element analysis (FEA) and experimental test. The preliminary results show that for a cuboid shield with inner dimension of 100mm×100mm×150mm and thickness of 20mm, placed within a DC magnetic field of about 0.2 T with average gradient 0.03T?m?1, its magnetic force is about 184N, close to its own gravity force. The analysis and test results show the magnetic force increases together with the field strength. The analysis results deviate from the experiment by about 21% under 0.2T field. Therefore, considering proper margins, FEA is an effective and reliable method to estimate the magnetic force exerted on shield by a gradient DC field.

Effects of wettability and magnetic field on the liquid metal free surface film flow state

ZHANG Xiu-jie, PAN Chuan-jie, XU Zeng-yu

2017, 37(1):  52-57.  DOI: 10.16568/j.0254-6086.201701010

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The study of the effects of wettability and magnetic field on the liquid metal free surface film flow state is performed by numerical simulation and experiment. Firstly the effects of wettability on the film flow state are investigated by numerical simulations. The results show that the liquid metal film is easy to become rivulet flow and cannot cover the whole bottom surface when the wettability is poor, the rivulet flow is easily developed when the initial film thickness is small, it is more easily developed into rivulet when the destiny becomes smaller as the initial film thickness and other conditions are same. Secondly, the effects of magnetic field on the film flow are studied, it is indicated that the cover bottom surface of liquid metal film under the condition of strong magnetic field increases compared with the condition of no magnetic field when the wettability of liquid to channel is poor, and the strong magnetic field can suppress the turbulence of the film flow. In the end, the experimental results of the liquid metal film flow show that the film flow of GaInSn alloy is easily contracted into rivulet flow, which is coincident with the numerical results. Above results are valuable for the design of liquid first wall of magnetic fusion reactor.

Thermal-hydraulic computation and analysis for helium cooling ceramic blanket of HCCB-DEMO

WANG Su-hao1, 2, CAO Qi-xiang2, WU Xing-hua2, WANG Xiao-yu2, ZHANG Guo-shu2, FENG Kai-ming1, 2

2017, 37(1):  58-63.  DOI: 10.16568/j.0254-6086.201701011

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With the development of HCCB-DEMO blanket technology, an updated conceptual design of helium cooled blanket with ceramic breeder was proposed. Based on 3D FEM software ANSYS CFX，thermal-hydraulic analysis including first wall model, breeder unit model, stiffen grid model and integration model for HCCB blanket is presented in this paper. The results demonstrate that the maximum temperature of each material is in design limits; inlet/outlet temperature of coolant is 300/500°C under the independent analysis of sub-components, which indicate that the design requirements are satisfied. Comparing with three independent analysis models, the integration results showed that the thermal interaction between first wall and Be pebble bed have important influence; the maximum temperature of Be pebble bed exceeded the design limits. A series of optimization design for HCCB blanket focused on these problems would be the next step.

Neutronics simulation of water cooled breeder blanket

LIU Chen, CAO Xue-wu

2017, 37(1):  64-68.  DOI: 10.16568/j.0254-6086.201701012

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The simulation results from the FENDL2.1, FENDL3.0 and JEFF3.2 with the Li sphere shell model were compared. Simulations of the water could breeder blanket are carried out with the neutronics 1D model and the 3D neutronics model, respectively. The results show: the FENDL3.0 is the selected data libraries for 3D neutronics simulation of blanket module; the cylinder shell model is the first consideration for 1D neutronics simulation of WCBB; the TBR of the 3D blanket neutronics model can satisfy the demand of tritium self-sustaining. The out board blanket makes major contribution to the TBR.

Optimization of EAST ICRH antenna Faraday shield cooled structure

DU Qun-shan1,2, YANG Qing-xi1, WANG Yong-sheng1, GE Jian1, YUAN Shuai1,ZHANG Xin-jun1, QIN Cheng-ming1, ZHAO Yan-ping1

2017, 37(1):  69-74.  DOI: 10.16568/j.0254-6086.201701013

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In order to meet the requirement of long pulse and steady-state operation of EAST in future, the existing cooling structure of Faraday shield (FS) needs to be optimized. Through theoretical and numerical simulation method, the optimized design of original FS cooled structure is achieved, as well as the distributions of velocity and pressure of improved FS cooled tube are obtained. By comparing the fluid pressure drop and structural temperature distributions of FS under different inlet conditions, the adaptive operational flow parameters for optimized FS structure are obtained, which provide theoretical guidance for future operation of ICRH antenna FS.

Design of servo control system for EAST articulated maintenance arm

ZHANG Jun1, CHENG Yong1, XI Wei-bin1, FENG Hans-heng1,PAN Hong-tao1, XU Jie1, TAO Zi-hang2

2017, 37(1):  75-80.  DOI: 10.16568/j.0254-6086.201701014

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Working at the special EAST articulated maintenance arm (EAMA) operating environment, a servo control system is designed and implemented in this paper. The system adopts a new solution of servo system based on the distributed control structure. The high performance PIC microcontroller is used for the hardware circuit design in control strategy, and the speed and position closed-loop control algorithm is applied to realize the high precision position control. Finally, the experiments show that the servo control system for EAMA can meet the operation requirements, and has good dynamic and static performance.

Conceptual design and analysis of diverter target in CFETR

LIU Xiu1, CAO Lie2, LI Lei2, XU Tie-jun2, YAO Da-mao2

2017, 37(1):  81-86.  DOI: 10.16568/j.0254-6086.201701015

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Based on previous research the conceptual design of the divertor target of The China fusion engineering testing reactor (CFETR) is presented. The thermal, mechanical analyses on the basis of worst case load show that the temperature and stresses are within the allowable limits, which validate the reliability of the model. The conceptual design and analyses can offer reference basis for the future engineering design.

