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Electromagnetic radiation from laser wakefields in underdense plasma

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High Power Laser Science and Engineering 2014年第1期2卷 29-33页

作者： Yue Liu Wei-Min Wang zheng-ming sheng Key Laboratory for Laser Plasmas (MoE) and Department of Physics and Astronomy Shanghai Jiao Tong University Beijing National Laboratory of Condensed Matter Physics Institute of Physics CAS Department of Physics SUPA Strathclyde University

It is demonstrated by simulations and analysis that a wakefield driven by an ultrashort intense laser pulse in underdense plasma can emit tunable electromagnetic radiation along the laser propagation direction. The profile of such a kind of radiation is closely associated with the structure of the laser wakefield. In general, electromagnetic radiation in the terahertz range with its frequency a few times the electron plasma frequency can be generated in the moderate intensity regime. In the highly nonlinear case, a chain of radiation pulses is formed corresponding to the nonlinear structure of the wake. Study shows that the radiation is associated with the self-modulation process of the laser pulse in the wakefield and resulting transverse electron momenta from modulated asymmetric laser fields.

关键词： laser wakefield PIC simulation tunable radiation transverse momentum

Vlasov-Fokker-Planck Simulations for High-Power Laser-Plasma Interactions

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Communications in Computational Physics 2012年第4期11卷 1236-1260页

作者： Su-ming Weng zheng-ming sheng Hui Xu Jie Zhang Beijing National Laboratory of Condensed Matter Physics Institute of PhysicsCASBeijing 100190China Key Laboratory for Laser Plasmas(MoE)and Department of Physics Shanghai Jiaotong UniversityShanghai 200240China Theoretical Quantum Electronics(TQE) Technische Universit¨at DarmstadtD-64289 DarmstadtGermany Shandong Provincial Key Laboratory of Laser Polarization and Information Technology Department of PhysicsQufu Normal UniversityQufu 273165China

A review is presented on our recent Vlasov-Fokker-Planck(VFP)simulation code development and applications for high-power laser-plasma *** schemes are described for solving the kinetic VFP equation with both electronelectron and electron-ion collisions in one-spatial and two-velocity(1D2V)*** are based on the positive and flux conservation method and the finite volume method,and these twomethods can insure the particle number *** simulation code can deal with problems in high-power laser/beam-plasma interactions,where highly non-Maxwellian electron distribution functions usually develop and the widely-used perturbation theories with the weak anisotropy assumption of the electron distribution function are no longer in *** present some new results on three typical problems:firstly the plasma current generation in strong direct current electric fields beyond Spitzer-H¨arm’s transport theory,secondly the inverse bremsstrahlung absorption at high laser intensity beyond Langdon’s theory,and thirdly the heat transport with steep temperature and/or density gradients in laser-produced ***,numerical parameters,performance,the particle number conservation,and the energy conservation in these simulations are provided.

关键词： Vlasov-Fokker-Planck equation electric conductivity inverse bremsstrahlung nonlocal heat transport positive and flux conservation method finite volume method

Modeling of Bound Electron Effects in Particle-in-Cell

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Communications in Computational Physics 2022年第7期32卷 583-594页

作者： Xiangyan An Min Chen zheng-ming sheng 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 200240China

To include the bound electron effects in particle-in-cell(PIC)simulation,we propose a model in which the response of the dipole components of partially ionized ions to external electromagnetic fields can be *** of treating the macroion particle as a single particle without an internal structure,the ions are considered to have a structure composed of a central nucleus and a bounded electron cloud in our *** two parts experience the interactions of both the external electromagnetic fields and the internal Coulomb *** this way,the laser scattering effects by a partially ionized medium can be modeled properly in the PIC *** laser propagation in a neutral medium and the Bragg scattering of the laser in crystal structure have been simulated with a PIC code modified based on our model as the *** model may find applications to study some interesting problems,such as the x-ray laser-driven wakefield acceleration in crystals,the x-ray laser-driven high energy density physics,and intense laser propagation in partially ionized nonlinear optical materials,etc.

