Table of Content

15 September 2010, Volume 30 Issue 3

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Plasma Physics

Seed parallel Reynolds stress induced by spontaneous symmetry breaking

ZHANG Yang-zhong

2010, 30(3):  193-196. 

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The ballooning theory of the second kind anticipates the spontaneous radial symmetry breaking of unstable toroidal local modes in tokamak such as drift waves owing to toroidicity. Taking the fluid model equation of ion temperature gradient driven mode to be an instance, the two-dimensional local mode structure associated with the symmetry breaking is solved. When the sideband is neglected, it is reduced to the modified slab wave function by the radial shift. The modified slab wave function is used to yield the seed parallel Reynolds stress, which would otherwise (as in the traditional slab wave function) be zero.

Effect of ablated-plasma on the implosion dynamics of wire array Z pinches

ZHANG Zheng-wei, DING Ning, HUANG Jun

2010, 30(3):  197-202. 

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A self-consistent ablation-implosion model was established in which Rocket model and snowplow model were well combined. The effects of ablated plasma on the implosion dynamics of wire array Z pinches were studied and a rational implosion trajectory was obtained. The implosion time, velocity and kinetic energy were calculated and the results were compared with that of the zero-dimension thin shell model. It was found that the implosion kinetic energy and the mass of wire array (per unit length) for the maximal kinetic energy calculated from our model was less and smaller than the zero-dimension model respectively.

Preliminary application of maximum likelihood method in HL-2A Thomson scattering system

YAO Ke, HUANG Yuan, FENG Zhen, LIU Chun-hua, NIE Lin, LI En-ping

2010, 30(3):  203-207. 

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Maximum likelihood method to process the data of HL-2A Thomson scattering system is presented. Using mathematical statistics, this method maximizes the possibility of the likeness between the theoretical data and the observed data, so that we could get more accurate result. It has been proved to be applicable in comparison with that of the ratios method, and some of the drawbacks in ratios method do not exist in this new one.

Experimental study of FIR laser interferometer and density ramping on EAST tokamak

WANG Er-hui, GAO Xiang, JIE Yin-xian, YANG Yao, SHI Nan, LIU Zi-xi, MING Ting-feng

2010, 30(3):  208-212. 

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A single-channel far-infrared (FIR) laser interferometer is developed for measuring the line averaged electron density (R=1.82m) of the main plasma on EAST tokamak. While main plasma density is raised by gas puffing, three different divertor regimes, i.e., low recycling (low divertor plasma density, high temperature), high recycling (high divertor plasma density, low temperature), and detached divertor plasma (low divertor plasma density, low temperature), are first obtained on EAST tokamak. The physical phenomena of these regimes on EAST tokamak are presented briefly.

Flux consumption optimization during plasma ramp of EAST tokamak

LIU Cheng-yue, CHEN Mei-xia, WU Bin, HU Ya-min

2010, 30(3):  213-216. 

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The Poynting method for the calculation of flux consumption is described, and the flux consumption optimization is carried out by the scan of plasma current ramp rate. The results provide some reference for the long-pulse steady-state discharge on EAST tokamak.

Evolution of the electron phase orbits in the multi-photon nonlinear Compton scattering in plasma

HAO Xiao-fei, YIN Gang, HAO Dong-shan

2010, 30(3):  217-219. 

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The evolution of the electron phase orbits in the plasma under the multi-photon nonlinear Compton scattering is discussed by using KMR model. There is an evolution from periodicity to non-periodicity of the only un-captured electron phase orbits after the energy exchange between an electron beam and photons is found. Along with the increase of the absorbed photon number by an electron, this evolution will be more and more faster, while it is rapidly decreased along with the enhancement of the collision non-flexibility between an electron and photons and the initial speeds of the electron before the scattering. But, the strenuous degree of the evolution is lower than that in the high power laser field. When the electrons are captured by the laser field, the evolution is finished, the electrons will stably transport, and the photons don't give the energy to these electrons.

Rayleigh scattering for a magnetized cold plasma sphere

LI Ying-le, LI Jin, WANG Ming-jun, TANG Gao-feng

2010, 30(3):  220-224. 

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The transformation of parameter tensors for anisotropic medium in different coordinate systems is derived. The electric field for a magnetized cold plasma sphere and the general expression of scattering field from anisotropic target are obtained. The functional relations of differential scattering cross section and the radar cross section for the magnetized plasma sphere are presented. Simulation results agree with that in the literatures, which shows the method used is correct and therefore the results may provide a theoretical base for anisotropic target identification.

