Table of Content

15 March 2006, Volume 26 Issue 1

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Contents

Determination of ohmically driven tokamak equilibrium

SHI Bing-ren, QU Wen-xiao , LI Fang-zhu

2006, 26(1):  1-7. 

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For ohmically driven tokamak plasma , the total plasma current is composed of ohmic current and internal self-consistent component. For a simplified Spitzer resistivity model , the toroidal current profile is determined by the electron temperature profile and the effective charge number Z_eff profile at each time. The derivation of the fundamental equation to determine this equilibrium configuration is given. In the large aspect ratio approximation , analytic solution on equilibrium configuration with small non-circular deformations is obtained for sawtoothing plasma.

Correction at finite detector size effect on line-integrated emissivity

QIN Yun-wen

2006, 26(1):  8-12. 

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In tokamak plasma radiation diagnostics ,a relationship between the line-integrated emissivity and the plasma emissivity distribution in the infinitesimal-detector approximation is usually used. It can be shown that this approximation holds only for the detection system with the detector which has a poloidal size much smaller than that of the aperture. For the system with equal-size of detector and aperture, the cross-section of detector chord in plasma is twice as large as that in the infinitesimal-detector approximation. For such system the correction at finite detector size is derived for the line-integrated emissivity expression. The improvement by the correction on tomography analysis is discussed in brief.

Study of electron heat transport by density modulation on HL-2A tokamak

SHI Zhong-bing, DING Xuan-tong, LIU Ze-tian, ZHENG Yin-jia, YANG Qing-wei, XIAO Wei-wen, LI Ying-liang-

2006, 26(1):  13-16. 

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The electron heat transport is studied by analysis of observed cold pulse propagation during gas modulation in HL-2A ohmic discharge. The electron heat transport is analyzed using perturbation transport equation. According to the results of curve fitting and numerical calculation with the electron temperature perturbation measured from modulated gas puffing experiment during ohmic discharge on HL-2A tokamak, the character of the electron heat transport coefficient  profile at high field side is χ = 15 -14 (1 -r ²)²m² ·s ^-1 .

Analysis of stress on the L HCD system during baking the HL22A tokamak

YI Liang-bi, ZENG Jian-er, LI Guang-sheng, ZHANG Jin-song

2006, 26(1):  17-21. 

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Measurement of the LHCD antenna system displacement due to the temperature change is described. The maximal displacement of the LHCD antenna system and the HL-2A vacuum vessel is 3. 47mm , while the displacement of the LHCD antenna system is 0.9mm,at the maximal vacuum vessel temperature 112 ℃. From this displacement , the stress on the LHCD system was calculated. Analyzing the effect on the LHCD system by the baking , the possible means for LHCD transmission system to mitigate it are put forward.

Structural modification and power flux analysis of HL-2A divertor

JIANG Jing, RAN Hong, LIU De-quan, CHENG Fa-yin, BAI Gang-yi

2006, 26(1):  22-26. 

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An adoptable divertor structure and its cooling manner are designed with optimal parameters for HL-2A divertor according to its primary modification scheme.Double shear splice joints on the private flux target plates and outer target plates,and poloidal water flows in toroidal manifolds are chosen.The result given by finite element analysis of the divertor system shows that the sustainable power flux of target plates are higher while reducing the cooling flow requirements.

Performance of the LHCD low-voltage real-time protection system on HL-2A tokamak

LI Xiu-juan, WANG Ming-wei, SONG Shao-dong, KANG Zi-hua

2006, 26(1):  27-30. 

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The principle and operation of the low-voltage real-time protection system for the lower hybrid current drive (LHCD) system on HL-2A tokamak has been presented. The real-time protection is carried out by hardware circuits which must be reliable with response time less than 1μs. The real-time protection for wave guide arcing protection, klystron body-current protection and over-current protection of klystron collector had been realized in the LHCD experiments using single klystron in 2004. Special detector for each protected target was used . The precision of body-current detector reaches 0. 7 %. The protection system works reliably.

Protection and experimental analysis of the first mirror in infrared laser diagnostic on HL-2A tokamak

GAO Bing-yi, ZHOU Yan, DENG Zhong-chao, YI Jiang, TANG Yi-wu, DING Xuan-tong

2006, 26(1):  31-34. 

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The sputtering and deposition experiments for the first mirror of the infrared laser diagnostic were described. The reflectivities of the first mirror before and after the experiments were compared. Impurity components on the first mirror surface after experiments were also given. Protection of the first mirror with facing plate is suggested.

