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Experimental Study of the X-Ray Radiation Source at Approximately Constant Radiation Temperature

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Plasma Science and Technology 2013年第11期15卷 1108-1111页

作者：宋天明杨家敏杨冬李志超尚万里 Research center of Laser fusion China Academy of Engineering Physics

An X-ray radiation source with approximately constant radiation temperature is realized by irradiating golden hohlraum with a shaped laser pulse. A simple theoretical model based on power balance is used to design the shape of the drive laser pulse. Experiments are carried out on the Shenguang III prototype laser facility, and the experimentM results are presented for radiation sources with the flat-top lasting about 2.5 ns at two different peak temperatures of about 150 eV and 170 eV, respectively, including the the drive laser pulses and the time integrated possible improvements are discussed. time histories of the temperatures, the shapes of radiation spectra. The validity of the model and

关键词： X-ray radiation source laser pulse shaping power balance

Hundred-Joule-level,nanosecond-pulse Nd:glass laser system with high spatiotemporal beam quality

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High Power Laser Science and Engineering 2016年第1期4卷 63-74页

作者： Sensen Li Yulei Wang Zhiwei Lu Lei Ding Yi Chen Pengyuan Du Dexin Ba Zhenxing Zheng Xin Wang Hang Yuan Chengyu Zhu Weiming He Dianyang Lin Yongkang Dong Dengwang Zhou Zhenxu Bai Zhaohong Liu Can Cui National Key Laboratory of Science and Technology on Tunable Laser Harbin Institute of Technology Research center of Laser fusion China Academy of Engineering Physics

A 100-J-level Nd:glass laser system in nanosecond-scale pulse width has been constructed to perform as a standard source of high-fluence-laser science experiments. The laser system, operating with typical pulse durations of 3–5 ns and beam diameter 60 mm, employs a sequence of successive rod amplifiers to achieve 100-J-level energy at 1053 nm at3 ns. The frequency conversion can provide energy of 50-J level at 351 nm. In addition to the high stability of the energy output, the most valuable of the laser system is the high spatiotemporal beam quality of the output, which contains the uniform square pulse waveform, the uniform flat-top spatial fluence distribution and the uniform flat-top wavefront.

关键词： design frequency conversion laser amplifiers laser engineering laser systems light propagation modeling nonlinear optics optimization wavefront correction

Student Academic Performance Predictive Model Based on Dual-stream Deep Network

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计算机科学 2024年第10期51卷 119-128页

作者： XIE Hui ZHANG Pengyuan DONG Zexiao YANG Huiting KANG Huan HE Jiangshan CHEN Xueli center for Biomedical-photonics and Molecular Imaging Xi’an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life InformationSchool of Life Science and TechnologyXidian UniversityXi’an 710126China Engineering Research center of Molecular and Neuro Imaging Ministry of EducationXi’an 710126China Innovation center for Advanced Medical Imaging and Intelligent Medicine Guangzhou Institute of TechnologyXidian UniversityGuangzhou 510550China

Blended teaching is one of the essential teaching methods with the development of information *** a learning effect evaluation model is helpful to improve students’academic performance and helps teachers to better implement course ***,a lack of evaluation models for the fusion of temporal and non-temporal behavioral data leads to an unsatisfactory evaluation *** meet the demand for predicting students’academic performance through learning behavior data,this study proposes a learning effect evaluation method that integrates expert perspective indicators to predict academic performance by constructing a dual-stream network that combines temporal behavior data and non-temporal behavior data in the learning *** this paper,firstly,the Delphi method is used to analyze and process the course learning behavior data of students and establish an effective evaluation index system of learning behavior with universality;secondly,the Mann-Whitney U-test and the complex correlation analysis are used to analyze further and validate the evaluation indexes;and lastly,a dual-stream information fusion model,which combines temporal and non-temporal features,is *** learning effect evaluation model is built,and the results of the mean absolute error(MAE)and root mean square error(RMSE)indexes are 4.16 and 5.29,*** study indicates that combining expert perspectives for evaluation index selection and further fusing temporal and non-temporal behavioral features that for learning effect evaluation and prediction is rationality,accuracy,and effectiveness,which provides a powerful help for the practical application of learning effect evaluation and prediction.

