Table of Content

15 September 2007, Volume 27 Issue 3

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Research Report

Study of laser blow-off system on the HL-2A tokamak

ZHANG Peng, HUANG Yuan, SUN Ping, FU Bing-zhong, Lu Jie, CUI Zheng-ying, DING Xuan-tong

2007, 27(3):  177-181. 

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A new auto-control system of laser blow-off on the HL-2A tokamak has been designed. It can accurately control the quantity of injected impurity, the target displacement and the trigger time. The study indicated that when the quantity of injected impurity was kept in suitable level, injected impurities do not make influence on plasma confinement but give convenience for spectrum measurement and impurity transport research. The design of laser blow-off system and experimental result are presented.

Research of influence of wall on the stability of non-circular toroidal plasma

QIAHAN.Hezier

2007, 27(3):  182-187. 

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Based on the energy principle of B Bernstein, steady analytical results of plasma for arbitrary aspect ratio and arbitrary elongation ratio of non-circular toroidal plasma surrounded by wall, without any approximate methods, are evaluated by introducing cap-cyclide coordinates and applying Wangerin function. Further more, the influence of wall on the stability of non-circular toroidal plasma is analyzed and discussed using the relationship between β and a safety factor q.

An approximate prediction of the radiation spectrum from Z-pinch plasmas

DUAN Yao-yong, GUO Yong-hui, KUAI Bin, QIU Ai-ci

2007, 27(3):  188-193. 

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With the laboratory plasmas radiation and a three-temperature plasma model for Z-pinch, an approximate prediction of the radiation spectrum from Z-pinch is proposed. The mathematical method is incorporated into a two-dimensional, three-temperature radiation magneto-hydrodynamics model for the simulation of the krypton gas-puff Z-pinch, and the energy spectra has been obtained. In comparison with the experimental results on “Qiangguang-I” accelerator, the differences between the predicted and the experimental data are analyzed.

Theoretical calculation of M-band spectrum for Au using correctional UTA model

OU Yang-yong-zhong, TANG Ge, YI You-gen, ZHU Zheng-he, ZHENG Zhi-jian

2007, 27(3):  194-197. 

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Unresolved transition array model and multi-configuration Dirac-Fock (MCDF) method are applied to calculate the line and band spectrum of laser-produced gold plasmas in the 0.40～0.62nm range. The better agreement between theoretical and experimental measurement compared with the results of the calculation only using the UTA model indicates that it is reasonable and necessary to correct the UTA model using MCDF method when the transition array contains only a few lines and the distribution of the lines are very thin.

Differential scattering section of multi-photon nonlinear Compton effect in high power laser-plasma

HAO Dong-shan, HENG Yao-fu

2007, 27(3):  198-202. 

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The scattering of the damped electron and photon with the multi-photon nonlinear Compton effect in the high power laser-plasma is studied.Its differential scattering section is also given. The result shows that the fluctuation and random error of Wiggler field are the basic factors which cause electron clustering in vertical direction in the plasma and can lead a consequent acuter electron clustering. The changes of the electron transverse momentum are the basic factors of electron and photon scattering，and their differential scattering sections are decreased with increasing of the quantity of photons which are active with an electron at the same time，and they are quickly decreased with the increasing of the inelastic scattering composition，but their change are slower than that in the situation dominated by laser field. When the active photon number with an electron at the same moment is equal to the inelastic scattering composition，the electrons can only be captured by the laser field.

Calculation of electrode cooling in glow discharge on ITER

ZENG Jian-er, ZOU Gui-qing, RANG Hong

2007, 27(3):  203-207. 

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The calculated results for cooling electrode based on the previous design are presented. When the power is 9000W in glow discharge conditioning, the temperature of electrode cooled by water with speed of 4~6 m•s^-1 will not be over 100°C, and the temperature will not be over 200°C when the electrode is cooled by Helium with speed of 300m•s^-1. The calculation shows that cooling by water is more efficient than by Helium.

Mechanical structure and support design for ITER PF superconducting busbar

ZHANG Yuan-bin, WU Song-tao

2007, 27(3):  208-211. 