Analytic fitting of transport coefficients in the electron conductivity model for dense plasma

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

2006, 26(1):  35-41. 

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A complete set of transport coefficients with reasonable accuracy in a wide range of plasma temperatures and densities. Therefore , they are useful for numerical simulation in magnetic confinement fusion , laser fusion , and Z  pinch plasma , etc. The analytic fitting of transport coefficients in a variety of conditions are given in this paper. The formulas can facilitate the calculation of transport coefficients for various applications.

Theoretical calculation of mean opacity of gold mixtures

YAN An-ying, JIANG Ming, CHENG Xin-lu, YANG Xiang-dong

2006, 26(1):  42-46. 

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A screened hydrogenic model with l splitting is proposed to calculate the the Rosseland mean opacities for some high-Z pure elements of Au、Ho、 Gd、Sm、Nd、Sn、Ag , and mixtures of Au at high temperature ( T= 200～ 300eV) and high density ( ρ = 1g ·cm^-3) . The results are in good agreement with the calculations of DCA/ UTA and STA models.

Development of a data analysis and visualization software for the HT-7 tokamak experiment

Qu Lian-zheng, YU Wen-yong, LUO Jia-rong, ZHU Lin

2006, 26(1):  47-53. 

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Modeling , design and implementation of a data analysis and visualization software for the HT-7 tokamak based on UML, an important tool of object-oriented system modeling and used in the whole system life cycle, is given. The software adopts key technologies such as Active X to get data from server,Matlab engine to calculate expression of signals and OpenGL to realize three-dimensional showing from array signals.This software was favorable stabilization and  functional agility during the experiment in the spring of 2004.User can easily carry on the data analysis and visualization by using mouse only and the showing can be scaled and rotated by interactive manner.

Design and numerical simulation of the electromagnetic field of linear anode layer ion source

WANG Li-sheng, TANG De-li, CHENG Chang-ming

2006, 26(1):  54-58. 

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The principle of anode layer ion source for etching , pre-cleaning and ion beam assisted deposition was described. The influence of the magnetic field on the performance of anode layer ion source was analyzed. Design of the magnetic loop for the linear anode layer ion source was given. The electromagnetic field distribution of the ion source was simulated by means of ANSYS code and the simulation results were in agreement with experimental ones. The numerical simulation results of the electromagnetic field are useful for improving the anode layer ion source.

Study of gliding arc discharge plasma

YANG Chi, LIN Lie, WU Bin

2006, 26(1):  59-65. 

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The electric parameters change during discharge is studied and the relationship between non-equilibrium degree and parameters is discussed for gliding arc discharges. Using two-channel model , the rules of arc moving due to effect of the airflow is simulated. The numerical simulation results can help analyzing the generation mechanism of gliding arc non-equilibrium plasma.

Design of metrical system for magnet and thermal shield in EAST

LIN Feng-mei, WU Song-tao, LIU Quan-kun, CHENG Dao-lin, ZHANG Yuan-bin, LIU Chang-le

2006, 26(1):  66-70. 

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The deformation and displacement of magnet and thermal shield will take place due to the temperature change during EAST operating. In order to measure the displacement , an extended arm is used to transfer it to a place where it is easy to be measuret and the variation of displacement is changed to voltage data by rheostat , finally the displacment data is obtained from voltage data. This system mainly focused on how to measure the displacement of magnet and thermal shield in EAST.

Fitted expression of Child-Langmuir law for planar direct-current biased negative voltage collision sheaths

QIAN Dan-na, LI Xue-chun, WANG You-nian

2006, 26(1):  71-74. 

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With the hydrodynamic model , effects of the charge-exchange collisions between ions and neutrals on the direct-current biased voltage sheaths is studied. For planar target , the sheath thickness becomes smaller as collision parameter increases. A fitted expression of the Child-Langmiur law for the planar sheath is presented based on the numerical results. In addition , the influence of the target radius on the sheath thickness is also studied for the cylindrical and spherical targets , respectively.

The biological effect of arc discharge plasma combined with gradual magnetic field on tomato seeds

YIN Mei-qiang, MA Teng-cai, HUANG Ming-jing, MA Bu-zhou

2006, 26(1):  75-80. 

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Using arc discharge plasma combined with gradual magnetic field to treat seeds is a new plasma biological technology. The biological effect and drought resistance of tomato seeds treated with different plasma parameters were compared. The increasing of proline content indicates that the drought resistance of tomato seedlings could be increased due to reduction of penetration potential of plant cell. Increased SOD , POD activity , root activity and ATP content show that water stress could be alleviated by eliminating the free radicle and increasing metabolism.