Nuclear Fusion and Plasma Physics

Electromagnetic calculation and load analysis of the HL-2M TF coils

YUAN Bao-shan, LONG Yong-xin, QIU Yin, LI Guang-sheng, LIU Jian, ZHOU Hui, SHAN Ya-nong

2017, 37(3): 249-256. DOI: 10.16568/j.0254-6086.201703001

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Bitter plate structure was adopted for the toroidal field (TF) coils of the building HL-2M tokamak. The electromagnetic field and its ripple of TF coils were calculated by the closed polygon filament current model, the electromagnetic force caused by the TF coil current and the overturning moment produced by TF coil currents and PF were also computed. The results have definite reference significance for the design of the TF coils.

Numerical simulation of nonlinear evolution of double tearing mode based on finite volume method

LEI Xiao-chen, LI Xin-xia, MA Jun, GONG Xue-yu

2017, 37(3): 257-261. DOI: 10.16568/j.0254-6086.201703002

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Starting from the theory of magnetic fluid, a flux difference splitting numerical scheme based on ?nite volume method is used to solve the resistive magnetic fluid equations with hyperbolic conservation laws. The C++ code is developed to simulate the long time nonlinear evolution of the double tearing mode in plane geometry, several typical stages of magnetic reconnection in the nonlinear development of double tearing mode are clearly observed. In addition, the effect of changing the resistivity size and the distance between the two rational surfaces on the instability of the double tearing mode was discussed. A feasible and high accurate numerical algorithm for the study of magnetic fluid dynamics was provided.

Application of high-speed CCD diagnostic system in studying boundary plasma on HT-7 tokamak

LI Feng-juan, ZHU Xiang, YANG Jian-hua, GAO Xiang

2017, 37(3): 262-266. DOI: 10.16568/j.0254-6086.201703003

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On the HT-7 tokamak, a high-speed CCD diagnostic system was set up, the visible radiation of boundary plasma was measured. During the experiments on the HT-7 tokamak, a poloidal rotating visible radiation belt in the plasma boundary region was observed for the first time, the frequency calculated by CCD system is 858Hz and the value is 952Hz by the calculation of multi-channel H_α array measurement. According to the multi-channel magnetic probe signals, there was a m/n=3/1 mode within the plasma and its frequency is 972Hz. The magnetic island width is about 2.5cm based on the Te profile measured by ECE system.

Characteristics of helium plasma produced in cascade arc discharge

MA Xiao-chun, CAO Xiao-gang, CAO Zhi, HAN Lei, XIA Wen-xing, SHU Lei, HE Ping-ni, GUO Fu-jun

2017, 37(3): 267-273. DOI: 10.16568/j.0254-6086.201703004

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The basic characteristics of helium plasma, produced in a single cathode arc discharge device with cascade bias voltages applied, were studied. Helium axial transport was described and compared with optical spectrum data. Experimental results show that the electron temperature and electron density of the helium plasma increases with discharge current and the magnetic field. The emission spectrum variation of helium atom and ion with discharge current, bias and magnetic field, was measured and analyzed. Finally the integral radiation effect on tungsten specimen surface bombarded by helium ions was observed. Results not only show the basic characteristics of helium plasma, but for assessment of damage resulted from helium plasma interaction with tungsten, such as bubbles, swelling and embrittlement etc., have important reference value if joint neutron reaction (n, α) exists in the future reactor.

2D/3D electromagnetic analysis for CFETR vacuum vessel

YAO Yao, LU Kun, GE Jian, NI Xiao-jun

2017, 37(3): 274-278. DOI: 10.16568/j.0254-6086.201703005

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The 2D/3D electromagnetic analyses based on ANSYS were carried out for simplified CFETR vacuum vessel. The distributions of magnetic field and electromagnetic force in vacuum vessel were obtained. The results show that the distributions of magnetic field and electromagnetic force in 2D/3D vacuum vessels are nearly consistent. The results indicate that the 3D ANSYS model can be replaced by 2D ANSYS model for electromagnetic analyses for future simplified vacuum vessels.

