Nuclear Fusion and Plasma Physics

A numerical model for the equation of state for condensed matter

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

2011, 31(2): 97-104.

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A numerical model for the equation of state for condensed matter is developed in the form of three-term type: the electronic thermal pressure and thermal energy are computed by using Faussurier’s average atom model; the ionic thermal pressure and thermal energy are calculated using Cowan’s ion model; the cold pressure and cold internal energy come from a semi-empirical fitting formula based on experimental data. The average ionizations computed by the average atom model are compared with experimental data. The equation of state combined with Hugoniot relation is used to calculate the Hugoniot curves of beryllium and aluminum, in which the electron shell-structure effect is embodied obviously.

On mutual exclusiveness between time-varying and static shear flow in turbulence suppression

XIE Tao1, ZHANG Yang-zhong2, WANG Ai-ke1

2011, 31(2): 105-111.

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The analytical theory of turbulence suppression by shear flow is applied to analyze the effects from time-varying as well as static component. It is found that each component may yield the same suppression level when appearing alone. However, when both the components co-exist, one tends to diminish the suppression caused by the other in fairly wide parameter ranges, which agrees with the Maeyama’s simulation results published recently, in particular, the mutual exclusiveness is maximized as the strengths of the two components have the nearly same size. The adopted averaging method of asymptotic theory reveals that it is the coupling between the time-varying shear flow and the induced time-varying relative orbit motion that causes the asymmetry of the two components in turbulence suppression.

Bohm criterion of the sheath in the multicomponent electronegative collisional plasma

ZHAO Xiao-yun1, DUAN Ping2, QU Kui1

2011, 31(2): 112-116.

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The Bohm criterion of the sheath in the multicomponent electronegative collisional plasma is developed with a two-fluid model. It is discussed that different charge particles affect the Bohm criterion for the sheath of a one-dimensional stationary plasma. Numerical calculation results are obtained through quasi-Newton method. It is shown that the upper and lower limits for the sheath criterion exist. And the ion Mach number increases with the increase of secondary electron emission coefficient, it decreases with the increase of negative ions. In addition, the upper and lower limits for the sheath criterion depend on the temperature of ions, the ion-neutral collision and the charge of the ions.

Spectral line shift of He-like chromium in hot and dense plasmas

HU Feng1, 2, YANG Jia-min1, WANG Chuan-ke1, ZHANG Ji-yan1, JIANG Gang2

2011, 31(2): 117-121.

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By assuming the ion sphere model, the self-consistent filed model for the Poisson-Boltzmann equation and the Dirac equation is used to calculate the energy levels of He-like chromium in hot and dense plasmas. Consequently, the spectral shifts the intercombination line and the resonance line and the shifts of the exchange energy of He-like chromium in hot and dense plasmas are studied. The results show that the two electric dipole transitions red shift nearly linearly with the increase of plasma electron density. The formula of the linear relationship is found. The results may be useful in developing the new model of dense plasma diagnosis.

Analysis of X-ray spectrum from aluminum plasmas generated by 120TW/30fs laser pulse

YU Xin-ming, YI You-gen, HU Feng, ZHAO Yang, PU Yu-dong, YANG Jia-min, ZHANG Ji-yan, ZHENG Zhi-jian

2011, 31(2): 122-126.

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The hot dense aluminum plasmas have been generated by the interaction with 120TW/30fs laser pulse on the SILEX device. In order to diagnose electron temperature, two different ways have been introduced, which achieved the same result. Using the intensity ratio of H-like resonant to He-like resonant, the temperature between 480eV and 670eV has been derived, the temperature between 430eV and 610eV achived by the Li-like satellite (jkl) to He-like resonant. The electron density is derived from the intensity ratio of He-like intercombination to He-like resonant, the diagnosed electron density is from 2.6×10²⁰cm^-3 to 5.3×10²⁰cm^-3. The evolution of the intensity of H-like resonant, He-like resonant, Li-like satellite (abcd, qr, jkl) to laser power intensity have been depicted in two laser intensity contrast ratio.

Structural analysis of HL-2M vacuum vessel under major plasma disruption

CAI Li-jun, LIU De-quan, RAN hong, LI Yong, CAO Zeng

2011, 31(2): 127-132.

