Nuclear Fusion and Plasma Physics

Inductance calculation of the toroidal field coils in the HL-2M tokamak

YUAN Bao-shan, SONG Xian-ming, JI Xiao-quan

2007, 27(4): 273-276.

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A concise method to calculate the inductance of the TF (toroidal field) coils in the HL-2M tokamak is presented. To simplify the calculation, the TF coils are simulated using the polygon current filaments and the multiple integral is replaced by the inductance summation of two small beeline segments. The inductance of the TF coils has been calculated by using the plasma discharge data of the HL-2A tokamak, and the results show that the method is valid.

Development of 1MW ECRH transmission system in the HL-2A tokamak

ZHOU Jun, CHEN Gang-yu, ZHANG Jing-song, RAO Jun,

2007, 27(4): 277-279.

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The transmission system of 1MW/68GHz/1s ECRH for the HL-2A tokamak includes two transmission lines. Each line consists of corrugated waveguide, miter bends and a DC break, in which the HE₁₁ mode waves propagate with low loss and high mode purity. In order to align the lines, laser was used firstly and then the mode distribution of short pulse wave was measured by means of thermo-paper. The tilt angle is less than 0.0054rad.

Numerical simulation of ohmic discharge in the EAST tokamak

LIU Cheng-yue1, 2 , XIAO Bing-jia1, WU Bin1, LIU Lian-zhong1, LUO Zheng-ping1

2007, 27(4): 280-285.

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The first ohmic discharge in the EAST experiment is simulated using the famous11/2-D equilibrium evolution code. A good agreement is obtained between modeling and experiment. At the same time, the volt-second consumption for the entire duration is analyzed.

Disruption simulation for the EAST plasma

NIU Xing-ping1, WU Bin2

2007, 27(4): 286-291.

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The disruptions due to vertical displacement event for the EAST plasma are simulated in this article by using the TSC program. Meanwhile, the evolutions of the halo current and stress on vacuum vessel are calculated; the disruptions at different initial conditions are compared with each other, and killer pellet injection is simulated for the device fast shutting-down.

Calculation of steady-state time for plasma impurity

CHENG Fa-yin, LIN Rui

2007, 27(4): 292-295.

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Using the method of parameter transformation, the rate equations of impurities have been transformed to a vector equation with tri-diagonal symmetric coefficient matrix, and then solved numerically. Curves of characteristic parameter as function of electron temperature for a few typical light impurity in fusion plasma (such as helium, carbon, oxygen, neon and argon) have been obtained. Results show that values for the selected light impurities are within 10¹⁵～10¹⁹m^-3•s, and average steady-state times have not explicit correlation with nuclear charge Z. The last two peak values for the corresponding impurities are similar, and the time required to reach steady state for the dominant helium-like and neon-like ions is relatively short.

Power deposition of electron cyclotron waves in hot plasmas

PENG Xiao-wei, GONG Xue-yu, LIU Wen-yan, LIU Yan, YIN Chen-yan

2007, 27(4): 296-300.

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The power deposition of electron cyclotron waves in hot and dense plasmas is investigated by solving the relativistic dispersion relation with finite Larmor radius corrections, and the results are compared with those gained from weak relativistic Fokker-Planck equation. It is shown that the wave deposition profile in hot and dense plasmas is rather narrow, and the magnitude and profile of power deposition are affected by change of parallel refractive index, poloidal launching location and wave frequency. As the parallel refractive index turns to large, wave damping will decrease due to the FLR effect.

Application of FFT phase comparator technique to electron density measurement on the HL-2A tokamak

LI Yong-gao, ZHOU Yan, DENG Zhong-chao, YI Jiang

2007, 27(4): 301-305.

