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Stimulated Raman scattering in a non-eigenmode regime

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High Power Laser Science and Engineering 2020年第2期8卷 80-87页

作者： Yao Zhao Suming Weng zhengming sheng Jianqiang Zhu Key Laboratory of High Power Laser and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China 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 SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUK

Stimulated Raman scattering(SRS)in plasma in a non-eigenmode regime is studied theoretically and *** from normal SRS with the eigen electrostatic mode excited,the non-eigenmode SRS is developed at plasma density ne>0.25nc when the laser amplitude is larger than a certain *** satisfy the phase-matching conditions of frequency and wavenumber,the excited electrostatic mode has a constant frequency around half of the incident light frequency ω0/2,which is no longer the eigenmode of electron plasma wave ω*** the scattered light and the electrostatic wave are trapped in plasma with their group velocities being ***-hot electrons are produced by the non-eigen electrostatic *** theoretical model is validated by particle-in-cell *** SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than 10^15 W/cm^2.

关键词： hot electrons laser plasma interactions stimulated Raman scattering

Two-stage acceleration of interstellar ions driven by high-energy lepton plasma flows

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Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 76-80页

作者： CUI YunQian sheng zhengming LU QuanMing LI YuTong ZHANG Jie Beijing National Laboratory of Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Scottish Universities Physics Alliance Department of Physics University of Strathclyde Key Laboratory for Laser Plasmas (Mo E) and Department of Physics and Astronomy Shanghai Jiao Tong University IFSA Collaborative Innovation Center Shanghai Jiao Tong University School of Earth and Space Sciences University of Science and Technology of China

We present the particle-in-cell(PIC) simulation results of the interaction of a high-energy lepton plasma flow with background electron-proton plasma and focus on the acceleration processes of the protons. It is found that the acceleration follows a two-stage process. In the first stage, protons are significantly accelerated transversely(perpendicular to the lepton flow) by the turbulent magnetic field "islands" generated via the strong Weibel-type instabilities. The accelerated protons shows a perfect inverse-power energy spectrum. As the interaction continues, a shockwave structure forms and the protons in front of the shockwave are reflected at twice of the shock speed, resulting in a quasi-monoenergetic peak located near 200 Me V under the simulation parameters. The presented scenario of ion acceleration may be relevant to cosmic-ray generation in some astrophysical environments.

关键词： particle acceleration Fermi acceleration collisionless shock lepton plasma flow

Particle-in-cell/Monte Carlo simulation of filamentary barrier discharges

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Plasma Science and Technology 2017年第11期19卷 6-11页

作者： Weili FAN zhengming sheng Fucheng LIU Key Laboratory for Laser Plasmas(MoE)and Department of Physics Shanghai Jiao Tong UniversityShanghai 200240People's Republic of China Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghai 200240People's Republic of China College of Physics Science and Technology Hebei UniversityBaoding 071002People's Republic of China SUPA Department of PhysicsUniversity of StrathclydeGlasgow G4 0NGUnited Kingdom

The plasma behavior of filamentary barrier discharges in helium is simulated using a twodimensional（2D） particle-in-cell/Monte Carlo model. Four different phases have been suggested in terms of the development of the discharge： the Townsend phase; the space-charge dominated phase; the formation of the cathode layer, and the extinguishing phase. The spatialtemporal evolution of the particle densities, velocities of the charged particles, electric fields, and surface charges has been demonstrated. Our simulation provides insights into the underlying mechanism of the discharge and explains many dynamical behaviors of dielectric barrier discharge（DBD） filaments.

关键词： dielectric barrier discharge filamentary discharge particle-in-cell/Monte Carlo simulation

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

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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

Initial Evolution of a Laser Wake-Field in Plasmas

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Chinese Physics Letters 1993年第1期10卷 25-28页

作者： sheng zhengming MA Jinxiu YU Wei XU Zhizhan Shanghai Institute of Optics and Fine Mechanics Academia SinicaShanghai 201800

Numerical calculations are used to study the initial temporal evolution of the wake-field produced by a short laser *** are compared to the previous quasi-static *** usually adopted quasi-static approximation is found... 详细信息

关键词： Evolution approximation Plasma

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

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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

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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

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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

Preface to Special Topic: Extreme High-Field Physics Driven by Lasers

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Matter and Radiation at Extremes 2019年第6期4卷 63-64页

作者： zhengming sheng Bjorn Manuel Hegelich Stefan Weber Yan Yin Shanghai Jiao Tong University ShanghaiChina and University of StrathclydeGlasgowUnited Kingdom University of Texas at Austin AustinTexas 78712USA ELI-Beamlines Institute of PhysicsAcademy of Sciences of the Czech RepublicPragueCzech Republic Department of Physics National University of Defense TechnologyChangshaChina

With the continuous development of high power laser technologies,lasers with peak power at 10 petawatt(PW)or above are becoming available soon in a few laboratories *** lasers may be focused to an intensity above 1023 W/cm2,at which heavy elements such as uranium can be stripped of electrons,entirely leaving behind pure atomic nuclei,and electrons can be accelerated to more than 10 *** are entering an unprecedented regime of laser-matter interactions,where collective effects,relativistic effects,and quantum electrodynamic(QED)effects all play significant *** rich nonlinear physics in this regime could be tested experimentally,such as radiation reaction,gamma-ray and pair production via different processes,laser driven nuclear physics,laser-vacuum polarization,*** is expected that the new understanding of physics for these extreme high field conditions will lead to a wide range of applications.

关键词： polarization regime collective