Analysis of magnetized plasma photonic crystals on the basis of the faraday effect by finite-difference time-domain method

LIU Song, LIU Shao-bin

2010, 30(3):  225-229. 

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The photonic band gap (PBG) structures of plasma photonic crystals (PPCs) can be turned after being added an applied magnetic field. The PPCs consisting of an intrinsic plasma layers and other dielectric material layers stacked alternately, is taken as an example in studying photonic band gap structures and transmission spectra within the magnetic field using finite-difference time-domain (FDTD) algorithm. A perfectly matched layer absorbing boundary condition is employed to deal with the numerical non-reflection boundary in these simulations. Due to the Faraday effect, the dielectric constant of the plasma is modified differently in different frequency ranges. As a result, the PBG characteristics of the PPCs are turned correspondingly. Interestingly, the electromagnetic wave transmission below the plasma frequency can be realized.

Nuclear Fusion Engineering and Technology

Control and protection system based PLC for the ECRH system on the HL-2A tokamak

ZHAO Lei, LI Li, Bu Ying-nan, FENG Kun, LI Bo, RAO Jun

2010, 30(3):  230-235. 

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The design and implementation of the control and protection system which was build up around the SIEMENS S7-300 PLC in the ECRH system on the HL-2A tokamak is introduced. The system uses the distributed architecture based on industrial Ethernet. And the system also uses fiber isolation technology to transmit high voltage/high current measurement and control signals in order to ensure the security and the stability of the system, while enhancing the anti-jamming capability of the signals during the transmission process. The heating protection system adopted the fast protection technology based on CPLD/FPGA. It has proved that the control and protection system is stable, reliable and compatible with the strong electromagnetic interference on the HL-2A. The whole system is also fully functional and has a good scalable performance.

Transmission efficiency of the ECRH system on HL-2A tokamak

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

2010, 30(3):  236-240. 

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The method for measuring the transmission efficiency of the HL-2A ECRH system is presented. The efficiency is about 90% by measuring the microwave power absorbed calorimetrically in the MOU, gyrotron output window and torus window of the EC system. A method of measuring power through parts of the transmission line besides MOU is provided.

Design of embedded control system for high-power tetrode modulator

TU Rui, YAO Lie-ying, XUAN Wei-min

2010, 30(3):  241-244. 

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The design of embedded control system for the high-power tetrode modulator and its test results are given. This control system is a closed-loop feedback system based on the DSP and embedded into the high-voltage modulator. A new modified method of VF fiber transmission is used in the embedded control system. The new method improves the speed of the transmission of feedback system. The results of the experiment demonstrate that the embedded feedback control system greatly increases the response speed of the whole system and improves the performance of the high-power tetrode on the HL-2A tokamak. This embedded feedback control system greatly simplifies the complexity of the original centralized control system. The operation of the control system is reliable.

Key technology research on EAST PFCs heat-sink cooling structure

XU Tie-jun, HUANG Sheng-hong, SONG Yun-tao, XIE Han, ZHANG Ping, GAO Da-ming

2010, 30(3):  245-249. 

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Cooling effect decline of the plasma facing components (PFCs) due to tube in heat-sink was studied experimentally and numerically. In the same heated wall condition, a heat exchange performance comparison is made among the processing technology of no tube in heat-sink, using high pressure to ensure residual stress between cooper tube and heat-sink, and high temperature vacuum welding. Numerical simulation was carried out, and a reasonable calculation models and parameters were determined. A heat-sink prototype heat exchange performance comparison is made between the processing technology of using high pressure and high temperature vacuum welding, to provide the basis for EAST PFCs cooling structure optimization.

Thermal-structure analysis of the straps on ICRH antenna for EAST tokamak

WANG Cheng-hao, SONG Yun-tao, YANG Qing-xi, WANG Zhong-wei, KANG Qin-lan

2010, 30(3):  250-254. 

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The structure of the straps on new type of ICRH antenna for EAST tokamak was introduced. Based on the calculation of the condition in which straps would work, the work temperature distribution of the straps could be obtained. Using this result, the straps resistance to thermal load and its influent on the strap structure under the operation condition are simulated. It is demonstrated that the radiation surface temperature and overall structure strength of the straps under the real thermal load (0.2MW) satisfy the design requirements.

Discussion of bolts in alternative design of ITER TF magnet gravity supports

HOU Bing-lin, LI Peng-yuan, PAN Chuan-jie, HAN Shi-lei

2010, 30(3):  255-260. 