Preliminary design and neutronics analysis of CFETR WCCB experimental mock-up

GAO Fang-fang1, 2, ZHANG Xiao-kang2, ZHU Qing-jun2, HUANG Kai2, LIU Song-lin2

2017, 37(1):  87-93.  DOI: 10.16568/j.0254-6086.201701016

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Based on the water cooled ceramic breeding blanket (WCCB) basic scheme for CFETR, preliminary design and neutronics analysis for experimental mock-up was performed. The experimental mock-up consists of three tritium breeder zones, two neutron multiplying zones and three cooling plates, first wall, tungsten armor and back plate. In the design, the local tritium production rates (TPR) from 6Li and 7Li in breeder zones were measured with Li2CO3 pellet. The neutronics analysis of experimental mock-up was evaluated by MCNP code with the IAEA Fusion Evaluated Nuclear Data Library FENDL2.1, the neutron energy spectra and TPR values of each region were obtained. The distribution of neutron flux and the neutron spectra in each region indicated the edge effect of the experimental mock-up is important, and the neutron spectrum in the central region is the most representative of the neutron energy spectrum of the original blanket. The reflector can elevate the TPR value. By considering the energy spectrum, TPR and the economic factors, the reflector with steel is a better candidate.

Activation calculation and analysis for CFETR blanket

JIANG Shuai, CHEN Zhi, XU Xie

2017, 37(1):  94-98.  DOI: 10.16568/j.0254-6086.201701017

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Using Monte Carlo code MCNPX and the activation calculation code FISPACT-2007, nuclear heat, radioactivity and shutdown dose rate for China fusion engineering test reactor (CFETR) were calculated. The calculation results show that the total radioactivity is 2.34-10¹⁹Bq at shutdown after one year operation and the total radioactivity is 7.98-10¹⁸Bq after ten years which is 12.1% of the original radioactivity. The results show that there isn’t serious environmental issue.

Design of the molten salt blanket and the calculation of tritium breeding ratio

YIN Miao1, SONG Yun-tao2, LEI Ming-zhun2, XU Kun1

2017, 37(1):  99-104.  DOI: 10.16568/j.0254-6086.201701018

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To confirm the appropriate material, certain division and the corresponding thickness of model for the blanket design of fusion reactor, the tritium breeding ratio calculation and analysis in one-dimensional and three-dimensional model are presented. An appropriate molten salt design blanket that contents the tritium self-sustaining (TBR=1.3162) is found.

Integration of real-time GPU parallel equilibrium reconstruction in EAST plasma control system

PEI Xiao-fang, YUAN Qi-ping, HUANG Yao, LUO Zheng-ping, XIAO Bing-jia

2017, 37(1):  105-112.  DOI: 10.16568/j.0254-6086.201701019

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In order to improve the accuracy and efficiency of plasma real time equilibrium reconstruction, a faster parallel code named P-EFIT has taken the place of RT-EFIT. After briefly outlining the hardware and software architecture of the EAST PCS, the integration of the parallel plasma equilibrium reconstruction code P-EFIT into EAST PCS is described. Benchmark tests are carried out to verify the integrated system's correctness using history experimental data. P-EFIT was applied for plasma shape control in EAST operation campaign and the control performance is satisfied.

Non-Fusion Plasma Applications

Influence of cylindrical discharge plasma array on transmission attenuation of 2~18GHz TM electromagnetic wave

LIU Yang, SHI Jia-ming, WANG Jia-chun, WANG Qi-chao

2017, 37(1):  113-117.  DOI: 10.16568/j.0254-6086.201701020

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Influence of the cylindrical discharge plasma array on transmission attenuation of 2~18GHz TM electromagnetic wave was experimentally studied from the discharge unit numbers, the discharge unit distribution and the discharge voltage by the experimental measurement system. The results show that the transmission attenuation effect of the plasma on the incident electromagnetic wave in 10~18GHz can be improved by reducing the number of discharge units. In 2~18GHz, a proper distance between plasma discharge units can also do good for the attenuation performance. Increasing the discharge voltage is favorable for increasing the attenuation degree and expanding the range of the attenuation bandwidth.

Spectrum analysis and surface inactivation of E. coli bacteria by atmospheric pressure N2/O2 plasma jet

FAN Ming-yang，HAO Xiao-long

2017, 37(1):  118-124.  DOI: 10.16568/j.0254-6086.201701021

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The sterilization effects of surface E. coli bacteria by N2/O2 source atmospheric pressure plasma jet (APPJ) were studied, and the spectroscopic properties of nitrogen/oxygen source atmospheric pressure plasma jet were analyzed. Experimental results showed that under discharge voltage at 6.8 kV, gas flow rate at 4L?min?1 and treatment time at 3min, E. coli bacteria inactivation rate of APPJ with N2/O2 at 1:4 reached 98.4%, close to that of oxygen source APPJ. Active substances of nitrogen/oxygen source plasma jet were analyzed by optical emission spectroscopy (OES) to interpret the mechanism of the microorganism of E. coli bacteria, and it was considered that active substances, such as NO?γ, OI, ?OH, played the important roles in the surface E. coli bacteria inactivation process. This would provide the experimental basis and technical support of application researches of atmospheric pressure N2/O2 plasma jet, such as environmental hygiene, microbial inactivation and so on.