Table of Content

15 June 2016, Volume 36 Issue 2

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Plasma Physics

Design of tungsten divertor unit and its related experiments

CAI Lai-zhong1, CAI Li-jun1, YAN Jian-guo2, HAN Le3,DING Rui4, LIU Xiang1, BI Qin-cheng2, ZHANG Jing-yang3

2016, 36(2):  97-103.  DOI: 10.16568/j.0254-6086.201602001

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In study of the unit of the tungsten divertor, the effects of different parameters of the unit such as the size of the tungsten target plate, the cooling structure and the flowing parameters of the cooling water are focused on in this paper. The directions of design and optimization of the divertor unit and its cooling structures for both the divertor target plate and the dome are given. In addition, the validation of the performance of the cooling structures is implemented by experiments under high heat fluxes. Finally, the stress and safety of the divertor units under mechanical loads, high heat loads and electromagnetic loads due to transient events in a tokamak are analyzed and discussed.

Progress of motional Stark effect polarimeter in HL-2A tokamak

CHEN Wen-jin1, HE Xiao-xue1, LIU Liang1, WEI Yan-ling1, MA Qian2, YU De-liang1

2016, 36(2):  104-110.  DOI: 10.16568/j.0254-6086.201602002

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Two types of motional Stark effect (MSE) polarimeters were detected and the pilot experiments of measuring the magnetic pitch angle are carried out in the HL-2A tokamak. The main part of the first type consists of 4 polarizers and a spectrometer, and the accuracy of ±0.15° can be obtained. The pitch angles of magnetic field are achieved by 7 spatial channels covering 24 cm major radius with time resolution of 40 ms. The profiles of safety factor are obtained by combining with the equilibrium and reconstruction fitting code (EFIT). The position of q=1 surface is well consistent with the results measured by soft-X array. The other one based on a dual photo-elastic modulator (PEM) can obtain the accuracy of ±0.15° in the calibration experiments. The deviation angle between analyzing polarizer axis and the angular bisector of the dual PEM influences heavily on the linearity and the accuracy of the system. Time resolution of 20 ms was obtained for one channel during the pilot experiments.

Design and optimization of ploychromator in HL-2M Thomson scattering system

WANG Yu-qin, HUANG Yuan, LIU Chun-hua, FENG Zhen

2016, 36(2):  111-118.  DOI: 10.16568/j.0254-6086.201602003

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A new kind of polychromators is designed and optimized. It is easy to install the APD modules and interference filters, to reduce the optical path and improve the ability to detect scattering light, and to increase the transmittance of polychromator with decreased quantity of optical lens in this scheme. After a series of numerical simulation, the design of 7-optical channel detection is the best when the temperature ranges from 200eV to 20keV. At last, the related parameters of the 7 channel polychromator are designed and optimized, and the wavelength range of interference filters in each channel is optimized by simulating annealing method.

Experimental study on intrinsic impurity induced snake for EAST tokamak

MA Tian-peng1, XU Li-qing2, HU Li-qun2

2016, 36(2):  119-125.  DOI: 10.16568/j.0254-6086.201602004

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The dynamics and spatial structure of intrinsic impurity induced core 3D snake instability were experimentally studied by means of multi-arrays high temporal and spatial resolution soft X-ray imaging system in EAST. Two types of spontaneous snake were identified regarding to the relationship between sawtooth and snake. The frequency spectra of first type snake is shaped as letters ‘V’ or ‘W’, and the structure of hot core appear in circular. Another type of snake coexists with sawtooth crash. The frequency spectra of this type snake are shaped like a palm, and it grow to a large crescent-shaped helical island-like structure. The second type snake with a bigger radial displacement than the first one and it can trigger 2/1 new-classical tearing mode via mode coupling.