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The forces of the bolts applied are analyzed by analytical calculation. All the bolt preloads are calculated and all the bolt parameters are designed. The loosening prevention of the bolt is introduced. Engineering test studies of full-scale for the bolts model and the assembling model of the gravity support(GS) structure are presented in order to improve the reliability of the bolts for the new designed GS, which offers the engineering reference for the bolt structure design of the ITER TF magnet GS.

Electromagnetic analysis of ITER shield blanket under VDE

KANG Wei-shan, CHEN Ji-ming, WU Ji-hong, WANG Ming-xu

2010, 30(3):  261-266. 

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Electromagnetic force and torque of ITER shield blanket system and their surrounding major component under vertical displacement event (VDE) were calculated with finite element method. ANSYS APDL was used to simulate the shape and magnitude of plasmas current dynamically in the VDE course, and external magnetic field was imposed, then the induced current distribution inside the all conductor including the blanket was obtained from the calculation. The force and torque for every blanket module was obtained to assess the safety of blanket system under VDE.

Thermal-hydraulic analysis for ITER shield block

ZHANG Xiu-jie, CHEN Ji-ming, KANG Wei-shan, YUAN Tao, WU Ji-hong

2010, 30(3):  267-271. 

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Thermal-hydraulic analysis was performed for ITER shield block using CFD code ANSYS CFX. Two different types of computational meshes were given for the same numerical model, the effect of meshes on the numerical precision was studied in the simulation and it indicated that there is good numerical accuracy for the two types of meshes. The effect of wall roughness on the flow and heat transfer was studied through numerical simulation; the results show that it is an important element for wall roughness in heat transfer computation.

Design and analysis on ITER axial insulation breaks

YANG Chang-chun, PAN Wan-jiang

2010, 30(3):  272-276. 

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The electrical analysis and mechanical analysis on structure of insulator for ITER magnetic systems are made by finite element method. The results show that the composite insulation breaks can withstand 56kV high voltage, 4MPa inner gas pressure, 2000N tensile force, 1000Nm bending moment and 100Nm torsion. The results of thermal stress analysis indicate that thermal stress is a key factor comparing with influence of outer mechanical leads.

Measurement of outgassing rate of magnetic probe in the SUNIST spherical tokamak

ZHANG Lu, ZENG Long, TAN Yi, XIE Li-feng, GAO Zhe, WANG Wen-hao

2010, 30(3):  277-280. 

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The outgassing characters of probes installed inside the SUNIST vessel are evaluated by the device for measuring outgassing rate. The results show the influence isn’t important to the vacuum of SUNIST spherical tokamak. The discharging experiment supports this issue.

Non-Fusion Plasma Applications

Study on parameter of dust particles in polar summer mesopause

LI Hai-long, NIU Jun, WU Jian, CHE Hai-qin

2010, 30(3):  281-284. 

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The orbit-limited motion method is adopted to study the dust charge number and the radius of dust particles in polar summer mesopause. Based on the charging theory of dust particles in the dusty plasma, the equation of dust grain charging is formed, and the formula of the ratio of dust charge number to the radius of dusty particle at the charging of dusty particle is deduced. On the basis of the data of ECT02 campaign, the ratio of dust charge number to the radius of dust particle at occurring polar mesosphere summer echoes(PMSE) is analyzed, then the dust charge number and the radius of dust particle are obtained. The results show that the average charge number of dust particle in the polar mesopause is less than one and the average radius of dust particle is about 20 nm.

Time effectiveness of capillary effect improvement of ramie fabrics processed by RF glow discharging

WANG Zhi-wen, WEI Wei-xing, HE Yan-he, ZHAO Yuan-qing, PAN Li-yi-ji, LI Xue-mei, SHI Shao-dui, LI Guang-xin

2010, 30(3):  285-288. 

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The time effectiveness of capillary effect improvement of ramie fabrics processed by RF glow discharging was studied. The ramie fabrics were processed in fulfilling with different gas (O2, N2, Ar) by different parameters (such as pressure, power and time) plasma. The capillary effect of the ramie fabrics processed by RF glow discharging was tested at different time. The results indicate that the capillary effect of ramie fabrics processed by RF glow discharging has been improved, the improvement of the capillary effect firstly decrease rapidly, then slowly, and become stable after 15 day, it indicate that improvement of the ramie fabrics capillary has good time effectiveness, and the plasma parameter for the best capillary effect improvement of ramie fabric is 100W and 40Pa processed 20mins by oxygen plasma.