关键词： Blended teaching Expert perspective indicators Two-stream information fusion model

Growth Mechanism of Vertically Aligned Carbon Nanotube Arrays

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： Ji-cheng Zhang Yong-jian Tang Yong Yi Min-jie Zhou Kang-fu Ma Wei-dong Wu Chao-yang Wang Science and Technology on Plasma Physics Laboratory Research Center of Laser Fusion China Academy of Engineering Physics Mianyang 621900 China College of Material Science and Engineering Southwest University of Science and TechnologyMianyang 621010 China

Vertically aligned multi-walled carbon nanotube arrays grown on quartz substrate are obtained by co-pyrolysis of xylene and ferrocene at 850 °C in a tube furnace. Raman spectroscopy and high resolution transmission electron microscopy measurements show that the single-walled carbon nanotubes are only present on top of vertically aligned multi-walled carbon nanotube arrays. It has been revealed that isolated single-walled carbon nanotubes are only present in those floating catalyst generated materials. It thus suggests that the single-walled carbon nanotubes here are also generated by floating catalyst. Vertically aligned carbon nanotube arrays on the quartz substrate have shown good orientation and good graphitization. Meanwhile, to investigate the growth mechanism, two bi-layers carbon nanotube films with different thickness have been synthesized and analyzed by Raman spectroscopy. The results show that the two-layer vertically aligned carbon nanotube films grow “bottom-up”. There are distinguished Raman scattering signals for the second layer itself, surface of the first layer, interface between the first and second layer, side wall and bottom surface. It indicates that the obtained carbon nanotubes follow the base-growth mechanism, and the single-walled carbon nanotubes grow from their base at the growth beginning when iron catalyst particles have small size. Those carbon nanotubes with few walls (typically <5 walls) have similar properties, which also agree with the base-growth mechanism.

关键词： Single-walled carbon nanotubes Multi-walled carbon nanotubes Growth mechanism Microstructure characterization

First experimental comparisons of laser-plasma interactions between spherical and cylindrical hohlraums at SGⅢ laser facility

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Matter and Radiation at Extremes 2017年第2期2卷 77-86页

作者： Yaohua Chen Zhichao Li Xufei Xie Chunyang Zheng Chuanlei Zhai Liang Hao Dong Yang Wenyi Huo Guoli Ren Jie Liu Xiaoshi Peng Tao Xu Yulong Li Sanwei Li Zhiwen Yang Liang Guo Lifei Hou Yonggang Liu Huiyue Wei Xiangming Liu Weiyi Cha Yukun Li Keli Deng Zheng Yuan Xiayu Zhan Haijun Zhang Baibin Jiang Wei Zhang Kai Du Xuewei Deng Yongkun Ding Xiaofeng Wei Wanguo Zheng Xiaodong Chen Xiantu He Ke Lan Institute of Applied Physics and Computational Mathematics Beijing100088China Research center of Laser fusion China Academy of Engineering PhysicsMianyang621900China center for Applied Physics and Technology Peking UniversityBeijing100871China Collaborative Innovation center of IFSA Shanghai Jiao Tong UniversityShanghai200240China

We present our recent laser-plasmas instability(LPI)comparison experiment at the SGIII laser facility between the spherical and cylindrical *** kinds of filling are considered:vacuum,gas-filling with or without a capsule inside.A spherical hohlraum of 3.6 mm in diameter,and a cylindrical hohlraum of 2.4 mm?4.3 mm are *** capsule diameter is 0.96 mm.A flat-top laser pulse with 3 ns duration and up to 92.73 kJ energy is *** experiment has shown that the LPI level in the spherical hohlraum is close to that of the outer beam in the cylindrical hohlraum,while much lower than that of the inner *** experiment is further simulated by using our 2-dimensional radiation hydrodynamic code LARED-Integration,and the laser back-scattering fraction and the stimulated Raman scatter(SRS)spectrum are post-processed by the high efficiency code of laser interaction with plasmas *** to the simulation,the plasma waves are strongly damped and the SRS is mainly developed at the plasma conditions of electron density from 0.08 n_(c) to 0.1 n_(c) and electron temperature from 1.5 keV to 2.0 keV inside the ***,obvious differences between the simulation and experiment are found,such as that the SRS back-scattering is underestimated,and the numerical SRS spectrum peaks at a larger wavelength and at a later time than the *** dif-ferences indicate that the development of a 3D radiation hydrodynamic code,with more accurate physics models,is mandatory for spherical hohlraum study.

