检索结果-南通市图书馆

Proton acceleration in plasma turbulence driven by high-energy lepton jets

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第11期33卷 98-105页

作者： Gaowei Zhang Zhengming Sheng suming weng Min Chen Jie Zhang Key Laboratory for Laser Plasmas (MOE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 201210China

The interaction of high energy lepton jets composed of electrons and positrons with background electron–proton plasma is investigated numerically based upon particle-in-cell simulation,focusing on the acceleration processes of background protons due to the development of electromagnetic *** interaction may be found in the universe when energetic lepton jets propagate in the interstellar *** such a jet is injected into the background plasma,theWeibel instability is excited quickly,which leads to the development of plasma turbulence into the nonlinear *** turbulent electric and magnetic fields accelerate plasma particles via the Fermi II type acceleration,where the maximum energy of both electrons and protons can be accelerated to much higher than that of the incident jet *** of background plasma acceleration,a collisionless electrostatic shock wave is formed,where some pre-accelerated protons are further accelerated when passing through the shock wave *** of proton acceleration on the beam-plasma density ratio and beam energy is *** a given background plasma density,the maximum proton energy generally increases both with the density and kinetic energy of the injected ***,for a homogeneous background plasma,the proton acceleration via both turbulent fields and collisionless shocks is found to be *** the case of an inhomogeneous plasma,the proton acceleration in the plasma turbulence is *** studies illustrate a scenario where protons from background plasma can be accelerated successively by the turbulent fields and collisionless shocks.

关键词： Weibel instability turbulence collisionless shock ion acceleration

Magnetic field annihilation and reconnection driven by femtosecond lasers in inhomogeneous plasma

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2017年第11期60卷 68-75页

作者： YouYuan Wang FeiYu Li Min Chen suming weng QuanMing Lu QuanLi Dong ZhengMing Sheng Jie Zhang Key Laboratory for Laser Plasmas (Ministry of Education) and School of Physics and Astronomy Shanghai Jiao Tong University Collaborative Innovation Center of IFSA (CICIFSA) Shanghai Jiao Tong University Scottish Universities Physics Alliance (SUPA) Department of PhysicsUniversity of Strathclyde Key Lab of Geospace Environment Chinese Academy of Sciences Department of Geophysics and Planetary Science University of Science and Technology of China School of Physics and Optoelectronic Engineering Ludong University

The process of fast magnetic reconnection driven by intense ultra-short laser pulses in underdense plasma is investigated by particle-in-cell simulations. In the wakefield of such laser pulses, quasi-static magnetic fields at a few mega-Gauss are generated due to nonvanishing cross product ▽(n/) × p. Excited in an inhomogeneous plasma of decreasing density, the quasi-static magnetic field structure is shown to drift quickly both in lateral and longitudinal directions. When two parallel-propagating laser pulses with close focal spot separation are used, such field drifts can develop into magnetic reconnection(annihilation) in their overlapping region, resulting in the conversion of magnetic energy to kinetic energy of particles. The reconnection rate is found to be much higher than the value obtained in the Hall magnetic reconnection model. Our work proposes a potential way to study magnetic reconnection-related physics with short-pulse lasers of terawatt peak power only.

关键词： magnetic reconnection laser wakefield magnetic field generation

Nonlocal thermal transport in magnetized plasma along different directions

在线全文

学校读者我要写书评

暂无评论

Matter and Radiation at Extremes 2022年第4期7卷 30-39页

作者： Hanzhi Zhao Zhengming Sheng suming weng Key Laboratory for Laser Plasmas(MoE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

Nonlocal thermal transport in magnetized plasmas is studied theoretically and numerically with the Vlasov–Fokker–Planck(VFP)model,in which the magnetic field has nonzero components both perpendicular to and along the temperature *** heat transport is found in both the longitudinal and transverse directions,provided the temperature gradients are sufficiently *** magnetic field tends to reduce the nonlocality of the thermal transport in the direction perpendicular to the magnetic field,i.e.,the difference between the heat fluxes predicted by the Braginskii theory and the VFP simulation decreases with increasing magnetic field *** the initial temperature gradient is steep,the nonlocal heat flux depends not only on the present temperature profile,but also on its time ***,the contribution of high-order terms in the spherical harmonic expansion of the electron distribution function becomes important for a magnetized plasma,in particular for thermal transport in the direction perpendicular to the temperature gradient.

