Table of Content

15 September 2008, Volume 28 Issue 3

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Plasma Physics

Experimental system of measuring density profile with multi-channel interferometer on the HL-2A tokamak

DENG Zhong-chao, ZHOU Yan, YI Jiang, LI Yong-gao, LI Lian-cai, LIU Ze-tian

2008, 28(3):  193-198. 

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To measure the electron density profile, a new system of the multi-channel FIR laser interferometer has been designed and set up on HL-2A tokamak (with divertor configuration). A series of dielectric wave-guides are employed in the arrangement of long distance optic path and a high power HCN laser with six-meter cavity has been developed, in addition, the lock-in loop filter with FPGA technology has been adopted to reduce the disturb effect. The phase-comparison methods of software and hardware are simultaneously used to monitor the electron density and to display the density evolution timely. The accuracy of the multi-channel interferometer is closed to 1/33 fringe, the corresponding density is 1.3×10¹¹cm^-3, and the time resolution is 0.1ms.

EM scattering analysis of the laser plasma channel antenna

XIA Xin-ren, YIN Cheng-you

2008, 28(3):  199-204. 

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The laser plasma channel antenna is equivalent to uniform cold magnetized plasma beam, which is assumed to be gyrating transversely and drifting longitudinally. The cross-section of the plasma beam is considered as circle and the shape is not changeable along with axis. Taking into account the influence of inertia force such as centrifugal force and Coriolis force etc, the EM scattering field of laser plasma channel antenna is derived from Maxwell equations and constitutive relations, and then an example is calculated and some interesting phenomena are discovered.

A simplified theoretical study on MHD flow with FCI in liquid metal blanket system

XU Zeng-yu, PAN Chuan-jie, ZHANG Xiu-jie

2008, 28(3):  205-208. 

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Based on the previous MHD duct flow experiments, the law of mass conservation, the law of charge conservation and the Lorentz force as well as the principle of equivalent circuit, a simplified theoretical method to analysis MHD effect of duct with FCI is developed. The result shows that FCI can reduce MHD pressure drop efficiently; there is a critical electric-conductivity that when the FCI electric-conductivity is higher than this value the velocity in the core region will be lower than that at the boundary; there is also an optimized parameter-combination of duct geometry, FCI electric-conductivity and liquid-metal material for the MHD pressure drop reduced efficiently.

Diagnoses of electron heating on HT-7 tokamak by soft X-ray spectra

XU Ping, LIN Shi-yao, HU Li-qun, DUAN Yan-min, SHI Yue-jiang, HT-7 experimental

2008, 28(3):  209-212. 

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The diagnostic system of soft X-ray spectra is introduced, and the electron temperature on HT-7 tokamak has been measured by this system. Remarkable increase of the electron temperatures has been observed in the experiments of plasma heating by ion Bernstein waves in collaboration with lower hybrid waves.

Nuclear Fusion Engineering and Technology

Structure improvement and numerical simulation for TBM sub-module coolant flow distribution

HAO Teng-fei, FENG Kai-ming, ZHAO Zhou, YUAN Tao

2008, 28(3):  213-217. 

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Three-dimensional flow distribution in the CH HCSB TBM was numerical simulated using the fluid dynamic code FLUENT. The result shows that the uneven distribution of helium flows in the original sub-module cooling tubes lead the heat transfer efficiency falls. Therefore, the design improvement on the flow distribution of sub-module is necessary.

Design and heat load analysis of support structure of CR superconducting dipole magnet for FAIR

ZHU Yin-feng, WU Song-tao, WU Wei-yue, XU Hou-chang, LIU Chang-le

2008, 28(3):  218-222. 

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In order to meet the requirement of the Collector ring (CR) dipole superconducting magnet of FAIR in the process of operation, meanwhile, and to ensure the heat loads coming from the support structures to be lower than the design demands, the 3D models of support structures have been constructed with CATIA, then the calculation of low-temperature heat-load and the structure analysis have been done with ANSYS, the support structure material, 316LN+G10, is decided according to the heat-load calculation and the structure optimization, these results are necessary for manufacturing the formal magnet.