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Mechanical structure and support design of ITER poloidal field busbar were expounded and stress analysis was carried out using FEA technique. According to the analytical results, preliminary support design was given and final support setup optimized with ANSYS code was achieved.

Primary analyses of plasma parameters for HCSB-DEMO reactor

ZHENG Guo-yao, FENG Kai-ming

2007, 27(3):  212-216. 

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Due to the requirements of HCSB-DEMO reactor design, fusion powers, neutron wall loadings and plasma burn times in the fusion reactors with different sizes are investigated. Reactor parameters are selected and analyzed with the POPCON code. Three group plasma parameters suitable for HCSB-DEMO reactor are given.

Implementation and design of monitoring and control system in the power supply system for EAST poloidal field

YANG Ya-long, CHEN Fei-yun, FU Peng, HE Shi-ying

2007, 27(3):  217-221. 

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The monitoring interface is designed using configuration software. By means of this interface, the monitoring node can communicate with the high voltage monitoring node and field bus controllers, so the status of the poloidal field power supply system can be monitored in real time reliably. Meanwhile, the monitoring data will be sent to database node for backup through ODBC. The structure of the power supply monitoring and control system is briefly described. The procedure of real-time data transfer and processing is realized by different communication protocols.

Analysis of EAST vaccum vessel load due to HALO current

SONG Yun-tao, PENG Yu-hua

2007, 27(3):  222-226. 

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Based on the abundant experimental data from some big size tokamak device, the driving of HALO current was understood. At the same time the numerical simulation methods was used to investigate the HALO damage to the structure of tokamak device considering the toroidal asymmetric characteristic of the HALO current. Finally an engineering theory and science analysis method will be summarized, which could help to develop the design criteria for the future tokamak fusion reactors.

Design and implementation of the protection for LHCD antenna transmission line on EAST tokamak

JIA Hua, XU Hui, LIU Fu-kun, WANG Mao, SHAN Jia-fang

2007, 27(3):  227-230. 

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The design and implementation of the protection for LHCD antenna transmission line on EAST tokamak are described in detail. The reasons causing damage to the ceramic windows of the lower hybrid wave(LHW) system on EAST are analyzed, then two safeguards including high reflection protection and arc protection have been designed on the antenna transmission line to avoid the damage. Especially, the arc protection will shut down the microwave output in less than 20?s after arcing. Experimental results prove that the double-acting protections worked at the same moment, and protected the whole system efficiently.

Read-out of laser Thomson scattering signal on the HT-7 tokamak

SHI Ling-wei, ZANG Qing, XU Ya-jie, HU Qing-sheng, LING Bi-li, ZHAO Jun-yu

2007, 27(3):  231-236. 

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In order to get high signal-to-noise ratio, silicon avalanche photodiode (APD) is used to measure Thomson scattered spectrum. A charge-sensitive preamplifier has been developed for minimizing the noise contribution from detector electronics. Many measures are taken, including a new design electronic amplification circuit and a series of anti-interference technique. Therefore the Thomson scattering diagnostic system is successful to measure the plasma electron temperature on HT-7 tokamak.

Numeric simulation of CICC design based on optimization of ratio of copper to superconductor

JIANG Hua-wei, LI Yuan, YAN Shuai-ling

2007, 27(3):  237-241. 

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For cable-in-conduit conductor (CICC) structure design, a numeric simulation is proposed for conductor configuration based on optimization of ratio of copper to superconductor. The simulation outcome is in agreeement with engineering design one.

Effect of SiC gradient coating on the properties of doped graphite

LIU Zhan-jun, GUO Quan-gui, SHI Jing-li, ZHAI Geng-tai, LIU Lang

2007, 27(3):  242-246. 

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Thick SiC gradient coating on the surface of the doped graphite was prepared by chemical vapor reaction. The effect of SiC gradient coating on the thermo-mechanical properties as well as microstructure of the doped graphite was investigated. Results showed that the thermal conductivity of the doped graphite decreased, while the mechanical strength increased when the SiC was coated on the surface of the doped graphite with a thickness about 100μm. Phase composition analysis revealed: there were strong SiC diffraction peaks and weak Si diffraction peak for the coatings. Grain size and structure of SiC was changed, and thickness of the SiC coating decreased from 100μm to 30μm after discharge experiments in HT-7 device during the autumn operating season of 2005.