关键词： Particle-in-cell simulation bound electrons x-rays crystals

Tunable synchrotron-like radiation from centimeter scale plasma channels

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Light(Science & Applications) 2016年第1期5卷 819-825页

作者： Min Chen Ji Luo Fei-Yu Li Feng Liu zheng-ming sheng Jie Zhang Key Laboratory for Laser Plasmas(MOE) Department 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

Synchrotron radiation(SR)sources are immensely useful tools for scientific researches and many practical ***,the state-of-the-art synchrotrons rely on conventional accelerators,where electrons are accelerated in a straight line and radiate in bending magnets or other insertion ***,these facilities are usually large and ***,we study a compact all optical synchrotron-like radiation source based on laser-plasma acceleration either in a straight or a curved plasma *** the laser pulse off-axially injected,its centroid oscillates transversely in the plasma *** results in a wiggler motion of the whole accelerating structure and the self-trapped electrons behind the laser pulse,leading to strong synchrotron-like radiations with tunable *** is further shown that a palmtop ring-shaped synchrotron is possible with current high power laser *** its potential of high flexibility and tunability,such light sources once realized would find applications in wide areas and make up the shortage of large SR facilities.

关键词： laser guiding laser wakefield acceleration synchrotron radiation

Simulation of High Power THz Emission from Laser Interaction with Tenuous Plasma and Gas Targets

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Communications in Computational Physics 2008年第10期4卷 1258-1278页

作者： zheng-ming sheng Hui-Chun Wu Wei-MinWang Min Chen Xiao-Gang Dong Jun zheng Jie Zhang Department of Physics Shanghai Jiao Tong UniversityShanghai 200240China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsCASBeijing 100190China Max-Planck-Institut f¨ur Quanenoptik D-85748 GarchingGermany

With one-and two-dimensional particle-in-cell(PIC)codes,we simulate the generation of high power terahertz(THz)emission from the interaction of ultrashort intense lasers with tenuous plasma and gas *** driving high-amplitude electron plasma waves either with a laser wakefield or the beatwave of two laser pulses,powerful THz electromagnetic pulses can be produced by linear mode conversion in inhomogeneous plasma or by the transient current induced at the surfaces of a thin plasma layer of few plasma *** with incident lasers at moderate intensity such as 1017W/cm2,the produced emission can be at the level of tens of MW in power and capable of affording field strengths of a few MV/cm,suitable for the studies of THz nonlinear *** field ionization included in the PIC codes,THz emission from laser interaction with tenuous gas targets is *** is found that the transient transverse current formed during the ionization processes is responsible for the THz *** this mechanism,onemay also obtain THz fields ofMV/cm at lower laser intensity as compared with the schemes of plasma-wave excitation.

关键词： Particle-in-cell simulation laser-plasma electron plasma wave high power THz emission

Generation of single-cycle relativistic infrared pulses at wavelengths above 20 μm from density-tailored plasmas

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Matter and Radiation at Extremes 2022年第1期7卷 29-34页

作者： Xing-Long Zhu Wei-Yuan Liu Su-ming Weng Min Chen zheng-ming sheng Jie Zhang Key Laboratory for Laser Plasmas(MOE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUnited Kingdom

Ultra-intense short-pulse light sources are powerful tools for a wide range of ***,relativistic short-pulse lasers are normally generated in the near-infrared ***,we present a promising and efficient way to generate tunable relativistic ultrashort pulses with wavelengths above 20μm in a density-tailored *** this approach,in the first stage,an intense drive laser first excites a nonlinear wake in an underdense plasma,and its photon frequency is then downshifted via phase modulation as it propagates in the plasma ***,in the second stage,the drive pulse enters a lower-density plasma region so that the wake has a larger plasma cavity in which longer-wavelength infrared pulses can be *** simulations show that the resulting near-single-cycle pulses cover a broad spectral range of 10–40μm with a conversion efficiency of∼2.1%(∼34 mJ pulse energy).This enables the investigation of nonlinear infrared optics in the relativistic regime and offers new possibilities for the investigation of ultrafast phenomena and physics in strong fields.