Optimization of output power on far infrared waveguide DCN laser by continuous glow discharge

WEI Xue-chao, SHEN Jie, JIE Yin-xian, ZENG Long, LIU Hai-qing

2016, 36(2):  126-130.  DOI: 10.16568/j.0254-6086.201602005

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The far infrared laser interferometer on EAST, DCN laser, is introduced. Helium, CD₄, D₂ and N₂ are used in the laser. The output power is optimized by changing the supply current, gas pressure and gas ratio. Experimental results show that the best parameter can be achieved with the gas ratio He: CD₄: D₂: N₂=2: 3: 5: 3 and gas pressure 32Pa. The output power increases with current increase.

Equilibrium reconstruction and its integration in J-TEXT

ZHANG Fan1, 2, XU Tao1, 2, GAO Hai-long1, 2, ZHANG Xiao-qing 1, 2, ZHUANG Ge 1,2

2016, 36(2):  131-135.  DOI: 10.16568/j.0254-6086.201602006

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The Matlab language is used to integrate the equilibrium fitting code (EFIT), which simplifies the code’s procedure and adds the analysis function to the results. In the calculation of equilibrium reconstruction, the improved EFIT code is used to get the pressure of plasmas, internal magnetic surface and plasma current density profile. In addition, the results of the calculation are compared with the experiment data from the X-ray. The results show that the improved EFIT code can meet the basic requirements to the equilibrium reconstruction calculation, and it can provide important reference data for the operation and control of the J-TEXT tokamak discharges.

Nuclear Fusion Engineering and Technology

Structural design of HL-2M toroidal field coils

ZOU Hui, LI Guang-sheng, CAI Li-jun, LIU Jian, QIU Yin, SHAN Ya-nong, LU Yong

2016, 36(2):  136-142.  DOI: 10.16568/j.0254-6086.201602007

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The HL-2M TF coils shape, demountable joints, feeding & return bus, electrical insulation and cooling loop were designed. Each TF coil is assembled with L-shape center section, upper arc section and outer arc section, by finger joint and scarf joint to constitute complete D-shape coil. Demountable D-shape coils allow the vacuum vessel and individual poloidal field coils to be settled in the space within the TF coils integrally. The single feeding bus and two return buses located symmetrically, save the space and reduce the stray field. The TF coils are insulated electrically to 500V per turn and 30kV to ground. The coils are water-cooled using copper tubes soft-soldered into grooves in the sides of the coils in order to remove the Joule heat produced by the coils discharge.

Preliminary design and structural analysis for HCSB TBM shield module

WU Xing-hua, WANG Xiao-yu

2016, 36(2):  143-147.  DOI: 10.16568/j.0254-6086.201602008

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Preliminary design for HCSB TBM shield was introduced. Structural analysis was carried out in accordance with RCC-MR standard, under four typical load conditions. Preliminary results show that the overall deformation is very small, and the primary and secondary stresses are all well below the allowable values.

Analysis of HCSB DEMO neutron flux spectra and conceptual design of detection system based on foil activation method

FENG Yong, LI Zai-xin, ZHAO Feng-chao

2016, 36(2):  148-153.  DOI: 10.16568/j.0254-6086.201602009

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Monte Carlo particle transport code (MCNP) was applied to build the model of HCSB DEMO. The neutron flux spectra of HCSB DEMO has been analyzed. The foils were selected according to characteristics of the neutron flux spectra. Based on the rabbit radiation system and the foil activation method, the preliminary design of the neutron detection system was performed, which can be applied to detect the breeder blanket neutron of HCSB DEMO. The functions of the components of the system was introduced. The specific reaction rates of the foils were calculated when the foils are irradiated in the irradiation station of the detection system in HCSB DEMO. The emission rates and the counting rates of the characteristic γ rays were calculated. A reasonable operation scheme of the system was obtained and it can be used to detect the breeder blanket neutron.

Simulation and analysis of the outlet temperature control of flowing helium gas

WANG Fen, FENG Kai-ming, WANG Xiao-yu, YE Xing-fu, ZHANG Guo-shu

2016, 36(2):  154-159.  DOI: 10.16568/j.0254-6086.201602010

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The heating process of flowing helium gas by the electric heater was analyzed. The system mathematical model was established from the perspective of energy balance. The PID control framework was adopted using Matlab Simulink module. To improve the effect of the temperature control, the PID control was optimized by the integral separation. Simulation results show that in the case where the fluid inlet temperatures change, a relatively stable gas outlet temperature is obtained by adjusting the heater power, and a good control is gotten.

