Nuclear Fusion and Plasma Physics

Nonlinear dynamic response for cantilever conductive thin plate due to magnetoelastic interaction

ZHANG Jian-ping, DAI Yong-xia

2009, 29(4): 289-294.

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For the limiter blade in fusion reactor under the complicated magnetic field, a cantilever conductive thin plate was employed as its simplify structure，and a theoretical model was established to describe the dynamic response behavior of geometric nonlinearity under the condition of mechanics-electricity-magnetism interactions based on electromagnetic and mechanical basic laws and equations of conductive media. The solving processes for numerical calculation were given, and the influences of in-plane magnetic volume forces and geometric nonlinearity on the deformation of thin plate were quantitatively simulated. The simulation results indicate that it is not necessary to take in-plane magnetic volume forces and the deformation into account under the condition of fairly small transverse magnetic field while their effects are more obvious with the increase of transverse magnetic field, and that the deflection peak with geometric nonlinearity is smaller than that from linearity. Therefore, the effects of geometric nonlinearity and in-plane magnetic volume forces are synchronously considered in the conductive structure design.

Profiles of zonal flows and turbulence mode numbers and probe system in the HL-2A tokamak

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

2009, 29(4): 295-300.

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The toroidal and poloidal symmetries(m~0, n~0) of the measured low frequency zonal flows (f=0~5kHz) and geodesic acoustic mode zonal flow(f=16kHz) electric potential and radial promulgate features were unambiguously identified with displaced Langmuir probe arrays in the edge plasma of the HL-2A tokamak for the first time. The finite radial wave vector (K_r-LF=0.6cm^-1, K_r-GAM=2cm^-1)of the flows was simultaneously estimated. The formation mechanism of the flows is identified to be nonlinear three wave coupling between high frequency turbulent fluctuations and the flows. Changes of zonal flow amplitude bring by ECRH power and the boundary safety factors were simply studied. Moreover, change of zonal flow amplitude in radial direction was too observed.

Study on vertical displacement instability on EAST tokamak

LIU Cheng-yue, CHEN Mei-xia, WU Bin

2009, 29(4): 301-304.

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The whole vertical displacement instability process for EAST tokamak and the evolution of plasma magnetic axis vertical displacement with time have been described. The vertical displacement instability growth rates have been obtained. The modeling results are well in agreement with the experiment ones.

Simulation of lower hybrid wave coupling power spectrum with poloidal effects

QIN Yong-liang, DING Bo-jiang, JIA Hua, ZHANG Li-zhi, MENG Ling-guang, KUANG Guang-li

2009, 29(4): 305-308.

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The coupler of LHCD on HT-7 tokamak is constituted with standard wavegudes, whose length and width are constant. Considering of the possible poloidal phase difference between the up and down guides and electromagnetic interference, we get the power spectrum lower hybrid wave in both poloidal and toroidal direction by the way of simulation. Due to the poloidal wave vector, the incident direction of lower hybrid wave launching into plasma will be changed. In the last, the incident angle of lower hybrid wave launching into plasma is simply estimated and discussed under the different poloidal phases.

Simulation of lower hybrid wave coupling power spectrum with poloidal effects

WEI Wei, DING Bo-jiang, ZHANG Ting, LUO Le

2009, 29(4): 309-314.

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The coupler of LHCD on HT-7 tokamak is constituted with standard wavegudes, whose length and width are constant. Considering of the possible poloidal phase difference between the up and down guides and electromagnetic interference, we get the power spectrum lower hybrid wave in both poloidal and toroidal direction by the way of simulation. Due to the poloidal wave vector, the incident direction of lower hybrid wave launching into plasma will be changed. In the last, the incident angle of lower hybrid wave launching into plasma is simply estimated and discussed under the different poloidal phases.