Transition properties of Be-like Kα X-ray from ArⅩⅤ

LI Wen-yi, HU Feng, SANG Cui-cui, SUN Yan, MEI Mao-fei, YANG Jia-min

2017, 37(3): 279-284. DOI: 10.16568/j.0254-6086.201703006

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Calculations of energy levels and radiative rates for Kα transitions among the lowest 40 fine-structure levels were introduced in Be-like ArⅩⅤ. The wavelengths, oscillator strengths, radiative rates and lifetimes for all possible Kα transitions have been calculated using the multi-configuration Dirac-Fock method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. These results can be used to analysis the previous experimental results and guide the design of the future experiments.

Fabrication of large cross-section copper conductor for HL-2M poloidal field coils

QIU Yin, LI Guang-sheng, ZHOU Hui, QIAN Qiao-li, SHAN Y-nong, YANG Qing-wei

2017, 37(3): 285-289. DOI: 10.16568/j.0254-6086.201703007

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The specifications of the large square cross-section copper conductor used in poloidal field coils (PFCs) for HL-2M, cold rolling technology with pilger mill and more testing were described. Adopting this technology, large cross-section copper tube with cooling was fabricated. The testing results show the size and properties of the copper tube fabricated by this technology meet the requirements of PFC.

Design of fasteners for HL-2M TF coils

ZHOU Hui, LI Guang-sheng, CAI Li-jun, QIU Yin, SHAN Ya-nong

2017, 37(3): 290-296. DOI: 10.16568/j.0254-6086.201703008

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The structure forms of fasteners for HL-2M TF coils are designed according to their function and the mechanical requirements. The proper materials are applied to all the units of the fasteners. The structure details of the female/male bushings of the expanding pins are analyzed and discussed. The validation of the performance of the expanding pins is implemented by experiments.

Thermal hydraulics design and analysis for ITER shield block vacuum hot helium leakagedetection equipment

LENG Zhen, KANG Wei-shan, CHEN Ji-ming

2017, 37(3): 297-301. DOI: 10.16568/j.0254-6086.201703009

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Thermal hydraulic analysis and design for the ITER shield block vacuum hot helium leakage detection equipment was done to get the best heating scheme, and the result implied that the heating process would not show any unpredictable structure damage, moreover, the shield block could be heated efficiently, and both the engineering requirement and the thermal stress of components technical requirement could be satisfied by means of changing inlet gas temperature in stages.

Failure analysis of Be/Cu joint in ITER first wall mock-ups

LIU Dan-hua, WANG Ping-huai, LI Qian, YANG Bo, JIN Fan-ya, CHEN Ji-ming, ITER Ping-Bi-Bao-Ceng-Zu

2017, 37(3): 302-307. DOI: 10.16568/j.0254-6086.201703010

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ITER first wall mock-ups were fabricated by joining CuCrZr and 316L(N) stainless steel with explosion welding, machining cooling channel, and then bonding Be tiles on CuCrZr interface with a hot isostatic pressing (HIP) technology, but a few large scale defects on the Be/Cu joint interface were observed by ultrasonic testing. In order to guarantee the mock-up quality, destructive tests were performed on these failed mock-ups. Samples were observed with optical microscope and SEM, and the possible cause of the defects formation was identified preliminarily.

Thermo-mechanical response simulation and analysis of W material under fusion related transient heat flux

LI Xiang-bin, LI Chang-jun, ZHU Da-huan, CHEN Jun-ling

2017, 37(3): 308-312. DOI: 10.16568/j.0254-6086.201703011

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Thermo-mechanical analysis was performed to simulate the temperature and stress distribution for tungsten material facing plasma under fusion related transient heat flux loading and unloading using finite-element analysis code ANSYS. And combined its mechanical properties, its crack behavior under transient heat flux was analyzed. The results show that the crack thresholds of W are about 200MW•m^–2(~5ms), 460MW•m^–2 (~1ms) and 660 MW•m^–2(~0.5ms) under single heat shot, corresponding to the coincident heat flux factors (14.14~14.75 MW•m^–2•s^1/2).

Preliminary experimental study of NB counter-injection on EAST

LIU Cheng-yue, CHEN Mei-xia, WU Bin

2017, 37(3): 313-318. DOI: 10.16568/j.0254-6086.201703012

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The experiments about plasma heating and current drive with NB counter-injection on EAST are presented and the energy heat transport in the neutral-beam injection with high power is also analyzed with the TRANSP code developed by the Princeton Plasma Physics Laboratory. The experiments and simulations show that neutral beam injection can effectively increase background plasma temperature, lead to beam driven non-inductive current, enhance plasma rotation and effectively improve plasma confinement.

