Table of Content

15 March 2007, Volume 27 Issue 1

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Research Report

Analysis and calculation of ray tracing and wave power deposit profiles of electron cyclotron resonance heating in the HL-2A tokamak

SHI Bing-ren，SHI Ying-tian

2007, 27(1):  1-6. 

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With the single-null divertor configuration on the HL-2A tokamak, the ray tracing and the wave power deposit for the ordinary electron cyclotron wave, perpendicularly injected from the weak field side, are analyzed. For on-axis resonance, it is necessary to determine a physical scale length to treat adequately the wave power deposit profile. The effective absorption layer of a single ray can be used as such physical scale length to obtain a formula for the wave power deposit. As examples, results of wave power deposit profiles for on-axis heating are reported for both cases of the magnetic axis locate on and depart from the equatorial plane.

Experimental observation of divertor configuration and ECRH on the HL-2A tokamak

HONG Wen-yu, YAN Long-wen, QIAN Jun, ZHAO Kai-jun, CHENG Jun, LUO Cui-wen, XU Zheng-yu

2007, 27(1):  7-12. 

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The divertor plasma characteristics are studied by means of electro-motion scanning 4-probes in the outer divertor chamber and the fixed flush probe arrays on the 4 divertor neutralization plates at the same toroidal cross-section in the HL-2A tokamak. They provide important parameters for investigation of distribution and asymmetric of plasma parameter in the divertor. The profiles of energy or particle flow and their decay lengths can be estimated by the target temperature and density. They are very useful to investigate plasma behavior and physical characteristic in the divertor mode. These results identify that divertor can improve the particle confinement.

Electromagnetic force analysis of ICRF heating antenna on EAST tokamak

YANG Qing-xi, SONG Yun-tao, WU Song-tao

2007, 27(1):  12-17. 

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With the physical operating parameters of EAST tokamak, the formula of the inductive current and electromagnetic load on the ICRF heating antenna and the curve diagram depending on the time of plasma disruption is given. Finally, the further discussion on the utmost case of the electromagnetic force and its effect on the antenna structure using the curve diagram was given.

Study of opacity for inertia elements mixture

JIANG Ming, ZHOU Ping, WANG Cai-xia

2007, 27(1):  17-21. 

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The frequency-dependent opacities and the Rosseland mean opacity for mixture of inertia elements Ar, Kr, Xe are studied using the l splitting screened hydrogenic model. The relation of the Rosseland mean opacity for inertia elements mixture to the mixture specifications, mixed proportion in densety range of 0.5~2g·cm⁻³ and temperature range of 100~250eV are investigated. The results indicate that Rosseland mean opacity is enhanced significantly for mixture of Xe-Ar and Xe-Kr but not increased for mixture of Ar-Kr. The comparison of the frequency-dependent opacities of pure inertia element absorption peaks and valleys, we account the reason for enhancement or reduction in the Rosseland mean opacity for mixed inertia elements, and the optimal mixed proportion to obtain the maximal mean opacity for inertia element mixture.

Measurement of radial profiles for the edge plasma parameters in the HL-2A tokamak

CHENG Jun, YAN Long-wen, HONG Wen-yu, QIAN Jun, ZHAO Kai-jun

2007, 27(1):  22-27. 

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Fast reciprocating probe system on the HL-2A tokamak is described in detail, which can radially scan the edge plasma within 8cm from outboard midplane. This system consists of the high pressure gas-source, transmission bar, digital grating displacement measurement system and probe head assembly. The plasma parameter profiles measured include electron temperature and density as well as their decay lengths, floating potential, space potential, saturation ion current and particle flux in a discharge with this system. These results are consistent with those from other tokamaks, such as JT-60U, TEXT, HT-7 and so on.

Design of the quench protection system of the EAST PFPS and its simulation

SONG Zhi-Quan, FU Feng, SHANG Lun-Jun, TUN Xi-Bing

2007, 27(1):  28-33. 

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The design schemes of the quench protection system of the EAST poloidal field power supply (PFPS) are given. The detailed descriptions of structure of two stages commutating current and its operated principle are introduced, which are applied to two quench protection breakers——the direct current circuit breaker (DCCB) and the explosively operated circuit breaker (EOCB). The regulation of the commutating current of the structure is analyzed，the structure resolves the problem of large current interruption effectively. The simulation results show that the quench protection system meets the requirements of design.

Development of super-synchronization speed control assembly for 2500kW double-fed motor

LI Hua-jun, DU Cang, XUAN Wei-min, PENG Jian-fei, HU Hao-tian, LIU Ling, WANG Shu-jin, KANG Li, XU Li-rong, HUANG Zhao-rong, WANG Xiao-ping

2007, 27(1):  34-38. 

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The super-synchronization speed control assemblies for the two 2500kW induction motors have been developed successfully in order to meet the need for toroidal field increasing in HL-2A tokamak. Based on the a.c./a.c. cycloconverter, the speed of each 2500kW motor has been regulated by means of vector control technology for double-fed motor. The highest rotate speed of the two 80MVA generator sets have been increased from 1488rpm rated speed to 1650rpm and the released energy of each generator set in one pulse discharge can reach 500MJ. Therefore the toroidal field system is able to reach 2.8T for experiment.

Simulation of double-fed speed regulation system for 125MVA motor-generator set

2007, 27(1):  39-43. 