Simulation of the MHD stabilities of the experiment on HL-2A tokamak by GATO code

PAN Wei, CHEN Liao-yuan, DONG Jia-qi, SHEN Yong, ZHANG Jin-hua

2009, 29(4): 315-319.

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The ideal two-dimensional MHD stabilities code, GATO, has been successfully immigrated to the high-performance computing system of HL-2A and used to the simulation study of the ideal MHD stabilities of the plasmas produced by one of the pellets injection experiments on HL-2A tokamak. The EFIT code was used to reconstruct the equilibrium configures firstly and the GATO was used to compute their MHD stabilities secondly whose source data were obtained by the No.4050 discharge of the experiments on HL-2A, and finally by analyzing these results the preliminary conclusion was devied that the confinement performance of the plasma was improved because of the stabilization effect of the anti-sheared configures created by the pellets injection.

Study of plasma boundary identification in the SUNIST spherical tokamak

LIU Jian, FENG Chun-hua, YANG Xuan-zong, WANG Long

2009, 29(4): 320-323.

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Simulation of plasma boundary reconstruction in the SUNIST spherical tokamak using current filament (CF) model has been demonstrated. The calculation results show that plasma free-boundary can be identified by filament current method quickly. The average boundary error in radius is less than 6mm between CF model and EFIT code.

Development of 2MW ECRH system on the HL-2A tokamak

RAO Jun, LI Bo, ZHOU Jun, YAO Lie-ying, KANG Zi-hua, WANG Ming-wei, LI Li, FENG Kun, HUANG Mei, LU Zhi-hong, ZHANG Jin-song, LI Qing, LIU Yong

2009, 29(4): 324-330.

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The main parameters of ECRH system in HL-2A tokamak are output power 2MW, pulse duration 1s and frequency 68GHz. The system consists of four units, which are comprised of a gyrotron, a transmission line and control, protection, measurement and cooling subsystem each. After commissioning, the 500kW/1s output power has been obtained for every gyrotron and the total output power was up to 1.63MW for four gyrotrons parallel operation. The efficiency of the ECRH system is over 80%.

Design of divertor cooling structure for EAST superconducting tokamak

XIE Han, SONG Yun-tao, YAO Da-mao

2009, 29(4): 331-334.

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The structure and relative analysis of divertor are introduced for EAST superconducting tokamak. The thermal conductivity of material of first wall and heat exchange performance of divertor structure are tested to approve their reliability.

Analysis of residual strain for Nb₃Sn superconducting strand in low temperature

LIU Fang, WU Yu, YU Min, LIU Bo, NI Zhi-peng

2009, 29(4): 335-340.

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Assuming that the materials in the strand are elastic, equations are shown for calculating the residual stress for the component of Nb₃Sn strand. An elasto-plastic one dimensional finite element model, including temperature dependent stress-strain curves, annealing and manufacturing process stresses, is used to derive the internal stresses of Nb₃Sn strands. The influence of steel jacket has been calculated for Nb₃Sn strand by the model.

Conceptual design of HL-2M tokamak control system

XIA Fan, CHEN Liao-yuan, SONG Xian-ming, ZHANG Jin-hua, LUO Cui-wen, PAN Yu-dong

2009, 29(4): 341-347.

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The static architecture, dynamic behavior, control theory and simulation of HL-2M tokamak control system are described. The real-time network will be build for the communication of real-time control among its subsystems and universal timing system will be build to guarantee the synchronization among the subsystems. The duty to achieve preprogrammed parameters is carried out by plasma discharge control. In order to reduce the damage made by discharge exception, the error-handling mechanism of supervision system is considered. The controllers of magnetic control system are designed to control the current, shape and position of plasma and simulation system is designed for testing the controllers.

Transient thermal analysis for the first-wall of CH HCSB TBM

ZHAO Zhou, FENG Kai-ming, ZHANG Guo-shu, YUAN Tao

2009, 29(4): 348-352.