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A new phase comparator technique, called FFT, was introduced and applied successfully to the calculation of electron density ne for the interferometer data on the HL-2A tokamak. After calculating a great number of the experimental data and comparing the results with another two old methods: hardware and conventional software, the correctness and reliability of FFT have been affirmed. FFT can not only give the electron density curve in truth, but also overcome the jump and excursion of density curve at a certain extent. Whereas, without real-time calculation is its own defect.

Observation of edge fluctuation characteristics on the HL-2A tokamak

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

2007, 27(4): 306-310.

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The edge plasma fluctuation characteristics are studied by the reciprocating fast scanning 6-probes in the boundary region of the HL-2A tokamak. The probes can be applied to measure, simultaneously, the temporal and spatial profiles of the edge plasma parameters, the relationship of Reynolds stress with the poloidal flow and the zonal flows, the changes of radial particle flux and radial heat flow in one discharge. These parameters are used to analyze edge turbulence and coherency under the condition of multi-pellet injection (MPI) and supersonic molecular beam injection (SMBI). The results suggest that SMBI and MPI can influence the edge fluctuation characteristics, the radial gradient of Reynolds stress is able to drive zonal flows, as well as the turbulence and the transport may be suppressed.

Optimization design of first wall structure of Chinese TBM for ITER solid breeder blanket

YUAN Tao, FENG Kai-ming, WANG Xiao-yu, CHEN Zhi

2007, 27(4): 311-314.

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Based on structure design and thermo-hydraulic analysis of the ITER HCSB TBM, the first wall, which is the most important component of the TBM, is optimized. The code of programmable command stream of the finite element ANSYS is used to simulate the temperature and stress field of front panel in the first wall structure of the HCSB TBM. The optimized scheme of front panel of the first wall has been presented within the constraints of the temperature and stress of structure material.

Structure optimized design and seismic response analysis of S-bend box for ITER feeder

WANG Kai-song1, ZHAO Han1, SONG Yun-tao2

2007, 27(4): 315-319.

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Optimized design and check on wall thickness and distributing strengthening rib of the S-bend box were taken by static intensity analysis. Based on the mode analysis, seismic spectrum response analysis and dynamic time-history analysis were conducted. The results show that the parameters are reasonable.

Thermal hydraulic performance and structural thermal stress analysis for ITER shield blanket module

KANG Wei-shan, ZHANG Fu, WU Ji-hong, XU Zeng-yu

2007, 27(4): 320-323.

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Hydraulic and thermal analyses of the shield block have been done to examine whether the current design meets the ITER requirements or not. Firstly, the loss coefficient in the flow driver was calculated from individual analysis with CFD code. Then, the pressure drop, velocity and heat transfer coefficient were obtained in the cooling system through a optimised model. Finally, the thermal analysis was carried out based on the hydraulic results with FEM code to examine the distribution of temperature and thermal stress. The analysis results show that the current design is more efficient to reduce the energy loss and improve the cooling efficiency, and satisfy the ITER requirements. Of course, further optimisation or improvement is still needed to ensure safety operation.

Joule heating effect in liquid metal Hartmann flow

MAO Jie

2007, 27(4): 324-327.

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The temperature rise in liquid lithium Hartmann flow at electrically conducting walls due to Joule heat has been investigated numerically. It is shown that the temperature along the flow at the fluid wall interface may rise by over 100?C owing to the Joule heat generated by inductive current within the thin conducting walls.

Calibrate technology of the EAST lower hybrid wave antenna background phases

XU Hui, SHAN Jia-fang

2007, 27(4): 328-333.

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A calibrate technology of background phases in two main parts is introduced in the EAST lower hybrid wave antenna phases collection and control system. One part is referred to static calibration of the background phases caused by tangency of phased multi-junction grill antenna and plasma. The other part is referred to dynamic calibration of the alterable background phase caused by soft wave-guide flex when the antenna is being moved. The calibrate technology of lower hybrid wave antenna background phases provides an exact phase base point of phase feedback control system. It could be a foundation for the consistency of the pre-establish phases and actual phases.

