Low-noise terahertz(THz)radiation over 100 MV/cm generation by a linearly-polarized relativistic laser pulse interacting with a near-critical-density(NCD)plasma slab is studied by theory and particle-in-cell(PIC)simul...Low-noise terahertz(THz)radiation over 100 MV/cm generation by a linearly-polarized relativistic laser pulse interacting with a near-critical-density(NCD)plasma slab is studied by theory and particle-in-cell(PIC)simulations.A theoretical model is established to examine the dipole-like radiation emission.The THz radiation is attributed to the singlecycle low-frequency surface current,which is longitudinally constrained by the quasi-equilibrium established by the laser ponderomotive force and the ponderomotively induced electrostatic force.Through theoretical analysis,the spatiotemporal characteristics,polarization property of the THz radiation,and the relation between the radiation strength with the initial parameters of driving laser and plasma are obtained,which are in good consistence with the PIC simulation results.Furthermore,it is found by PIC simulations that the generation of thermal electrons can be suppressed within the appropriate parameter regime,resulting in a clear THz radiation waveform.The appropriate parameter region is given for generating a low-noise intense THz radiation with peak strength reaching 100 MV/cm,which could find potential applications in nonlinear THz physics.展开更多
The effect of the polarizations of two counter-propagating relativistic laser pulses interacting with subwavelength thin solid-density foil is investigated.Three-dimensional particle-in-cell simulations and analytical...The effect of the polarizations of two counter-propagating relativistic laser pulses interacting with subwavelength thin solid-density foil is investigated.Three-dimensional particle-in-cell simulations and analytical modelling show that the interaction and resulting transverse instability depend strongly on the polarization directions as well as the intensity distribution of the resultant light field in the foil.The left-and right-handed circularly polarized laser pair with the same phase at the common focal spot in the ultrathin foil leads to the strongest distortion of the foil.The fastest growing mode and maximum growth rate depend mainly on the laser intensity.For all polarization and phase-difference combinations,the instability is weakest when the two laser pulses are exactly out of phase at the common focusing point in the foil.展开更多
The propagation of multiple ultraintense femtosecond lasers in underdense plasmas is investigated theoretically and numerically.We find that the energy merging effect between two in-phase seed lasers can be improved b...The propagation of multiple ultraintense femtosecond lasers in underdense plasmas is investigated theoretically and numerically.We find that the energy merging effect between two in-phase seed lasers can be improved by using two obliquely incident guiding lasers whose initial phase isπandπ/2 ahead of the seed laser.Particle-in-cell simulations show that due to the repulsion and energy transfer of the guiding laser,the peak intensity of the merged light is amplified by more than five times compared to the seed laser.The energy conversion efficiency from all incident lasers to the merged light is up to approximately 60%.The results are useful for many applications,including plasma-based optical amplification,charged particle acceleration and extremely intense magnetic field generation.展开更多
X/γ-rays have many potential applications in laboratory astrophysics and particle physics.Although several methods have been proposed for generating electron,positron,and X/γ-photon beams with angular momentum(AM),t...X/γ-rays have many potential applications in laboratory astrophysics and particle physics.Although several methods have been proposed for generating electron,positron,and X/γ-photon beams with angular momentum(AM),the generation of ultra-intense brilliant γ-rays is still challenging.Here,we present an all-optical scheme to generate a high-energy γ-photon beam with large beam angular momentum(BAM),small divergence,and high brilliance.In the first stage,a circularly polarized laser pulse with intensity of 10^(22) W/cm^(2) irradiates a micro-channel target,drags out electrons from the channel wall,and accelerates them to high energies via the longitudinal electric fields.During the process,the laser transfers its spin angular momentum(SAM)to the electrons’orbital angular momentum(OAM).In the second stage,the drive pulse is reflected by the attached fan-foil and a vortex laser pulse is thus formed.In the third stage,the energetic electrons collide head-on with the reflected vortex pulse and transfer their AM to the γ-photons via nonlinear Compton scattering.Three-dimensional particle-in-cell simulations show that the peak brilliance of the γ-ray beam is∼10^(22) photons·s^(-1)·mm^(-2)·mrad^(-2) per 0.1% bandwidth at 1 MeV with a peak instantaneous power of 25 TW and averaged BAM of 10^(6)h/photon.The AM conversion efficiency from laser to the γ-photons is unprecedentedly 0.67%.展开更多
A scheme for generating high-flux angularly uniform proton beams with high laser-to-proton energy conversion efficiency is proposed. Three laser beams are focused on a microwire array attached to a solid-density hemis...A scheme for generating high-flux angularly uniform proton beams with high laser-to-proton energy conversion efficiency is proposed. Three laser beams are focused on a microwire array attached to a solid-density hemispheric target. The laser-driven hot electrons from the front of the microwire hemisphere generate a hot-electron sheath in the hollow behind it, so that the protons on its back are accelerated by target normal sheath acceleration. The accelerated protons are of high flux, as well as angularly and energetically uniform. The scheme should be useful for applications involving warm dense matter, such as isochoric heating and modification of materials, as well as for proton therapy and inertial confinement fusion.展开更多
基金the National Natural Science Foundation of China(Grant Nos.11774430,12075157,11775202,and 12175310)the Scientific Research Foundation of Hunan Provincial Education Department(Grant No.20A042).