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A simulation modeling of double-fed motor speed regulation for 125MVA AC pulsed M-G set of HL-2A is built using Matlab. Some parameters of the project are obtained by the pre-simulation, and the process of start-up is analyzed. In the Matlab simulation the motor model in Simulink can not be connected directly to the cycloconverter model. This problem is solved by adding an ideal transformer model between them, and the satisfactory result is obtained. A new method of control switching two cycloconverter without circulating current has been introduced.

Development of the fast arcing protection for ECRH system on the HL-2A tokamak

LI Xiu-juan，RAO Jun，WANG Ming-wei，WANG Xue-yun，LI Bo

2007, 27(1):  44-47. 

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The fast arcing protection of the electron cyclotron resonance heating (ECRH) is very important in the heating experiment of the HL-2A tokamak. ECRH has the ability of 1MW using two gyrotrons (each about 500kW). The states of the protected objects must been detect then deal with effectively arcing-events in order to accomplish the protection function. The fast arcing protection includes two parts such as some arcing detectors and one arcing protector for the one gyrotron and one waveguide line. The ECRH arcing protection system must be fast enough and very reliable, and the total response time is less than 25μs.

Design of a new ceramic window in 3.7GHz LHCD transmission system

LIU Liang, SHAN Jia-fang, LIU Fu-kun, KUANG Guang-li

2007, 27(1):  48-51. 

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According to the theory of ceramic window design, using electromagnetic field simulator, CST, and finite element method analysis software, ANSYS, the electromagnetic and thermal performances of LHCD new ceramic window have been calculated and simulated. BeO is used as windows body material for its high conductivity. Within the bandwidth of more than 300MHz, the stationary wave ratio is below 1.1, and the maximum temperature rising is 11.7?C on the center of the ceramic window.

Data processing upgrade in lower hybrid system on EAST tokamak

WANG Dong-xia, JIANG Min, SHAN Jia-fang

2007, 27(1):  53-57. 

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The method based on the double buffering for interruption acquisition, the separate store for files and the data display with file mergence is proposed to satisfy data collection, store and display after data increase greatly in EAST discharges with lower hybrid heating.

High power microwave test system and application on klystrons

WANG Mao, LIU Liang, WANG Xiao-ji, XU Chan-dong, JIANG Min, ZHAO Lian-min, LIU Fu-kun, SHAN Jia-fang, KUANG Guang-li, Pugnin V, Khimchenko A, Lindmila N

2007, 27(1):  57-61. 

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In order to test the microwave instruments of LHCD system, a high power (up to 100kW，continuous wave mode) microwave test system is established. Components of the high power microwave test system, the operating principle of this system and the test results of the klystrons have been presented in the paper.

Mechanism of plasma plume produced by laser ablation of metal Cu at different ambient pressures

HUANG Qiang-ju

2007, 27(1):  62-66. 

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Spectra of metal Cu ablation by XeCl excimer laser have been measured in hydrogen atmosphere using time-space-resolved technique. The photographs of optical plume from XeCl excimer laser ablation of metal Cu particle in different hydrogen pressure have been taken. The experimental results show that plume has different colour in different range, and varies with hydrogen gas pressure. The size of plume area decreases and plume colour is getting lighter with ambient gas pressure increase. The detailed mechanism of species particle excition is discussed. The experimental results are qualitatively explained with the mechanism.

Investigation of utilization ratio and calculating method of familiar magnetron sputtering targets

ZHAO Jia-xue, JIN Fan-y

2007, 27(1):  66-73. 

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Theoretical calculation methods of utilization ratio of three familiar magnetron-sputtering targets are investigated. Approximate computation formula is deduced. Factors influencing utilization ratios are analyzed. Safe surplus thickness affects the utilization ratio of all the three type targets. A term of shrinkage coefficient is introduced in the two former formulas. According to the calculated results from the measured data and theoretical formulas, an approximate conclusion can be made: generally, utilization ratio of a circular planar target is lower than 10%, one of a rectangular planar target is about 20%~30%, both strongly affected by shrinkage coefficient, and one of a rotary cylindrical target can reach 50%, hardly over 70%.

Design of antenna for RF inductively coupled plasma ion beam source

SU Zhi-wei, CHEN Qing-chuan, HAN Da-kai

2007, 27(1):  73-77. 

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To obtain more uniform beam, three types of antennas of the inductively coupled plasma ion beam source applied to the etching have been designed. The electric field distributions excited by these antennas were calculated and compared. The results show that the linear non-equidistant antenna and the parallel multi-spiral antenna are capable of generating fairly uniform electric field distributions with comparatively higher coupling efficiency.

Study on out-gassing by baking and glow discharge during wall conditioning of vacuum chamber

WANG Zhi-wen, WEI Wei-xing, ZHAO Yuan-qing, HE Yan-he, LIAO Yi-kui

2007, 27(1):  77-80. 

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The model of out-gassing by baking and glow discharge cleaning (GDC) is set up. The properties of them are studied. Out-gassing by baking is from bulk and it obeys the diffusion equation. Out-gassing of glow discharge cleaning is mainly on surface, it is inducement out-gassing by sputtering. Thus the properties of out-gassing for baking and GDC on the HL-1M tokamak are analyzed. Some empirical formulas are given.