关键词： VFP directions thermal

Absolute instability modes due to rescattering of stimulated Raman scattering in a large nonuniform plasma

在线全文

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2019年第1期7卷 144-153页

作者： Yao Zhao Zhengming Sheng suming weng Shengzhe Ji Jianqiang Zhu Key Laboratory of High Power Laser and Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Key Laboratory for Laser Plasmas (MoE) School of Physics and Astronomy Shanghai Jiao Tong University Collaborative Innovation Center of IFSA (CICIFSA) Shanghai Jiao Tong University SUPA Department of Physics University of Strathclyde Tsung-Dao Lee Institute Shanghai Jiao Tong University University of Chinese Academy of Sciences

Absolute instability modes due to secondary scattering of stimulated Raman scattering (SRS) in a large nonuniform plasma are studied theoretically and numerically. The backscattered light of convective SRS can be considered as a pump light with a finite bandwidth. The different frequency components of the backscattered light can be coupled to develop absolute SRS instability near their quarter-critical densities via rescattering process. The absolute SRS mode develops a Langmuir wave with a high phase velocity of about c/■ with c the light speed in vacuum. Given that most electrons are at low velocities in the linear stage, the absolute SRS mode grows with very weak Landau damping. When the interaction evolves into the nonlinear regime, the Langmuir wave can heat abundant electrons up to a few hundred ke V via the SRS rescattering. Our theoretical model is validated by particle-in-cell simulations. The absolute instabilities may play a considerable role in the experiments of inertial confinement fusion.

关键词： laser plasma interactions stimulated Raman scattering two plasmon decay instability hot electron

Stimulated Raman scattering excited by incoherent light in plasma

在线全文

学校读者我要写书评

暂无评论

Matter and Radiation at Extremes 2017年第4期2卷 190-196页

作者： Yao Zhao suming weng Min Chen Jun Zheng Hongbin Zhuo Zhengming Sheng Key Laboratory for Laser Plasmas(MoE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghai 200240China College of Science National University of Defense TechnologyChangsha 410073China SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUK

Stimulated Raman scattering(SRS)excited by incoherent light is studied via particle-in-cell *** is shown that a large bandwidth of incoherent light can reduce the growth of SRS and electron heating considerably in the linear ***,different components of the incoherent light can be coupled by the Langmuir waves,so that stimulated Raman backward scattering can *** the bandwidth of incoherent light is larger than the Langmuir wave frequency,forward SRS can be seeded between different components of the incoherent *** incoherent light can only increase the time duration for nonlinear saturation but cannot diminish the saturation level obviously.

关键词： Stimulated Raman scattering Instability suppression Incoherent light Inertial confinement fusion

Effects of second-order dispersion of ultrashort laser pulse on stimulated Raman scattering

在线全文

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2022年第6期10卷 41-48页

作者： Yanqing Deng Dongning Yue Mufei Luo Xu Zhao Yaojun Li Xulei Ge Feng Liu suming weng Min Chen Xiaohui Yuan Jie Zhang Key Laboratory for Laser Plasmas(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghaiChina

The influence of second-order dispersion(SOD)on stimulated Raman scattering(SRS)in the interaction of an ultrashort intense laser with plasma was *** significant backward SRS was observed with the increase of the absolute value of SOD(|ψ2|).The integrated intensity of the scattered light is positively correlated to the driver laser pulse *** by the side SRS,filaments with different angles along the laser propagation direction were observed in the transverse shadowgraph.A model incorporating Landau damping and above-threshold ionization was developed to explain the SOD-dependent angular distribution of the filaments.