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The steady thermal analysis for the first-wall of CH HCSB TBM module is carried out firstly using the general FE code ANSYS. The results show that the maximum temperature of beryllium armor and RAFM steel of first-wall meet the thermal design requirements. Based on the change of the first-wall surface time-dependent heat flux, the transient thermal analysis also is performed, and the dependence results are given. And the two typical accidents of first-wall are analyzed preliminarily, the analytic result and accident effect are discussed.

Analysis of magnetic shielding performance for ITER gas valve boxes by finite element method

XIA Zhi-wei, LI Wei, LU Jie, LI Bo

2009, 29(4): 353-356.

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The analysis of magnetic shielding performance for ITER gas valve boxes is done by Ansoft Maxwell 3D software. A new enclosed cylinder model is applied and the magnetic shielding performance is obtained under various boundaries, shield thicknesses, hole sizes and slot sizes. Based on these results, a possible design with proper parameters is given.

Design on alignment system of ITER remote handling transfer cask

ZHOU Zi-bo, YAO Da-mao, LI Ge, CAO Lei, Qin Shi-jun

2009, 29(4): 357-360.

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Alignment system of ITER transfer cask consists of pallet and alignment pins. Pallet is equipped with all the components to allow the docking of the cask in front of VV port, drive envelope in different direction and produce the necessary pushing and reaction force. Alignment pins act as leading and reference. Alignment system can assure enclosure correctly accurately alignment with port. The detailed structure designs of function components of alignment system are shown in the paper. The necessary adjustment ranges and accuracies are also provided.

Doppler shift spectroscopy for the measurement of ion species of HL-2A neutral beam injector

YANG Li-mei, YU Li-ming, YU De-liang, HAN Xiao-yu, LEI Guang-jiu, DUAN Xu-ru

2009, 29(4): 361-364.

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On the NBI test-bed, the ion species of the extracted ion current of ion source and their variance with the arc current have been obtained by taking advantage of optical diagnostic on the basis of Doppler shift. A method based on GA and L-M has been proposed to analyze the experimental spectrum. The results show that the ratio of H⁺, H₂⁺and H₃⁺is about 0.57:0.36:0.07 as the beam energy of 30keV and arc current of 340A. When the arc current varies from 90A to 350A, the percentage of H⁺ increases from 45% to 57%, whereas the H₃⁺decreases from 17% to 7%.

Analysis of photonic band gap in inhomogeneous plasma photonic crystals

LIU Song, LIU Shao-bin

2009, 29(4): 365-369.

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A finite-difference time-domain (FDTD) algorithm is applied to study the propagation of electromagnetic waves in plasma photonic crystals (PPCs). A perfectly matched layer absorbing technology is used in these simulations. The reflection and transmission coefficients of electromagnetic wave through PPCs are computed numerically. The results of photonic band gap characteristics are discussed in terms of plasma density, plasma temperature, dielectric constant ratios and layer defect.

Time-space resolved diagnosis for the parameters of aluminium plasma produced by YAG laser

XUE Quan-xi, YE Xi-sheng, ZHAO Xue-qing, ZHANG Yong-sheng

2009, 29(4): 370-374.

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The time-space resolved optical spectra of aluminium plasma produced by 532nm YAG laser have been obtained by OMA and other equipments. The curves of time-space resolved electron temperature and density were deduced by LTE model and Stark broadening. The results were consistent with those in references [9～11].

Suppression of the noise of surface wave plasma antennas by a new radio frequency source

XIANG Qian, WANG Shi-qing, XU Ling-fei, YAN Ze-lin, LI Jian

2009, 29(4): 375-378.

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A new technology combining digital frequency synthesis with power gain automation is put forward to stabilize the output frequency and the power of the plasma excitation source, thus, to reduce the noises and improve the plasma antenna properties. The experimental results prove the feasibility of this method.

Nuclear Fusion and Plasma Physics Vol.29(2009)

2009, 29(4): 379-384.

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