Table of Content

15 June 2006, Volume 26 Issue 2

Previous Issue    Next Issue

Contents

Edge plasma characteristics of divertor configuration in HL-2A tokamak

HONG Wen-yu, YAN Long-wen, QIAN Jun, PAN Yu-dong, LUO Cui-wen, XU Zheng-yu, PAN Li, YANG Qing-wei, HUANG Yuan

2006, 26(2):  81-86. 

Asbtract ( )   PDF (3190KB) ( )  

References | Related Articles | Metrics

Edge plasma temperature, density, poloidal electric field, radial electric field, Reynolds stress, poloidal rotation velocities and their profiles have been obtained using a movable array of Mach/Reynolds stress/Langmuir 10-probes and reciprocating fast scanning 4-probes in plasma discharges. Measurement results are used to analyze plasma confinement, fluctuations and their correlation. The fixed flush 3-probe arrays, mounted on the 4 divertor neutralization plates at the same toroidal cross-section in divertor chamber, are used to measure the profiles of the electron temperature, density and float potential. The profiles and decay lengths of energy or particle flow can be estimated from plasma temperature and density. Edge plasma behaviors between limiter and divertor configuration are compared. Edge characteristics are analyzed in discharges with supersonic molecular beam injection and lower hybrid current drive respectively. The dependence of the radial gradient of Reynolds stress on poloidal flow and the radial gradient of electric field on turbulent loss is discussed.

Effects of compressibility on the Rayleigh-Taylor instability in Z-pinch implosions

HUANG Lin, JIAN Guang-de

2006, 26(2):  87-94. 

Asbtract ( )   PDF (634KB) ( )  

References | Related Articles | Metrics

The effects of compressibility on the Rayleigh-Taylor instability in Z-pinch implosion plasmas are investigated by means of simple slab geometry. The linear mode equation, which includes main steady-state quantities and their gradients, is derived. Numerical solutions are presented. The incompressible fluid result is also obtained. These results indicate that the linear growth rate of the Rayleigh-Taylor instability for the compressible magnetohydrodynamic fluid is far larger than one in the incompressible situation. Therefore, the compressible systems are all more unstable than the incompressible ones.

Analysis of LHCD vacuum system on HL-2A tokamak

RAO Jun, CAO Zeng, CHEN Gang-yu, ZENG Jian-er, LEI Jian-xin, ZHANG Jin-song

2006, 26(2):  95-99. 

Asbtract ( )   PDF (1031KB) ( )  

References | Related Articles | Metrics

The engineering test of 1MW LHCD system has been carried out using one klystron. The LHCD system vacuum pumping had been set up for the transmission line and launch antenna. The vacuum in antenna and transmission are 2.3 Pa and 4.3×10² Pa respectively, and the leakage factor is 1.675×10^-4 Pa•m³•s^-1 between antenna and tokamak. To improve capability of transmission power and avoid arcing in wave guide, gas is filled in the space between antenna and Tokamak. Vacuum characteristics of the LHCD system and its influence on the vacuum of HL-2A tokamak are studied preliminary.

Prediction of equivalent modulus of superconducting busbar for ITER

WANG Jian-qing，WU Song-tao，SONG Yun-tao，ZHANG Yuan-bin

2006, 26(2):  100-103. 

Asbtract ( )   PDF (353KB) ( )  

References | Related Articles | Metrics

The superconducting busbar of the ITER superconducting magnets is of composite structure consisted of NbTi cable-in-conduit conductor, insulation layers and grounding metal net. The equivalent modulus of the superconducting busbar have been calculated based on the conventional composite theory and the method combining the homogenization theory with the composite damage theory, respectively. These results are necessary for analyzing and calculating the stress ,deformation and the thermal behavior of the superconductor busbar.

EAST PFCs baking system design and control solution

WAN Xiao-gang, YAO Da-mao, WANG Jian, LI Ying-bin

2006, 26(2):  105-109. 

Asbtract ( )   PDF (2695KB) ( )  

References | Related Articles | Metrics

A kind of gas flow vacuum baking technique is adopted in EAST PFCs. This baking system is designed, and a scenario of process control and remote supervision is presented.

Numerical simulation of MHD effect of liquid metal free surface jet flows

KANG Wei-shan, XU Zeng-yu, PAN Chuan-jie

2006, 26(2):  110-114. 

Asbtract ( )   PDF (1402KB) ( )  

References | Related Articles | Metrics

The MHD effect on liquid metal free surface jet flows under magnetic field has been investigated. The stability of the jet flows under strong magnetic field was explained with its velocity, induced potential and current. The numerical results are in agreement with the analysis ones.

Design of microwave reflectometor on HL-2A tokamak

YANG Zhou-jun, DING Xuan-tong, LIU Ze-tian, XIAO Wei-wen, SHI Zhong-bing, LI Ying-liang, Vladimir Zhuravlev

2006, 26(2):  115-120. 

Asbtract ( )   PDF (3257KB) ( )  

References | Related Articles | Metrics

Two amplitude modulation microwave reflectometry systems based on time-delay method with scanning microwave source are designed for plasma density profile measurement on HL-2A tokamak. These two microwave reflectometors have different frequency ranges (26.5~40GHz, 40~60GHz) and they are suitable for measuring the plasma density (0.84～1.98)×10¹⁹m^-3 and (1.98～4.47)×10¹⁹m^-3 respectively. Temporal resolution is 1ms and spatial resolution is about 5mm.