关键词： relativistic regime intense

Post-solitons and electron vortices generated by femtosecond intense laser interacting with uniform near-critical-density plasmas

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Chinese Physics B 2022年第4期31卷 486-492页

作者： Dong-Ning Yue Min Chen Yao Zhao Pan-Fei Geng Xiao-Hui Yuan Quan-Li Dong zheng-ming sheng Jie Zhang School of Sciences Harbin Institute of Technology at WeihaiWeihai 264209China Key Laboratory for Laser Plasmas(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of High Power Laser and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Tsung-Dao Lee Institute Shanghai 200240China

Generation of nonlinear structures,such as stimulated Raman side scattering waves,post-solitons and electron vortices,during ultra-short intense laser pulse transportation in near-critical-density(NCD)plasmas is studied by using multidimensional particle-in-cell(PIC)*** two-dimensional geometries,both P-and S-polarized laser pulses are used to drive these nonlinear structures and to check the polarization effects on *** the S-polarized case,the scattered waves can be captured by surrounding plasmas leading to the generation of post-solitons,while the main pulse excites convective electric currents leading to the formation of electron vortices through Kelvin-Helmholtz instability(KHI).In the P-polarized case,the scattered waves dissipate their energy by heating surrounding *** vortices are excited due to the hosing instability of the drive *** polarization dependent physical processes are reproduced in two different planes perpendicular to the laser propagation direction in three-dimensional simulation with linearly polarized laser *** current work provides inspiration for future experiments of laser-NCD plasma interactions.

关键词： stimulated Raman side scattering near-critical-density plasmas electron vortices post-solitons

Collimated GeV attosecond electron–positron bunches from a plasma channel driven by 10 PW lasers

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Matter and Radiation at Extremes 2019年第1期4卷 42-47页

作者： Xing-Long Zhu Min Chen Tong-Pu Yu Su-ming Weng Feng He zheng-ming sheng 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 Department of Physics National University of Defense TechnologyChangsha 410073China SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUK Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

High-energy positrons and bright g-ray sources are of great importance both in fundamental research and for practical ***,collimated GeV electron–positron pair jets and g-ray flashes are still rarely produced in the ***,we demonstrate that by irradiating a near-critical-density plasma channel with two 10 PW-scale laser pulses,highly directional GeV electron–positron pairs and bright g-ray beams can be efficiently ***-dimensional particle-incell simulations show the formation of GeV positron jets with high density(8×10^(21)=cm^(3)),attosecond duration(400 as),and a divergence angle of 14°.Additionally,ultrabright[2×10^(25) photons s^(-1)1 mm^(-2) mrad^(-2) (0.1%bandwidth_(-1)]collimated attosecond(370 as)g-ray flashes with a laser energy conversion efficiency of 5.6%are *** features show the significant advantage of using a plasma channel as compared with a uniformplasma and thus open up new possibilities for a wide variety of applications.

关键词： positron second directional

Electron Dynamics and Characteristics of Attosecond Electromagnetic Emissions in Relativistic Laser-Plasma Interactions

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Chinese Physics Letters 2018年第9期35卷 37-40页

作者： Yi-Ying Wu Quan-Li Dong Zhao-Hua Wang Ping Liu Cheng-Zhen Wang Yi-Hui Zhang zheng-ming sheng Jie Zhang School of Physics and Optoeleetronics Engineering Ludong UniversityYantai 264025 Beijing National Laboratory of Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190 School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240 Innovative Collaboration Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240 University of Chinese Academy of Sciences Beijing 100864

Generation of attosecond electromagnetic （EM） pulses and the associated electron dynamics are studied using particle-in-cell simulations of relativistic laser pulses interacting with over-dense plasma foil targets. The inter- action process is found to be so complicated even in the situation of utilizing driving laser pulses of only one cycle. Two electron bunches closely involved in the laser-driven wavebreaking process contribute to attosecond EM pulses through the coherent synchrotron emission process whose spectra are found to follow an exponential decay rule. Detailed investigations of electron dynamics indicate that the early part of the reflected EM emission is the high-harmonics produced through the relativistic oscillating mirror mechanism. High harmonics are also found to be generated through the Bremsstrahlung radiation by one electron bunch that participates in the wavebreaking process and decelerates when it experiences the local wavebreaking-generated high electrostatic field in the moving direction.

关键词： Electron Dynamics and Characteristics of Attosecond Electromagnetic Emissions in Relativistic Laser-Plasma Interactions