Nuclear Fusion and Plasma Physics

Magnetic coordinates with straight field lines

SHI Bing-ren

2014, 34(4): 289-294.

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A method for constructing the magnetic coordinates in which the magnetic field lines are straight is described. This coordinate system is widely used in the magnetohydrodynamic stability and kinetic physics analysis and calculations for tokamak plasmas, however, there is less detailed description about its construction in literatures. Here we describe the basic features of this coordinates for several kinds of tokamak and spherical torus configurations.

Surface temperature measurement and energy flux estimation of the mobile limiter on HT-7 tokamak

SHI Bo , WANG Wei-hua , GONG Xian-zu , YANG Jin-hong

2014, 34(4): 295-298.

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The temperature measurement of the mobile limiter by infrared camera was performed on HT-7 tokamak. The high temperature zone of the ion side and electronic side, and the movement of the high temperature zone reflecting the relationship of first wall temperature and horizontal displacement, were observed. According to the relationship of first wall temperature and the limiter position, it is speculated that the plasma boundary is between 268mm and 266mm. The results also show the relationship of first wall temperature and wave heating status. The energy flux on the surface of the mobile limiter was obtained by ANSYS analysis. The results and method can provide reference for the temperature measurement and energy flux estimation on the first wall of EAST and other tokamaks.

Determination of radial profile of ICF hot spot’s state by multi-objective parameters optimization

DONG Jian-jun, DENG Bo, CAO Zhu-rong, DING Yong-kun, JINAG Shao-en

2014, 34(4): 299-306.

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A method using multi-objective parameters optimization is presented to determine the radial profile of hot spot temperature and density. And a parameter space which contain five variables: the temperatures at center and the interface of fuel and remain ablator, the maximum model density of remain ablator, the mass ratio of remain ablator to initial ablator and the position of interface between fuel and the remain ablator, is used to described the hot spot radial temperature and density. Two objective functions are set as the variances of normalized intensity profile from experiment X-ray images and the theory calculation. Another objective function is set as the variance of experiment average temperature of hot spot and the average temperature calculated by theoretical model. The optimized parameters are obtained by multi-objective genetic algorithm searching for the five dimention parameter space, thereby the optimized radial temperature and density protiles can be determined. The radial temperature and density profils of hot spotby experiment data measured by KB microscope cooperating with X-ray film are presented. It is observedthat the temperature profile is strongly correlated to the objective functions.

Energy distribution of the fast electron from Cu and CH targets irradiated with fs-laser pulses

CAI Da-feng,GU Yu-qiu,ZHENG Zhi-jian, ZHOU Wei-min, JIAO Chun-ye

2014, 34(4): 307-313.

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In order to investigate the effect of target’s material on fast electron energy distribution, the energy distribution of fast electrons from the front and the rear of Cu and CH targets have been measured during the interaction of femtosecond laser-foil targets. The results show that the fast electron spectrums from the front of Cu and CH targets are similar, which show energy distribution of fast electrons depends very little on material of targets. The fast electron spectrums from the rear of Cu and CH targets are obviously dissimilar, which indicate a mighty effect of target material on fast electron transport. The fast electron spectrums from the Cu target is “soften”, which is due to electron recirculation and self-magnetic field produced by electrons transported in the target. The fast electron spectrums from the CH target is a Maxwellian distribution, which is due to collision effect when electrons transport in the target.

Updated design and development on key technology for CH HCCB TBM

HU Gang, FENG Kai-ming, ZHAO Zhou, ZHANG Guo-shu, WANG Qi-jie, CAO Qi-xiang, WANG Ze-ming, YU De-huai, TAO Shi-quan, WANG Shi-zhong, TAO Hai-yan

2014, 34(4): 314-319.

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Based on port C of ITER machine, design of Chinese helium-cooled ceramics breeder test blanket module (CH HCCB TBM) is updated and its main properties and design parameters are given by comprehensive analyses including neutronics optimization, structure mechanics analyses, thermo-hydraulics and thermo-mechanics analyses, flowing analyses, electromagneticanalyses and fabrication consideration. Chinese updated TBM is designed with 484mm in toroid, 1660mm in longitude and 675mm in poloidal. According to this design, fabrication processes such as vacuum diffusion welding and vacuum electron-beam welding on new material CLF-1 being developed are studied. Fabrication procedures for key components such as first wall etc. are explored. Mockups for first wall and submodules’ cooling plates have been trial-produced.