Determination of plasma displacement by flux loops on HL-2A tokamak

ZHOU Hang-yu, YANG Qing-wei, FENG Bei-bin, SONG Xian-ming, ZHENG Yin-jia, LI Bo, ZHANG Jin-hua, JI Xiao-quan, YUAN Bao-shan

2006, 26(2):  121-127. 

Asbtract ( )   PDF (3056KB) ( )  

References | Related Articles | Metrics

The principle of determination of plasma displacement by flux loops is given in detail. Evolution of plasma displacement is given by calculation using data obtained by flux loops and its nearby pick-up coils. The plasma displacement waveforms are compared with results from non-symmetric probe and CCD images. The results are in agreement accurately. This method is applied to the HL-2A plasma displacement feedback control system.

Numerical solution of transport coefficients for magnetized plasma

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

2006, 26(2):  128-134. 

Asbtract ( )   PDF (1735KB) ( )  

References | Related Articles | Metrics

An electron conductivity model for dense plasma is utilized to calculate a complete set of transport coefficients in plasma. These coefficients, applying to partially ionized and partially degenerated plasmas with arbitrary compositions, are reasonably accurate in a wide range of plasma temperature and density. They can be used in the simulations of magnetic confinement fusion, laser fusion, and Z-pinch plasma, etc.

Monte Carlo simulation of ions in nitrogen hollow cathode glow discharge plasma

ZHANG Lian-zhu, FU Feng-qing, WANG Zeng-bo, LIU Jun-hong

2006, 26(2):  135-139. 

Asbtract ( )   PDF (1298KB) ( )  

References | Related Articles | Metrics

The ions (N₂⁺, N⁺) transport process in cathode sheath of nitrogen cylinder hollow cathode discharge plasma is studied using Monte Carlo simulation. Energy distribution and angular distribution of ions (N₂⁺, N⁺) in cathode sheath are calculated, and their variation behaviors with the discharge parameters are investigated. Results are compared with ones of the parallel flat electrode N₂ dc glow discharge under the corresponding conditions. It is shown that the nitrogen cylinder hollow cathode discharge will be beneficial to the production of the nitrogen ions.

Moving method for solving the 3D three-temperature radiation fluid dynamics equations

HUANG Wei, CHANG Wen-wei, MA Yan-yun

2006, 26(2):  140-145. 

Asbtract ( )   PDF (1226KB) ( )  

References | Related Articles | Metrics

The moving method is put forward for solving the 3D three-temperature radiation fluid dynamics equations which normally are difficult computation with 3D cells due to complicated behavior of the plasma flow. An improved evident algorithm is used to solve the three-temperature energy equation. The satisfied calculation results have been obtained.

Glow discharge characteristics of four anodes device

YUAN Zhong-cai, SHI Jia-ming, XU Bo

2006, 26(2):  146-150. 

Asbtract ( )   PDF (2352KB) ( )  

References | Related Articles | Metrics

The dependences of the characteristic of normal glow current-voltage, and the irradiance identity on the helium gas pressure in the glassy tube of the four anodes DC device were measured and analyzed. The results show that glow discharge can be realized in larger range of gas pressure and electric current with the constant-current mode than with the constant-voltage mode. The helium stable discharge can take place in the pressure range from 1Pa to 800Pa, and in the current up to about 500mA. With the change of the bright spots on the surface of electrodes, the discharge voltage at low current region almost increases exponentially with the current in a certain pressure. The growth of the voltage becomes slower with current increase. Due to increase of collision frequency, the voltage increase speed with the current gets slowly for high gas pressure. The analyzed results indicate that it is abnormal glow discharge. From the irradiance picture obtained with CCD, the plasma shrinking towards the cathode with the pressure increase was observed.

Power system for diagnostic neutral beam and study on the experiment of neutral beam extraction

ZHANG Jian, LIU Bao-hua, HU Li-qun, DU Shao-wu, HT-7DNBZu

2006, 26(2):  151-155. 

Asbtract ( )   PDF (578KB) ( )  

References | Related Articles | Metrics

Control system of power supply for HT-7 diagnostic neutral beam source was composed of PLC, timer and master control logic. The experimental results show the good facility and reliability. The arcing and beam extraction are studied experimentally. The influences on the beam current are observed by adjusting arc voltage and gas injection at different cases. The neutral beam power of 50kW and beam current about 3.6A were obtained in this operation priod with 35kV HV and 80A arc current.

Electrical characteristic simulation of plasma flow control system

SONG Hui-min, LI Ying-hong, WU Yun, ZHANG Pu

2006, 26(2):  156-160. 

Asbtract ( )   PDF (321KB) ( )  

References | Related Articles | Metrics

The electrical characteristic simulation of plasma flow control system was carried out using Pspice code. By consideration of modeled plasma discharge as a subsection-nonlinear voltage controlled current source, the key problem of simulating the electrical characteristic of plasma flow control system was reduced. On the basis of the plasma discharge model, the electrical characteristic of the plasma flow control system was numerically simulated. Simulation results verify that the plasma discharge model established is useful for further simulation and design improvement of actual control system.