Establishment and verification of magnetic field model for EAST vacuum chamber

XU Gao-bin, LI Kun, WANG Yue-ying, MA Yuan-ming, CHEN Xin, SHEN Biao

2017, 37(3): 319-324. DOI: 10.16568/j.0254-6086.201703013

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Based on Biot-Savart law, through learning the internal EAST plasma current state of motion, establishing the mathematical model of magnetic field inside EAST, simulating and analyzing the experimental data by Matlab, the model is analyzed and verified. Through error analysis, the model is improved, and studies show that improved model fit well with the experimental data, the error is small. Meanwhile related research and conclusions have some significance for measuring the magnetic field of tokamak vacuum chamber, it provides the theoretical basis for MEMS magnetic sensor on electromagnetic measurement system of superconducting tokamak.

New structural design of heat-sink cooling water transition joint for EAST tokamak

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

2017, 37(3): 325-330. DOI: 10.16568/j.0254-6086.201703014

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For cooling water transition joints used in EAST divertor heat-sink in the process of plasma disruption its main electromagnetic load was analyzed and calculated, a new transition joint structure were put forward. Through finite element analysis of the new structure under the extreme load, pre-research and test of welding, the joint structure and the fabrication scheme were optimized, finally the cooling water transition joints design used in divertor heat-sink was accomplished, and successfully applied to the upgrade of EAST divertor heat-sink.

Exploration of voltage mode of the new fast control power supply for EAST

HUANG Hai-hong, BI Nan-xia, YU Jia, WANG Hai-xin

2017, 37(3): 331-335. DOI: 10.16568/j.0254-6086.201703015

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Aiming at the requirements of large current and fast response for the fast control power supply for EAST, the second generation supply could apply voltage control mode to achieve the maximum of current rising rate, while active feedback power of plasma’s vertical displacement retained current control mode, which was used in the first generation of fast control power supply for EAST. To solve the problem of overvoltage protection caused directly by the reverse energy produced by the frequent overcurrent protection when the power supply outputs high voltage, current limiting protection was applied. Experimental results prove that voltage mode can greatly improve the ability of power supply to restrain plasma's vertical unstable displacement.

Corrosion behavior of 316L stainless steel in stagnating liquid lithium

SHU Lei, CAO Zhi, XIA Wen-xing, CAO Xiao-gang, HE Ping-ni, WEI Jian-jun, Gou Fu-jun, YANG Bin

2017, 37(3): 336-341. DOI: 10.16568/j.0254-6086.201703016

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The corrosion behavior of 316L stainless steel in stagnating liquid lithium at 350℃ for 500h was investigated by self-designed Laser-Induced Breakdown Spectroscopy(LIBS) analysis equipment, SEM, EDX and Vickers hardness. Microstructure analysis shows that the intergranular corrosion of base metal area is obvious, and the thickness of corrosion layer is about 2.7μm. The hardness of corrosion base material surface is approximately HV234.72, which is approximately 0.78 times lower than that before corroded. LIBS analysis indicated the loss of Ni or Cr occurred in the sample during lithium corrosion, the quantity of lithium element in the corroded zone decreased with depth increasing in the sample, however, the circumstances were reverse for the nickel and chromium element. And penetration depth of liquid lithium in base metal of 316L S.S is approximately 3.5μm, which is approximately 0.6 times lower than that weld zone.

Influence of post-weld heat treatment on the 316LN welded joints for nuclear fusion

LIU Li-ping, YE Ming-you, WU Jie-feng, WEI Jing, XIN Ji-jun, SHEN Xu

2017, 37(3): 342-345. DOI: 10.16568/j.0254-6086.201703017

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In order to study the post weld heat treatment (PWHT) of the austenitic stainless steel 316LN, the effects on the microstructure and mechanical properties in TIG welded joints of 316LN austenitic stainless steel for nuclear fusion with the PWHT were investigated. The observation on the microstructure and mechanical properties change in weld were carried out by employing optical microscopy and scanning electron microscopy. The results show that the microstructure of the weld was fully austenite structure, and no precipitated phases were observed. The PWHT has a little effects on the tensile properties of the welded joint, the fracture of the tensile sample were all located at the base metal, while the elongation was enhanced notably after the PWHT. In the low temperature impact tests of the welded joints, the good resistance to this impact emerged, and the impact fracture mode of all samples were presenting ductile fracture according to the fracture analysis.