Preliminary thermal-hydraulic design and simulation for hybrid breeder blanket

WANG Xiao-yong, LI Zai-xin, ZHAO Feng-chao, ZHAO Zhou, WU Xing-hua, WANG Qi-jie

2014, 34(4): 320-325.

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Thermal-hydraulic design and analysis for the new conceptual design of fusion-fission breeding reactor using casing pipes for fuel assembly was done. Based on typical thermal-hydraulic design parameters, preliminary thermal-hydraulic design for the blanket was proposed. The corresponding temperature distribution and pressure distribution were obtained using thermal-hydraulic codes, CFX. The simulation results showed that maximum temperature of the materials were all below their corresponding temperature limits, coolant temperature at the outlet was higher than 773 , and pressure drop of the coolant could satisfy engineering requirement. T ℃ he reasonability of this thermal-hydraulic design was preliminarily verified.

Electromagnetism optimization and analyses of 8T high temperature superconducting solenoid magnet

SUN Lin-yu, LI Peng-yuan

2014, 34(4): 326-329.

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An optimization method of electromagnetic performance of high temperature superconducting solenoid magnet in high magnetic field is introduced. A Matlab code is written for optimizing the performance of the magnet with the central magnetic field of 8T and the inner diameter of 20 cm. Besides, the magnetic field distribution of the optimized magnet is analyzed by FEM software, and the value of the maximum magnetic induction in the axial direction is almost the same as the result calculated by the Matlab code.

Design and analysis of exchange device on fast dynamic probe system of the EAST tokamak

YAN Zhao-hui, ZHANG An-ning, LI Bo, ZHU Feng, ZHANG Wei

2014, 34(4): 330-334.

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The theoretical thickness of the material in the EAST fast dynamic probe exchange device was calculated, and 4mm with stiffener barrel-type and box-type entity model was established through the CATIA drawing software. The above two models were imported into ANSYS software and finite element analysis was adopted to analysis on the overall strength of the model for obtaining the maximum stress and strain data. By designing to increase the thickness of the wall, 5mm without stiffener cylindrical and box structure were set up and finite element analysis was made. By optimizing and contrasting the results of the analysis, maximum stress and strain of 5mm without stiffener cylindrical structure was the smallest. It concludes that 5mm barrel without reinforcement scheme is the most optimal. Finally, by making a pre-research model and doing vacuum leak detection, the test results meet the design requirements.

Fusion spectrum neutron source computation in 6 LiD convertor for HFETR

SUN Shou-hua, YE Bing, HU Yi-fei

2014, 34(4): 335-339.

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A computation model of 14MeV neutron from the ⁶LiD convertor has been established, the 14MeV neutron sources and flux in the irradiation samples from the 6 LiD convertor and the core have been computed separately, the neutron spectrum in the irradiation samples have been computed, too. The results show that the neutron sources that over 13MeV account for 1MeV above in the 6 LiD convertor is 25.7%、24.6% respectively, 14MeV neutron sources get 4.31×10 13 n_T⋅s ⁻¹、3.34×10 13 n_T⋅s ⁻¹, 14MeV neutron flux get 2.66×10 ¹⁰ n_T⋅cm ⁻²⋅s ⁻¹、3.53×10¹⁰n_T⋅cm⁻² ⋅s⁻¹ , as He and H₂O charged in the irradiation capsule.

Current status of design and manufacture on W/Cu interface of the fist wall material

LUO Lai-ma, TAN Xiao-yue, LUO Guang-nan, ZAN Xiang,ZHU Xiao-yong, WU Yu-cheng

2014, 34(4): 340-347.

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This paper reviews the current method of solving the W/Cu interface connection and relieving the thermal stress by added adaptation layer. After analyzing the different adaptation layer, the best W/Cu adaptation layer is selected, and then the W/Cu layer structure optimization analysis is conducted. The results show that using W/Cu functionally graded materials as the combination of the adaptation layer has enough strength, and good thermal conductivity are more effective to alleviate thermal stress. In addition, this paper expounds the current method which utilizes the successfully prepared W/Cu functionally gradient materials as W/Cu adaptation layer used in the first wall materials. Finally, this paper has made the summary and prospect about that the functionally gradient materials of W/Cu used as the adaptation layer tosolve the first wall material W/Cu interface connection.