Activation calculation and analysis for Chinese ITER solid test blanket module

WANG Qi-jie, FENG Kai-ming, CHEN Zhi

2008, 28(3):  223-227. 

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An analysis model has been constructed according to the geometrical arrangement and the material composition of CH HCSB TBM. The codes of BISON, FDKR and the decay chain data library AF-DCDLIB are used to calculate the radioactivity, afterheat decay, BHP (biological hazard potential) and the dose rate from activation products of HCSB TBM. The calculation results show that after a continuous operation over 1 years with 500MW fusion power the total radioactivity, heat decay and BHP are 4.587×10¹⁵Bq, 9.009×10^-3MW and 90.73 km³•kW^-1 respectively, and the dose rate on the back plate is 3.278×105mSv•h^-1. It means that there is no serious environmental safety issue during the TBM operation.

Electromagnetic safety analysis on Chinese ITER HCSB-TBM design

CHEN Yan-jing, FENG Kai-ming, GAO Chun-ming, CHENG Guang-zhao, ZHANG Guo-shu, QIU Sui-zheng

2008, 28(3):  228-232. 

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An electromagnetic safety analysis for optimizing ITER HCSB-TBM design is performed by using ANSYS code under the ITER operation condition. The calculation results show that the HCSB TBM design have reasonable margin from the perspective of the electromagnetic safety.

Method on the critical current test of NbTi superconducting strand for ITER

LIU Fang, WENG Pei-de, WU Yu, SHI Yi, LONG Feng

2008, 28(3):  233-237. 

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The method and device for the critical current test of NbTi superconducting strand in different temperature are introduced, which mainly contains a background field system and a variable cryostat system. The background field is supplied by a superconducting magnet with a Ø70mm warm bore, in which the current leads are designed to satisfy the NbTi critical current test and the superconducting magnet could produce fields up to 16T. The strand critical current in different field and different temperature has been acquired by this system, the result is fitted with the “Luca” law, and then the performance of the strand can be evaluated integrally.

J-TEXT tokamak toroidal field power supply system and its commissioning

ZHANG Ming, ZHUANG Ge, YU Ke-xun, QIU Sheng-shun, YANG Cheng

2008, 28(3):  238-241. 

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The toroidal field (TF) magnet of J-TEXT tokamak consists of 16 near-round copper coils interlinked in series. The power supply system for TF coils is required to provide 500ms, 160kA flat current in order to produce a maximum magnetic field of 3T in the plasma centre. Based on the pre-existed TEXT-U TF power supply system, a new control and protection system is re-designed and modified, and the re-built system can provide a flat current up to 92.5kA and can create a toroidal field up to 1.74T in the primary campaign.

Design of transmission line of ICRH antenna for EAST

YANG Qing-xi, SONG Yun-tao, WU Song-tao, CHEN Yong-hua

2008, 28(3):  242-246. 

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The design of transmission line of ICRH antenna for EAST was expounded and the stress analysis was carried out using FEA (finite element analysis) technique. The bellow thickness and the support structure for the inner conductor of transmission line were optimized by ANSYS; then the power loss, the thermal structural deformation, VSWR and the maximum power capability of transmission line were calculated; and finally the feasibility of transmission line was confirmed.

Optimal analysis for the compact fusion-fission hybrid reactor parameters and discharge simulation

CHEN Mei-xia1, 2, WU Bin1, ZHOU Xiao-lin2, LIU Cheng-yue1

2008, 28(3):  247-251. 

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Under the conditions of constant major-radius and minor-radius, an optimal analysis for the parameters of the compact fusion-fission hybrid reactor, including the size of the center solenoid, has been made by using the fusion system analysis code, and the final optimal design point has been found out. Based on this design point, the discharge simulation of the reactor is performed with the tokamak simulation code (TSC), and the modeling results show that the reactor is more economic and feasible.