Design and preliminary experimental study of flowing liquid lithium loop

HUANG Ming, ZUO Gui-zhong, MENG Xian-cai, REN Jun, SUN Zhen, XU Wei, HU Jian-sheng

2017, 37(3): 346-353. DOI: 10.16568/j.0254-6086.201703018

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The thermodynamics of the platform and liquidity of liquid Li are analyzed by ANSYS code. By adding thermal shield and using He cooling in the inner of vacuum chamber, the vacuum chamber temperature can be controlled below 180℃ when the limiter operation temperature heats up to 350℃. By temperature analysis of intersection of Li pipeline and vacuum flange, the water-cooling can effectively control the temperature of the flange knife-edge position. According to the requirement of Li flow rate~2m³•h^-1, the friction head loss and local resistance loss in pipe respectively are estimated and the pressure head of electromagnetic pump is 14.2m. According to the analysis results, a set of flowing liquid Li loop system was built and the relevant experiment was carried out. The preliminary experiment results show that liquid Li could smoothly flow in the loop.

Neutronics calculation and activation analysis for CFETR magnet system

QIAO Shi-ji, JIANG Shuai, CHEN Zhi, XU Xie

2017, 37(3): 354-360. DOI: 10.16568/j.0254-6086.201703019

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The Monte Carlo neutron transport code (MCNPX) is used to carry on the neutronics calculation for CFETR magnet system, and its activation analysis is performed by FISPACT, a European activation calculation code, besides. The calculated results show that the max neutron energy flux is 3.97×10¹⁴MeV•m^–2, which meets the design requirements of the superconducting coil under this condition. The activity of magnet assembly is 3.33×10¹⁰Bq•kg^–1 when reactor is shut down, and after 10-year shut down, the activity reaches 6.14×10⁸Bq•kg^–1, which decreases two order of magnitude. Conclusively, the CFETR 3D model meets the preliminary design requirements and can provide some data support for the construction of CFETR.

Experimental study on NSN70 heat-insulating film produced by magnetron sputtering

JIANG Heng, DAI Bin, RAO Min

2017, 37(3): 361-365. DOI: 10.16568/j.0254-6086.201703020

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Using magnetron sputtering technique, NSN series of heat-insulating films were produced by AgCu alloy deposited on the PET substrates. The NSN series of heat-insulating films solve the problem that single Ag is easily vulcanized in the atmosphere. With the proper AgCu alloy target, the structural design of NSN series of heat-insulating film products, the pattern detection of the NSN films，the weather resistance of the NSN films and the difference between the NSN films and single Ag insulation film on the spectral selection performance were studied. These results lay the foundation for the large-scale industrial production of NSN series heat insulation film in the future.

Effect of particle packed on properties of synthetic ozone by dielectric barrier discharge

QIAN Shu-lou, WEI Jun, QIN Yu-chuan, WANG Cheng, XIA Wei-dong

2017, 37(3): 366-372. DOI: 10.16568/j.0254-6086.201703021

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In order to improve the ozone concentration and energy efficiency, the particles of glass bead, alumina ceramic, quartz and fused quartz are packed in the discharge gap of DBD ozone generator with the structure of coaxial, columnar, single medium and bilateral cooling water, respectively. The effects of the materials, particle size, and gap width on the synthetic ozone were studied. The research results show that the dielectric constant is the main factor that affects the ozone production, with the increasing of it, breakdown voltage of gap reduces, but due to the distortion of electric field, the reduced field rises, the maximum energy efficiency of ozone decreases and saturated concentration rises. Alumina ceramic has the best saturated concentration which has increased by 136%, compared with the empty bed. With the particle size increases, the breakdown voltage of gap and reduced field rise, the maximum energy efficiency decreases, but the saturated concentration rises. Moreover, the result of packed particle in the wide gap can reach the same results of the narrow gap.

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