Distributed acquisition and control system based on QNX

WANG Dong-xia, WANG Mao, SHAN Jia-fang

2007, 27(4): 334-338.

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Distributed acquisition and control system based on QNX are described. The master computer is used to acquire and control the power of microwave according to the parameters given by slave computer. The slave computer sends the controlling parameters to the master and display the waveform. The slave computer also can start and stop the master program remotely. After some tests of LHCD system on EAST, the real time property and reliability of the system are satisfactory very well.

A new way of soft X-ray spectrum measurement in the HL-2A tokamak

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

2007, 27(4): 339-342.

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A soft X-ray spectrum measurement system is newly developed for the real-time acquisition, data processing and display of electron temperature. In this system, a personal computer with high-speed A/D acquisition card is used to obtain the original analog data and processing software is specially developed to calculate the electron temperature. Compared with PHA (Pulse Height Analyzer), the new system provides a way to set channel number and time solution by software. This method has been applied in the HL-2A tokamak experiment, and the result shows a good agreement with the electron temperature tested by other measurements.

Theoretical calculation for thermodynamics function of thermal plasmas

QIN Pan, LI Xiang, TAO Xu-mei, RAN Yi, YU Hui, DAI Xiao-yan, YIN Yong-xiang

2007, 27(4): 343-347.

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Based on statistical thermodynamics and chemical equilibrium theory, citing the spectral data of the atom and molecule, the thermodynamics function(H、C_{p, m}) of diatomic molecule system at thermo-equilibrium is derived in the temperature range from 300K to 20000K. As an example, the dependence of molecular dissociation, atomic ionization and the molar heat capacity for nitrogen plasma system are given. It is shown that the results are in good agreement with those from empirical formula at lower temperature (T<3800K). The results in the higher temperature range are analyzed and discussed, and an analytic expression is given by the least-squares method for the molar heat capacity of nitrogen system.

Power spectra estimation of ICF capsule surface topography

GE Shuang-quan1, MA Xiao-jun2, GAO Dang-zhong

2007, 27(4): 348-351.

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The ICF capsule surface data on three orthogonal directions have been measured with a surface profile-meter. Surface debris and eccentricity were found to be the main error source of measurement; the methods to eliminate the tow errors and steps to pre-process these data were put forward, furthermore, the least square method was adopted to evaluate the capsule’s roundness. Finally, an average one-dimensional spectra calculation method was given, and the relation between mode-spectra curve and capsule surface topography were presented.

Determination of rotational temperature in DBD assisted by spark discharge

QI Bing, REN Chun-sheng, ZHANG Yu-tao, WANG De-zhen, MA Teng-cai

2007, 27(4): 352-356.

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Uniform glow-like discharge is generated in a spark pre-ionization assisted dielectric barrier discharge device at atmospheric air. The emission spectrum of the 1st negative band of N₂⁺ ( B²∑→X²Σ) (0, 0) has been analyzed by means of spectrum simulation and Boltzmann plot method, and the rotational temperatures have been diagnosed. The results show that the rotational temperatures vary with the applied frequencies and discharge modes, and about 70K higher than those in filament mode.

Electrical characteristic simulation of double-faced glow discharge plasma reactor system

AN Zhi-yong, LI Ying-hong, SONG Hui-min

2007, 27(4): 357-362.

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Simulation of the electrical characteristics of atmosphere uniform glow discharge plasma (OAUGDP) reactor system has been conducted with the Matlab software. Plasma discharge is modeled as a voltage-controlled current source: the discharge current outputs and follows a power law of the applied voltage when the voltage across the gap exceeds the plasma initiation voltage. Simulation results agree well with experimental data. It is also found that the voltage power laws to describe OAUGDP are dissimilar for different operating regimes, and therefore the discharge current waveforms are different.

Nuclear Fusion and Plasma Physics Vol.27 ( 2007 )

2007, 27(4): 363-368.

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