Development of DC active filter for high magnetic field stable power supply

WANG Lei, LIU Xiao-ning

2008, 28(3):  252-256. 

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The DC active filter (DAF), with very low current ripple, of the stable power supply system of high magnetic field device is developed by using the PWM and parallel active power filter technique. Due to the PWM control technique, the required DAF current can be obtained and the current ripple can be compensated by means of monitoring the load voltage, and the current ripple becomes very low by adjusting the load voltage. The simulation and analysis show that this system can respond to the reference quickly and is effective in suppressing the harmonics, especially the low-order harmonics. The feasibility of the proposed scheme is proved on the equipment built in the laboratory.

Non-Fusion Plasma Applications

ICCD image analysis of a novel large area dispersed arc plasma source

ZHOU He-ling, XIA Wei-dong, LI Lin-cun, ZHOU Zhi-peng, BAI Bing, CHENG Liang

2008, 28(3):  265-269. 

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Unsaturated images of large area dispersed argon plasma are captured by an intensified charge-coupled device (ICCD) equipped with a narrow-band interference filter. The experimental results show that the strong electromagnetic force disperses the arc until the plasma cloud fills the axial cross-section of the chamber as the injected current increases, the plasma is uniformly-distributed when the arc is fully dispersed, the arc moves more steadily and smoothly with the significantly-reduced voltage fluctuation, and the phenomena of multi cathode roots and diffused cathode roots generally correspond to a dispersed arc.

Microwave resonator probe and its application in plasma diagnosing

MA Liu, SHI Jia-ming, YUAN Zhong-cai, CHEN Zong-sheng, HUANG Yong

2008, 28(3):  270-273. 

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The microwave resonator probe (hairpin resonator probe), which can be used to measure the electron density of steady and time-resolved plasma, together with the working principle and application of this probe are presented. The process of transmission mode and reflection mode, as well as the effects on measurement range, test precision and the space-resolving capability are analyzed and investigated. It reveals that a longer probe will be efficiency to enhance the test precision and to broaden the measurement range, and choosing the microwave-sweeping source with higher frequency and higher resolving capability will be of the same function. The theoretical analysis shows that the electron density diagnosed by this probe is about 1.37×10⁸~4.1×10¹¹cm^-3.

Polymers preparation under methane plasma environment

YANG Wu-bao1, CAI Ze-yong1, ZHAO Zhen2, QI Lu3

2008, 28(3):  274-277. 

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Polymers are prepared under methane plasma environment, and appear to be white, slightly yellow, soft thread-like powders and floc under optical microscope. The polymers contain –CH3, -CH2, C-O, -C=C-, -OH etc. functional groups, but no simplex carbons. It is found that the solubility of this polymer is less than 0.1mg.ml^-1 in different organic solvent. The productivity of the polymers is higher under a plasma environment with higher ionization, higher polarization of neutral gas, lower environment temperature and less permittivity.

Analysis and comparison of numerical simulation methods of low temperature plasma

YUAN Zhong-cai, SHI Jia-ming, HUANG Yong, MA Liu

2008, 28(3):  278-284. 

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Fluid model, kinetic (particle-in-cell/Monte Carlo collision) model (PIC/MCC), kinetic-fluid hybrid simulation model, and the external circuit simulation method are adopted to simulate the low temperature plasma behavior and are compared with each other, the principle and adaptability of each method are also explored and discussed. The PIC/MCC model is exploited to study the characteristics of the glow discharge plasmas in a device with four anodes, and the influence of an external mirror magnetic field on radial electron density distribution is analyzed.

Visible framing camera and its application in Z pinch diagnostics

SHENG Liang, WEI Fu-li, QIU Meng-tong, HEI Dong-wei, WANG Kui-lu,

2008, 28(3):  285-288. 

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A nanosecond visible framing camera is developed to study the early stage of the wire-array Z pinch machine called “Qiang Guang-I”, and the plasma images of the Z pinch machine are acquired by using this camera. The main performances of this camera are presented and the results are discussed.