Research on electric and thermal characteristics of plasma torch based on similarity theory

CHENG Chang-ming, TANG De-li, LAN Wei

2007, 27(3):  247-250. 

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Configuration and working principle of a DC non-transferred plasma torch have been introduced. Based on similarity theory, connections between the electric-thermal characteristics and operational parameter such as flowing gas rate and arc power have been investigated. Calculation and experiment are compared. The results indicate that the calculation results are in agreement with experimental ones. The formulas can be used for plasma torch improvement and optimization.

Numerical simulation of compact toroids acceleration process

JIANG Meng, WANG Shang-wu

2007, 27(3):  251-255. 

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Acceleration mechanism of a compact toroid (CT) is analyzed in detail, and the CT speedup process is described by a set of radiation magneto-hydrodynamics equations in this paper. A two-dimensional simulation code is programmed by means of Lagrange scheme, and is utilized to calculate the speedup process of a 10mg Ar CT in a coaxial acceleration facility. The change of accelerating current and radiation power with time, the radial distribution of CT speed and plasma temperature are obtained during the speedup process.

Research of electromagnetic field in different length left-handed material slab

LIN Zhen1, MA Xue-ying1, LIANG Chang-hong1, ZENG Hao2

2007, 27(3):  256-259. 

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Finite-difference time-domain (FDTD) method is used to simulate the propagation of electromagnetic wave in left-handed material slab (LHMs) with cold plasma model The effects of optical propagation in the left-handed material compared to convex lens are discussed. The wider the LHMs is, the stronger electric field of focusing image in left-handed material slab is confirmed by the simulation with various slab length. However, the outer image point location would slightly moves to the LHMs side when the length of LHMs is reduced.

Soft X-ray signal data acquisition and processing based on general equipment and special software

LIAO Min, YANG Jin-wei, CHEN Liao-yuan, LI Yong-ge, LUO Cui-wen, PAN Wei, SONG Xian-ying

2007, 27(3):  260-263. 

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Signal data is acquired using general high-speed A/D acquisition card and processed by the software which has the multi energy pulse recognizing ability and the count-analyzing ability. The software realizes energy impulse data mining and calculating, and gives the energy figure from the large amount of riginal data after every tokamak discharge. It is data base for measuring electron temperature and realizes the data-share at the same time.

Radio-frequency influences on Cu film deposited by unbalanced magnetron sputtering

QI Xue-lian, REN Chun-sheng, ZHANG Jian, MA Bing-xin, MA Teng-cai

2007, 27(3):  264-268. 

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Metallic copper films are deposited on Si100 substrate by radio-frequency plasma enhanced unbalanced magnetron sputtering, and film performance is studied by changing deposition parameters such as bias voltage, rf power and magnetron. The morphology, structure and element of the films are examined by scanning electron microscopy, atomic force microscope (AFM), X-ray diffraction (XRD) and electron spectroscopy (EM). The results show that rf discharge has advantages in depositing equality smooth and high conductivity Cu film and deposition parameters are important for film performance.

Elementary study for modification and dyeing of polypropylene fiber by N₂ plasma and graft treatment

PENG Sai-ping, SU Yuan, HE Quan-guo, GE Yuan-jing, CHEN Qiang

2007, 27(3):  269-272. 

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A method to improve the dyeing property of polypropylene (PP) fiber surface by nitrogen (N₂) plasma treatment and acrylic acid (AA) grafting is presented. The surface modification was characterized by Fourier transformed infrared spectra (FTIR) to analyze changes of chemical groups, and the PP fiber morphological appearance changes were verified by scanning electronic microscope (SEM) as well as subsequent dyeing ratio thereby was determined by ultraviolet-visible spectra (UV spectrometer) detection. The results demonstrated that N₂ plasma treatment and AA grafting facilitated reactive groups (such as carbonyl group, amine group or amide group, etc) generation on PP surface, which was ameliorated to be conveniently dyed or colored with bright-colored basic blue 54 dyestuff. The investigation demonstrates an amelioration method of PP fiber surface dyeing property from inert to active.