Feedback control system for baking temperature of vacuum chamber on HL-2A tokamak

XU Jie, DONG Fang-zheng, TANG Fang-qun, TIAN Pei-hong

2016, 36(2):  160-166.  DOI: 6086.201602011

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Temperature feedback control system of the HL-2A tokamak vacuum chamber baking is designed. The approximate mathematical model was adopted by experimental method, and the step response model of HL-2A baking system was established. Design analysis of system performance index was applied by the control theory, stability analysis of control system was conducted by Simulink software, and the system of hardware and software was implemented with Siemens PLC300 system.

Management automatic system of EPICS process variable on HL-2A tokamak

LI Xin-yi1, XIA Fan1, YANG Chao2, PAN Li1, ZHANG Gang1, CHEN Liao-yuan1

2016, 36(2):  167-173.  DOI: 10.16568/j.0254-6086.201602012

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Through the analysis of the problem that a large number of data need to be defined and converted when subsystems access EPICS platform, the structure of EPICS IOC database and data structure were researched. Management automatic system of EPICS process variable based on ASP.NET and C#, is developed successfully with a corresponding interface. This system solved the problem of IOC PV information collection and data security, implemented the bulk PV storage, PV rights management, record query and real-time updates, etc.

Numerical study on beryllium dust distribution during LOVA in ITER

HOU Li-qiang，TONG Li-li

2016, 36(2):  174-180.  DOI: 10.16568/j.0254-6086.201602013

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The three-dimensional numerical model of ITER, where the design structure was reasonably simplified, was built by computational fluid dynamics (CFD) method. The migration process of dust composed of beryllium in ITER during a LOVA was reproduced. The dust distributions at different heights and moments were analyzed. And it was found that the volume fraction of beryllium dust had a downward trend as the height increases and that the volume fraction of beryllium dust has an upward trend as time went.

Structural design and analysis of torus cryopump housing for ITER

XIE Han1, 2, SONG Yun-tao1, WANG Song-ke1

2016, 36(2):  181-187.  DOI: 10.16568/j.0254-6086.201602014

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The cryo-pump for ITER vacuum vessel needs regeneration regularly to remove the gas, and the accumulated density of hydrogen cannot be higher than 1.5mol⋅m⁻³ due to the concern of nuclear safety and the overall volume for regeneration need at least 15m³. Therefore the cryo-pump needs extra volume provided by housing which also support and seal the cryo-pump. The structure and function of torus cryo-pump housing are introduced, and the associated finite element analysis and assessment justify the design feasibility.

Non-Fusion Plasma Applications

Fluid model of the free liquid tin surface structure

ZHU Zhi-chuan1, GOU Fu-jun2, HUANG Yi1, MIAO Feng1, ZHANG Chuan-wu1

2016, 36(2):  188-192.  DOI: 10.16568/j.0254-6086.201602015

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The structure model of the free flow liquid tin is designed by SolidWorks software, the speed changes and temperature changes of liquid tin are calculated under different initial velocity and heat flux by ANSYS software, and the velocity distribution and temperature distribution of liquid tin has been obtained. Also, the calculated results show that velocity of liquid tin is relatively uniform at the perpendicular to the flow direction, while the velocity of liquid tin increase and the liquid level of liquid tin attenuate gradually along flow direction. Under the condition of initial temperature of liquid tin is 600K,if the heat flux is 1 MW·m^-2,the temperature of liquid tin at outlet is 623.38K; if the heat flux is 5 MW·m⁻², the temperature of liquid tin at outlet is 720.18K.When the liquid lithium as calculated fluid under the same conditions,the results show the temperature of liquid lithium is much lower than that of liquid tin.