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First-principles calculations of K-shell x-ray absorption spectra for warm dense ammonia

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Chinese Physics B 2021年第5期30卷 576-582页

作者： Zi Li Wei-Jie Li Cong Wang Dafang Li Wei Kang xian-tu he Ping Zhang Institute of Applied Physics and Computational Mathematics Beijing 100088China Center for Applied Physics and Technology Peking UniversityBeijing 100871China

The x-ray absorption spectroscopy is a powerful tool for the detection of thermodynamic conditions and atomic structures on warm dense ***,we perform first-principles molecular dynamics and x-ray absorption spectrum calculations for warm dense ammonia,which is one of the major constituents of Uranus and *** nitrogen K-shell x-ray absorption spectrum(XAS)is determined along the Hugoniot curve,and it is found that the XAS is a good indicator of the prevailing thermodynamic *** atomic structures at these conditions are *** indicate that the ammonia could dissociate to NH_(x)(x=0,1,or 2)fragments and form nitrogen clusters,and the ratios of these products change with varying *** contributions to the XAS from these products show quite different characteristics,inducing the significant change of XAS along the Hugoniot *** model simulations imply that the distribution of the peak position of atomic XAS is the dominant factor affecting the total XAS.

关键词： first-principles warm dense x-ray absorption spectrum ammonia

Review of the current status of fast ignition research atthe IAPCM

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High Power Laser Science and Engineering 2014年第1期2卷 4-12页

作者： Hong-bo Cai Si-zhong Wu Jun-feng Wu Mo Chen Hua Zhang Min-qing he Li-hua Cao Cang-tao Zhou Shao-ping Zhu xian-tu he Institute of Applied Physics and Computational Mathematics Center for Applied Physics and Technology Peking University

We review the present status and future prospects of fast ignition(FI) research of the theoretical group at the IAPCM(Institute of Applied Physics and Computational Mathematics, Beijing) as a part of the inertial confinement fusion project. Since the approval of the FI project at the IAPCM, we have devoted our efforts to improving the integrated codes for FI and designing advanced targets together with the experimental group. Recent FI experiments [K. U. Akli et al., Phys. Rev. E 86, 065402(2012)] showed that the petawatt laser beam energy was not efficiently converted into the compressed core because of the beam divergence of relativistic electron beams. The coupling efficiency can be improved in three ways:(1) using a cone–wire-in-shell advanced target to enhance the transport efficiency,(2) using external magnetic fields to collimate fast electrons, and(3) reducing the prepulse level of the petawatt laser beam. The integrated codes for FI, named ICFI, including a radiation hydrodynamic code, a particle-in-cell(PIC) simulation code,and a hybrid fluid–PIC code, have been developed to design this advanced target at the IAPCM. The Shenguang-II upgraded laser facility has been constructed for FI research; it consists of eight beams(in total 24 kJ/3ω, 3 ns) for implosion compression, and a heating laser beam(0.5–1 kJ, 3–5 ps) for generating the relativistic electron beam. A fully integrated FI experiment is scheduled for the 2014 project.

关键词： fast ignition integrated simulation codes

Simulation of the Weakly Nonlinear Rayleigh–Taylor Instability in Spherical Geometry

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Chinese Physics Letters 2020年第5期37卷 73-76页

作者： Yun-Peng Yang Jing Zhang Zhi-Yuan Li Li-Feng Wang Jun-Feng Wu Wen-Hua Ye xian-tu he School of Physics Peking UniversityBeijing 100871 Center for Applied Physics and Technology HEDPSPeking UniversityBeijing 100871 Institute of Applied Physics and Computational Mathematics Bejing 100094

The Rayleigh-Taylor instability at the weakly nonlinear(WN)stage in spherical geometry is studied by numerical *** mode coupling processes are *** results are consistent with the WN model based on parameter expansion,while higher order effects are found to be *** Legendre mode perturbation Pn(cos B),the nonlinear saturation amplitude(NSA)of the fundamental mode decreases with the mode number *** n is large,the spherical NSA is lower than the corresponding planar ***,for large n,the planar NSA can be recovered by applying Fourier transformation to the bubble/spike near the equator and calculating the NSA of the converted trigonometric harmonic.

关键词： planar spherical negligible

Interface Width Effect on the Weakly Nonlinear Rayleigh–Taylor Instability in Spherical Geometry

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Chinese Physics Letters 2020年第7期37卷 43-46页

作者： Yun-Peng Yang Jing Zhang Zhi-Yuan Li Li-Feng Wang Jun-Feng Wu Wun-Hua Ye xian-tu he School of Physics Peking UniversityBeijing 100871China Center for Applied Physics and Technology HEDPSand College of EngineeringPeking UniversityBeijing 100871China Institute of Applied Physics and Computational Mathematics Beijing 100094China

Interface width effect on the spherical Rayleigh–Taylor instability in the weakly nonlinear regime is studied by numerical *** Legendre perturbation mode Pn with wave number Kn and interface half-width L,the commonly adopted empirical linear growth rate formulaγnem(L)=γn/√1+KnL is found to be sufficient in spherical *** the weakly nonlinear stage,the interface width affects the mode coupling *** development of the mode P2n is substantially influenced by the interface ***,the nonlinear saturation amplitude increases with the interface width.