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The eddy currents and electromagnetic forces on the HL-2M vacuum vessel during major plasma disruption were calculated by using ANSYS finite element software, and a subsequent static stress analysis was carried out based on the electromagnetic forces. The results showed that the toroidal eddy currents and radial electromagnetic forces were discovered on the vacuum vessel and mainly concentrated on the straight section of the vessel shells and the vacuum vessel is strong enough to bear the electromagnetic loads.

Study on the filament temperature distribution of neutral beam ion source on HL-2A tokamak

WEI Hui-ling, CAO Jian-yong, JIANG Shao-feng, LEI Guang-jiu, Lu Da-lun, DUAN Xu-ru

2011, 31(2): 133-138.

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The filament resistance characters of multipolar cusped field bucket ion source on HL-2A tokamak NBI system was firstly introduced, and the filament steady temperature distribution was calculated with a 1 dimensional numerical model. When arc discharge is off, the filament temperature distribution at different filament current and the corresponding filament resistances are calculated. When the arc discharge is on, with the current exported by the filament electrical source being 120A and the approximation of the plasma sheath layer on the filament surface, the filament temperature distribution and the filament resistance at different arc current are calculated. The limited arc discharge current corresponding thaw of tungsten filament is presented. At last, the brief analysis and discussion of the warp between the calculated results and the experiment measured values were given.

Simulation of neutral beam injection on EAST by NUBEAM

WANG Jin-fang, WU Bin, HU Chun-dong

2011, 31(2): 139-145.

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The role of the injection angle (the angle between the axis of the neutral beam injection system and the center of the injection window) on the neutral beam current drive, heating efficiency and beam shine-through power are studied with NUBEAM code to explore the optimum injection angle for the EAST NBI system. From the simulation results, under the limitation of the actual project, it is indicated that an injection angle of 19.5° is the optimum for EAST with its typical experimental parameters. With this injection angle, the increase of the plasma density can improve the current drive and heating efficiency and reduce the beam shine-through power.

Electromagnetic analysis of the Faraday shield of the EAST ICRF antenna

YANG Qing-xi, SONG Yun-tao, WU Song-tao, ZHAO Yan-ping

2011, 31(2): 146-150.

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Faraday shield is one of the important components of ICRF antenna for EAST. In view of the structural safety of the Faraday shield, the electromagnetic and structural analyses for the Faraday shield have been carried out by applying the finite element method and the formulas under the cases of plasma disruption and vertical displacement event (VDE). Results of the electromagnetic forces, the stresses distribution as well as the deformation in the Faraday shield have been obtained under the two cases. They meet the design requirements and provide the theoretical basis for the structural safety evaluation of the Faraday shield.

Research of the signal attenuation of the 70m twisted pair on the EAST tokamak

DAI Xiao-jing, SHEN Biao, JIANG Li, LIU Guang-jun

2011, 31(2): 151-155.

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In order to analyze the impact brought by the 70m twisted pair in the electromagnetic measurement system of the EAST tokamak, the equivalent circuit model of the electromagnetic coil and twisted pair was established, and circuit models with twisted pair and without twisted pair are designed, the these two circuit models are simulated with the simpolor6.0 software. By analyzing the transfer function of the two models and the voltage peak to peak of the simulation output, it is proved that the effect of the using the 70m twisted pair in the electromagnetic measurement system can be neglected.

Thermodynamics performance study of cryostat feed of ITER correction coil system

WANG Kai-song1, DONG Biao1, WANG Zhong-wei2, CHENG Yong2

2011, 31(2): 156-160.

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According to ITER device requirements for cryostat feed through(CFT) technical characteristic and special low temperature and high vacuum environment under feeder systems working condition, taking heat conduction and radiation heat transfer into account, adopting finite elements analysis, feeder systems were engaged in steady state thermal analysis, transient thermal analysis, coupled analysis between structure and heat conduction. The temperature distribution, heat leakage, temperature-time curve and deformation time cure can be obtained, which offer the basis for the design and the improvement of CFT.

Thermal-hydraulic and thermo-mechanical analyses of current ITER shield blanket design

KANG Wei-shan, ZHANG Xiu-jie, YUAN Tao, CHEN Ji-ming

2011, 31(2): 161-166.