关键词： Laser-plasmas interactions Spherical hohlraum Stimulated Raman scattering Stimulated Brillouin scattering

Effects of resonant magnetic perturbations on radial electric fields in DIII-D tokamak

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Plasma Science and Technology 2021年第10期23卷 137-149页

作者： Jingyuan FU Pengfei LIU Xishuo WEI Zhihong LIN Nathaniel Mandrachia FERRARO Raffi NAZIKIAN fusion Simulation center Peking UniversityBeijing 100871People's Republic of China Department of Physics and Astronomy University of CaliforniaIrvineCA 92697United States of America Princeton Plasma Physics Laboratory PrincetonNJ 08543United States of America

Gyrokinetic simulations of DIII-D tokamak equilibrium find that resonant magnetic perturbation(RMP)drives a neoclassical non-ambipolar electron particle flux,which causes a rapid change of equilibrium radial electric fields consistent with experimental observations during the suppression of the edge localized mode(ELM).The simulation results provide a support for the conjecture that RMP-induced changes of radial electric fields lead to the enhanced turbulent transport at the pedestal top during the ELM suppression(Taimourzadeh et al 2019 ***59046005).Furthermore,gyrokinetic simulations of collisionless damping of zonal flows show that resonant responses to the RMP decrease the residual level of the zonal flows and damp the geodesic acoustic mode.

关键词： resonant magnetic perturbation neoclassical transport zonal flow electric field

Toroidal component of velocity for geodesic acoustic modes in the edge plasmas of the J-TEXT tokamak

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Plasma Science and Technology 2021年第10期23卷 112-119页

作者： Yaoyu Xie Kaijun Zhao Zhipeng Chen Jiaqi Dong Kimitaka Itoh Zhongyong Chen Yuejiang Shi Yonghua Ding Jun Cheng Longwen Yan Hai Liu Zhifeng Cheng Zhoujun Yang Nengchao Wang Lu Wang Jianqiang Xu Yunfeng Liang J-TEXT Team School of Nuclear Science and Engineering East China University of TechnologyNanchang 330013People’s Republic of China International Joint Research Laboratory of Magnetic Confinement fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China Southwestern Institute of Physics Chengdu 610041People's Republic of China Institute of Science and Technology Research Chubu UniversityKasuga 816-8580Japan Research center for Plasma Turbulence Kyushu UniversityKyushu UniversityChubu UniversityAichi 487-8501Japan National Institute for fusion Science Toki 509-5292Japan ENN Science and Technology Development Co. Ltdand Hebei Key Laboratory of Compact FusionLangfang 065001People's Republic of China Institute of fusion Science School of Physical Science and TechnologySouthwest Jiaotong UniversityChengdu 610031People's Republic of China

The toroidal component of the velocity for geodesic acoustic modes(GAMs)is first *** Langmuir probe arrays set up near the top tokamak of the J-TEXT were utilized for this study.A significant peak at the GAM frequency is observed in Mach number *** toroidal velocity for the GAMs is estimated as 10–100 ms-1 and increases with the poloidal *** ratio of toroidal component to the poloidal one of the velocity is mainly located in the interval between 0.3 and *** higher safety factors q,the ratio almost does not change with decreasing the safety factor,whereas it goes up sharply at low *** coherencies between poloidal electric fields and Mach number fluctuations in turbulence frequency bands are also evaluated,and are higher than those between radial electric fields and Mach number fluctuations.