关键词： interface nonlinear weakly

Ab Initio Simulations of Dense helium Plasmas

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Ab Initio Simulations of Dense Helium Plasmas

Recent progress of laser driven particle acceleration at Peking University

第七届全国青年计算物理学术会议

作者： Cong Wang xian-tu he Ping Zhang LCP Institute of Applied Physics and Computational Mathematics Center for Applied Physics and Technology Peking University

We study the thermophysical properties of dense helium plasmas by using quantum molecular dynamics and orbital-free molecular dynamics simulations, where densities are considered from 400 to 800 g/cm3and temperatures up to 800 eV. Results are presented for the equation of state. From the KuboGreenwood formula, we derive the electrical conductivity and electronic thermal conductivity. In particular, with the increase in temperature, we discuss the change in the Lorenz number, which indicates a transition from strong coupling and degenerate state to moderate coupling and partial degeneracy regime for dense helium.

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来源： cnki会议评论

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Frontiers of physics 2013年第5期8卷 577-584页

作者： Xue-Qing Yan Chen Lin Hai-Yang Lu Kun Zhu Yu-Bin Zou Hong-Yong Wang Bing Liu Shuan Zhao Jiao Zhu Yi-Xing Geng, he-Zheng Fu Yong Shang Chao Cao Yin-Ren Shou Wei Song Yuan-Rong Lu Zhong-Xi Yuan Zhi-Yu Guo xian-tu he Jia-Er Chen State Key Laboratory of Nuclear Physics and Technology and CAPT Peking University Beijing 100871 China

Recently, radiation pressure acceleration （RPA） has been proposed and extensively studied, which shows that circularly polarized （CP） laser pulses can accelerate mono-energetic ion bunches in a phase-stable-acceleration （PSA） way from ultrathin foils. It is found that self-orgizing proton beam can be stably accelerated to GeV in the interaction of a CP laser with a planar target at 1022 W/cm2. A project called Compact LAser Plasma proton Accelerator （CLAPA） is approved by MOST in China recently. A prototype of laser driven proton accelerator （1 to 15 MeV/1 Hz） based on the PSA mechanism and plasma lens is going to be built at Peking University in the next five years. It will be upgraded to 200 MeV later for applications such as cancer therapy, plasma imaging and fast ignitiou for inertial confine fusion.

关键词： phase-stable acceleration (PSA) laser ion acceleration ignition

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掘锚一体化技术在煤巷的应用

陕西煤炭 2011年第3期30卷 104-106页

作者：高振周涂显赫神华神东煤炭集团公司万利一矿内蒙古鄂尔多斯017000

介绍了掘锚机组在万利一矿的试用情况,对掘锚一体化快速成巷技术在煤巷掘进中的应用,以及掘锚机组作业线的问题,进行了分析并提出相应对策。

关键词：巷道快速掘进掘锚机组安全高效矿井

Preface The 8th International Conference on Computational Physics (ICCP8)

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Communications in Computational Physics 2014年第4期15卷 I0001-I0001页

作者： xian-tu he Song Jiang Tao Tang Hong Kong Baptist University

The International Conference on Computational Physics(ICCP)is a series of the conference organized by the Institute of Applied Physics and Computational Mathematics(IAPCM).The 7th of this series was help in Beijing from May 17 to 20,2010,and the 8th ICCP8 was held in Hong Kong on 7-11 January,*** ICCP8 is organized by the IAPCM and Hong Kong Baptist University(HKBU).The conference aims to bring together researchers,scientists,engineers,and students to exchange and stimulate ideas from different disciplines,to discuss the practical challenges encountered and the solutions adopted,and to learn about the recent developments in frontiers of theory and numerical methods in computational physics.

关键词： ICCP frontier organized

Characterization of Pattern Formation from Modulation Instability in the Cubic Schrodinger Equation

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Chinese Physics Letters 1998年第9期15卷 659-661页

作者： LONG Tao he xian-tu Graduate School China Academy of Engineering PhysicsBeijing 100088 Institute of Applied Physics and Computational Mathematics Beijing 100088 Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100080

The study of pattern dynamics in a Hamiltonian system(HS)having an infinite number of degree of freedom is very difficult due to the absence of attractors in such *** this letter,we propose a useful method that only a few representative manifolds in phase space are investigated,and it can be used to reveal the pattern formation of *** conserved cubic Schrödinger equation is *** a special model is chosen,this method can be applied to more general case such as the near-integrable HS.

关键词： integrable letter infinite