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The current design of ITER shield blanket is introduced, and much attention is paid to the comparison between 2004 DDD design and the current design in the structure of first wall and shield block. Besides, the thermal-hydraulic analyses and thermo-mechanical analyses of shield block of No.8 blanket module was performed. The results of analyses indicate that the maximum temperature of No.8 blanket module is below 200ºC and its maximum Von-Mise stress is less than 200MPa, thus the current design of the shield block satisfies with the ITER related requirements, except that the pressure drop is a little bit large, coming up to 0.44MPa. Moreover, the uncovered shield block frontal surface exposed to plasmas heat flux was studied, and its ability of the loaded heat flux was evaluated and optimized based on the result of thermo-mechanical analysis to get a reasonable design pattern.

Electromagnetic analysis of diagnostic port plug and its influence to structure of ITER

CAO Wen-gang, WU Hai-long, XU Tie-jun, HU Qing-sheng, JIN Chuan-shan, ZHU Xiao-wen

2011, 31(2): 167-171.

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In order to study the influence on the diagnostic plug caused by plasma disruption of ITER, ANSYS was used to build the model and simulate its physical environment for electromagnetic field analysis and obtain the trend of eddy current and electromagnetic load. The electromagnetic loads were coupled with the structure model to obtain its influence on the structure. The strain and stress distribution of the structure were obtained, which offer the basis for evaluating the diagnosis plug structure reliability.

Activation method for measuring pulse neutron yield of DT fusion reaction

SONG Chao-hui, GUAN Xin-yin, ZHANG Zi-chuan

2011, 31(2): 172-175.

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In order to measure the neutron yield of DT pulse neutron source, a silver-activated detector was designed. The detector consists of neutron moderator (slowing-down materials), natural silver foils, plastic scintillators and a photomultiplier tube (PMT). The output current of the detector was recorded by a micro-current-meter. By comparing and analyzing the differences between the output current curves of the detector which were measured under the constant radiation source and that of the pulse neutron source, characterized parameters were deduced. So the yield of DT pulse neutron source could be calculated. It is proved that this new method reduces the dependence of the cross section data, and it is very simple and convenient for on-line measurement.

A new shunt DC active power filter scheme of power supply in steady high magnetic field facility

WANG Lei, LIU Xiao-ning

2011, 31(2): 176-180.

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In view of the series DC active power filter in other SHMF and shunt PWM DC active power filter, the shunt linear adjustment active power filter scheme was proposed. The structure and principle of shunt linear adjustment active power filter was introduced. The realizing scheme of the DC active power filter was also analyzed. Simulation model of the shunt linear adjustment active power filter is established, and the simulation results verify the parameter design is reasonable. An experimental prototype is developed, the experimental results show that the filter has good filter effect.

A pulsed electromagnetic valve for gas puffing in a plasma dynamic accelerator

FENG Chun-hua, FANG Tong-zhen, WANG Long, YANG Xuan-zong, HUANG Jian-guo, CHEN Chao-feng, HAN Jian-wei, SUN Yuan-cheng

2011, 31(2): 181-185.

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A pulsed electromagnetic valve for gas puffing in a plasma dynamic accelerator was designed and manufactured. The rise time of the gas pulses is less than 0.1 ms and the pulse width is in the range of 0.2~2 ms. The puffed gas amount is 10²¹~10²²molecules. The motion of the valve head is simulated with a set of partial differential equations. The computational results give a reasonable explanation for the abrupt jump appearing in the dependence of some gas puffing parameters on the charge voltage.

A two-temperature chemical non-equilibrium modeling of DC arc plasma

QIAN Hai-yang, WU Bin

2011, 31(2): 186-192.

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To a better understanding of non-equilibrium characteristics of DC arc plasma, a two-dimensional axisymmetric two-temperature chemical non-equilibrium (2T-NCE) model is applied for direct current arc argon plasma generator with water-cooled constrictor at atmospheric pressure. The results show that the electron temperature and heavy particle temperature has a relationship under different working parameters, indicating that DC arc plasma has a strong non-equilibrium characteristic, and the variation is obvious.

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