关键词： second-order dispersion stimulated Raman scattering ultrashort intense laser

Compact ultrafast neutron sources via bulk acceleration of deuteron ions in an optical trap

在线全文

学校读者我要写书评

暂无评论

Matter and Radiation at Extremes 2024年第5期9卷 22-31页

作者： Zhiyu Lei Hanghang Ma Xiaobo Zhang Lin Yu Yihang Zhang Yutong Li suming weng Min Chen Jie Zhang Zhengming Sheng Key Laboratory for Laser Plasmas and School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Centre of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 201210China College of Physics and Electronics Engineering Northwest Normal UniversityLanzhou 730070China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

A scheme for a quasi-monoenergetic high-flux neutron source with femtosecond duration and highly anisotropic angular distribution is *** scheme is based on bulk acceleration of deuteron ions in an optical trap or density grating formed by two counter-propagating laser pulses at an intensity of-10^(16)W~cm^(2)in a near-critical-density *** deuterons are first pre-accelerated to an energy of tens of keV in the ambipolar fields formed in the optical *** energy is boosted to the MeV level by another one or two laser pulses at an intensity of-10^(20)W~cm^(2),enabling fusion reactions to be triggered with high *** contrast to previously proposed pitcher–catcher configurations,our scheme can provide spatially periodic acceleration structures and effective collisions between deuterons inside the whole target ***,neutrons are generated directly inside the optical *** simulations show that neutron pulses with energy 2–8 MeV,yield 10^(18)–10^(19)n/s,and total number 106–107 in a duration-400 fs can be obtained with a 25μm ***,the neutron pulses exhibit unique angularly dependent energy spectra and flux distributions,predominantly along the axis of the energy-boosting *** microsize femtosecond neutron pulses may find many applications,such as high-resolution fast neutron imaging and nuclear physics research.

关键词： acceleration scheme angular

等离子体中Fokker-Planck方程的有限元模拟

在线全文

学校读者我要写书评

暂无评论

计算物理 2007年第2期24卷 134-140页

作者：翁苏明盛政明中国科学院物理研究所光物理实验室北京100080

利用有限元方法设计了一套相对简单明了的求解Fokker-Planck方程的方案.这个方案不必严格限制计算格点的步长和时间步长,就可以确保分布函数的非负性和粒子数的守恒.通过一维程序模拟,进一步证实了这个方案的可靠性.对于多维问题的分析... 详细信息

利用有限元方法设计了一套相对简单明了的求解Fokker-Planck方程的方案.这个方案不必严格限制计算格点的步长和时间步长,就可以确保分布函数的非负性和粒子数的守恒.通过一维程序模拟,进一步证实了这个方案的可靠性.对于多维问题的分析和一维问题完全一样,所以非常容易将其推广到多维问题.

关键词： Fokker-Planck方程有限元方法等离子体 Legendre展开式

激光带宽对等离子体中受激拉曼散射不稳定性的抑制效应

在线全文

学校读者我要写书评

暂无评论

中国科学：物理学、力学、天文学 2015年第3期45卷 59-68页

作者：赵耀郑君於陆勒陈民翁苏明盛政明上海交通大学物理与天文系激光等离子体教育部重点实验室上海200240

本文研究了激光带宽对等离子体中受激拉曼散射不稳定性激发的抑制效应.通过改变激光参数和等离子体参数,利用一维粒子模拟验证了当激光带宽远大于线性增长率时,带宽对受激拉曼散射的线性增长阶段具有明显的抑制作用.模拟研究同时表明通... 详细信息

本文研究了激光带宽对等离子体中受激拉曼散射不稳定性激发的抑制效应.通过改变激光参数和等离子体参数,利用一维粒子模拟验证了当激光带宽远大于线性增长率时,带宽对受激拉曼散射的线性增长阶段具有明显的抑制作用.模拟研究同时表明通过选择适当的调频参数和降低受激拉曼散射的线性增长率可以使带宽的抑制效应更明显.但是激光带宽并没有使受激拉曼散射完全消失,其抑制作用主要体现在延长不稳定性线性增长的时间.

关键词：受激拉曼散射激光带宽惯性约束核聚变参量不稳定