Preparation technology of plasma facing ODS-W composites

ZHANG Jun,ZHU Xiao-yong , LUO Lai-ma,LUO Guang-nan , CHENG Ji-gui, WU Yu-cheng

2014, 34(4): 348-354.

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Addition of rare earth oxide to the tungsten can significantly refine the grain and improve high temperature stability of the tungsten alloys, which also have the dispersion strengthening effect and significant effect in the suppression of grain growth, controllingthe re-crystallization grain shape and improving the mechanical properties of the materials. This paper expounds current situation of several techniques of preparing ODS-W from the perspective of preparation method of ODS-W particles and forecasts its development trend.

Transient analysis of the output short-circuit fault of high power and high voltage DC power supply

YANG Zhi-gang, ZHANG Jian, HUANG Yi-yun,HAO Xu, SUN Hao-zhang, GUO Fei

2014, 34(4): 355-360.

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The transient conditions of output short-circuit fault of high voltage DC power supply was introduced, and the energy of power supply injecting intoklystron during the protection process of three-electrode gas switch were analyzed and calculated in detail when klystron load happening electrodearc faults. The results of calculation and simulation are consistent with the results of the experiment. When the output short-circuit fault of high voltage power supply occurs, switch can be shut off in the microsecond,and the short circuit current can be controlled in 200A. It has verified the rapidity and reliability of the three-electrode gas switch protection, and it has engineering application value.

Performance analysis on SNR of scientific grade optical CCD

WANG Ling-li, LI Shou-bei,ZHANG Hui-ge,WANG Zhe-bin,LIU Hao,ZHANG Chen,ZHANG Wen-hai,YI You-gen

2014, 34(4): 361-366.

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Based on the noise source, considering that the fluctuations of incident photons, dark current and biased signal satisfy the Poisson distribution, the corrected signal-to-noise-ratio (SNR) relation is obtained. On condition that the gain, readout rate and cooling temperature of CCD are set experimentally to be 3, 100kHz and −25°C respectively, the photon transfer curve is obtained. Meanwhile, by setting different experimental conditions，the effect of the dark current, readout rate and the system gain on the SNR of the scientific grade optical CCD is discussed respectively. The experimental results are in good agreement with the theory, which provides the good experimental basis for design of the scientific grade optical streak camera and building of the automated laboratory platform used for weak light calibration.

Strength analysis and optimal design of KTX vacuum vessel support system

WANG Zhen,SONG Yun-tao,YANG Qing-xi,SHI Shan-shuang,XU Hao,WAN Shu-de,LI Hong,LIU Wan-dong

2014, 34(4): 367-373.

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The strength of the vacuum vessel support structure of the reversed field pinch fusion experimental device (KTX) was analyzed by theoretical and finite element methods and then the support columns, bolt group and the annular were optimized based on the analysis results. The results of theoretical calculation and finite element analysis prove the reliability of the vacuum vessel support system (VVSS), and the optimized results also provide technical references for the implementation of the VVSS in KTX.

Measurement of electron density in the atmospheric pressure helium plasma jet by using a dielectric probe

QI Bing, ZHOU Qiu-jiao, PAN Li-zhu, ZHANG Meng-die, HUANG Jian-jun

2014, 34(4): 374-378.

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The electron densities in the atmospheric pressure helium plasma were calculated by means of electron drift velocity and the jet velocity respectively. The electron velocity and jet velocity can be calculated by means of helium plasma jet current measured by a dielectric probe and plasma discharge current signal measured by voltage probes. The results show that the estimated electron densities of the helium plasma jet calculated from electron drift velocity and the jet velocity are in the order of 10 ¹¹ cm^-3 and they increase with applied voltage. There is a little fluctuation in the value of the electron density along the jet axis of the plasma. This result is the same as the measured electron density in atmospheric pressure helium non-thermal plasma jet by using a Rogowski coil and a Langmuir probe. This is in one order lower than the electron density measured by microwave antenna.

Nuclear Fusion and Plasma Physics Vol.34 (2014)

2014, 34(4): 379-384.

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