关键词： zonal flow geodesic acoustic mode tokamak return flow Mach number

Active coherent control of nanoscale light confinement：Modulation of plasmonic modes and position of hotspots for surface-enhanced Raman scattering detection

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Nano Research 2017年第9期10卷 2934-2943页

作者： Zhendong Zhu Qixia Wang Fa Zeng Oubo You Sitian Gao Benfeng Bai Qiaofeng Tan Guofan Jin Qunqing Li Shoushan Fan Wei Li Yushu Shi Xueshen Wang Division ofNano Metrology and Materials Measurement National Institute ofMetrology Beijing 100028 China State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instrument Tsinghua University Beijing 100084 China Tsinghua-Foxconn Nanotechnology Research center Tsinghua University Beijing 100084 China Laser fusion Research center China Academic of Engineering Physics Mianyang 621900 China

Multistep plasmonic nanostructures can induce the deep modulation of electromagnetic-field interactions on the nanoscale for positioning hotspots, and this generation of enhanced fields is important in many optical applications. In this article, a new strategy is proposed for fabricating a plasmonic doublestacked nanocone (DSC) nanostructure. In the DSC structure, a tunable plasmonic hybrid mode proceeds from the strong coupling of the plasmonic resonance of a fundamental cavity mode with a localized surface plasmon gap mode. In the nanostructure, the far-field response is deeply modulated and the hottest spots can be effectively positioned on the top surface of the DSC nanostructure. A controllable and cost-effective mask-reconfiguration technique for manufacturing the multiscale nanostructure is developed, which guarantees the generation of the introduced crucial stage on the DSC nanostructure. To evaluate the features of the plasmonic resonance, the DSC nanostructure is used as a surface-enhanced Raman scattering (SERS) substrate for detecting 4-mercaptopyridine molecules under specific excitation conditions. Its good performance, with an average measured SERS enhancement factor as high as 108, demonstrates its strong plasmonic-mode hybridization and extreme field enhancement.

关键词： surface plasmons mode hybridization positioning hotspot double-stacked nanocone (DSC) nanostructure surface-enhanced Raman scattering (SERS)

Unsteady state precipitation of M_(23)C_(6)carbides during thermal cycling in reduced activation steel manufactured by laser melting deposition

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Journal of Iron and Steel Research International 2023年第3期30卷 557-568页

作者： Ji-xin Hou Fu-lin Zhang Zhi-xin Xia Yun-he Yu Hai-ying Fu Shu-hai Huang Qian An Chi Zhang Shagang School of Iron and Steel Soochow UniversitySuzhou 215021JiangsuChina School of Material Science and Engineering Tsinghua UniversityBeijing 100084China center for fusion Science Southwestern Institute of PhysicsChengdu 610225SichuanChina Southwest Technology and Engineering Research Institute Chongqing 400050China

The temperature field distribution and thermal history of Fe-9Cr2WVTa reduced activation steel prepared by laser melting deposition(LMD)have been calculated with Gaussian and Ring laser beams,and the nucleation and growth behaviors of M_(23)C_(6)precipitates in the 1st,7th and 19th layers have been calculated using the modified classical nucleation theory and Svoboda Fischer Fratzl Kozeschnik *** energy distribution shows W-shape with Ring laser beam while it shows V-shape with Gaussian laser beam,which results in the more uniform M_(23)C_(6)size in the same layer with Ring laser *** in the bottom(i.e.,the 1st layer)have the minimum size and the size increases with the layer number with Gaussian and Ring laser *** temperature history,the instantaneous nucleation rate and the size evolution of M_(23)C_(6)have been systematically *** results indicate that the nucleation,growth and re-dissolution of precipitates in reduced activation steel depend on the amount of energy absorbed in the thermal cycle during *** continuous accumulation of energy during the thermal cycle leads to larger M_(23)C_(6)at the top *** unsteady state precipitation dynamics of M_(23)C_(6)carbides during thermal cycling are consistent with the simulation results.

关键词： Laser melting deposition Reduced activation steel Unsteady state precipitation Heat source model