文摘Low-noise terahertz(THz)radiation over 100 MV/cm generation by a linearly-polarized relativistic laser pulse interacting with a near-critical-density(NCD)plasma slab is studied by theory and particle-in-cell(PIC)simulations.A theoretical model is established to examine the dipole-like radiation emission.The THz radiation is attributed to the singlecycle low-frequency surface current,which is longitudinally constrained by the quasi-equilibrium established by the laser ponderomotive force and the ponderomotively induced electrostatic force.Through theoretical analysis,the spatiotemporal characteristics,polarization property of the THz radiation,and the relation between the radiation strength with the initial parameters of driving laser and plasma are obtained,which are in good consistence with the PIC simulation results.Furthermore,it is found by PIC simulations that the generation of thermal electrons can be suppressed within the appropriate parameter regime,resulting in a clear THz radiation waveform.The appropriate parameter region is given for generating a low-noise intense THz radiation with peak strength reaching 100 MV/cm,which could find potential applications in nonlinear THz physics.
基金supported by the National Natural Science Foundation of China(Grant Nos.12175310,12275356,12305268,12105362,12375244,12135009 and U22411281)the Natural Science Foundation of Hunan Province(Grant Nos.2021JJ40653,2020JJ5031 and 2025JJ30002)+1 种基金the Scientific Research Foundation of the Hunan Provincial Education Department(Grant No.22B0655)the Hunan Provincial Innovation Foundation for Postgraduates(Grant No.CX20210006)。
文摘The effect of the polarizations of two counter-propagating relativistic laser pulses interacting with subwavelength thin solid-density foil is investigated.Three-dimensional particle-in-cell simulations and analytical modelling show that the interaction and resulting transverse instability depend strongly on the polarization directions as well as the intensity distribution of the resultant light field in the foil.The left-and right-handed circularly polarized laser pair with the same phase at the common focal spot in the ultrathin foil leads to the strongest distortion of the foil.The fastest growing mode and maximum growth rate depend mainly on the laser intensity.For all polarization and phase-difference combinations,the instability is weakest when the two laser pulses are exactly out of phase at the common focusing point in the foil.
基金supported by the National Natural Science Foundation of China(Grant Nos.12175310,12275356,12135009 and 12075157)the Natural Science Foundation of Hunan Province(Grant No.2022JJ20042)。
文摘The propagation of multiple ultraintense femtosecond lasers in underdense plasmas is investigated theoretically and numerically.We find that the energy merging effect between two in-phase seed lasers can be improved by using two obliquely incident guiding lasers whose initial phase isπandπ/2 ahead of the seed laser.Particle-in-cell simulations show that due to the repulsion and energy transfer of the guiding laser,the peak intensity of the merged light is amplified by more than five times compared to the seed laser.The energy conversion efficiency from all incident lasers to the merged light is up to approximately 60%.The results are useful for many applications,including plasma-based optical amplification,charged particle acceleration and extremely intense magnetic field generation.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0404802)National Natural Science Foundation of China(Grant Nos.11875319,11705280,11774430,and 11775144)the Science and Technology Innovation Program of Hunan Province(Grant No.2020RC4020)+2 种基金Research Project of NUDT(Grant Nos.ZK18-02-02 and ZK18-03-09)Fok Ying-Tong Education Foundation(Grant No.161007)financial support by Hunan Provincial Research and Innovation Foundation for Graduate Students of China(Grant Nos.CX20190017,CX20190018,CX20200002,and CX20200038)。
文摘X/γ-rays have many potential applications in laboratory astrophysics and particle physics.Although several methods have been proposed for generating electron,positron,and X/γ-photon beams with angular momentum(AM),the generation of ultra-intense brilliant γ-rays is still challenging.Here,we present an all-optical scheme to generate a high-energy γ-photon beam with large beam angular momentum(BAM),small divergence,and high brilliance.In the first stage,a circularly polarized laser pulse with intensity of 10^(22) W/cm^(2) irradiates a micro-channel target,drags out electrons from the channel wall,and accelerates them to high energies via the longitudinal electric fields.During the process,the laser transfers its spin angular momentum(SAM)to the electrons’orbital angular momentum(OAM).In the second stage,the drive pulse is reflected by the attached fan-foil and a vortex laser pulse is thus formed.In the third stage,the energetic electrons collide head-on with the reflected vortex pulse and transfer their AM to the γ-photons via nonlinear Compton scattering.Three-dimensional particle-in-cell simulations show that the peak brilliance of the γ-ray beam is∼10^(22) photons·s^(-1)·mm^(-2)·mrad^(-2) per 0.1% bandwidth at 1 MeV with a peak instantaneous power of 25 TW and averaged BAM of 10^(6)h/photon.The AM conversion efficiency from laser to the γ-photons is unprecedentedly 0.67%.
基金supported by the National Natural Science Foundation of China(Nos.12105362,12175310,12275356and 12305268)the Natural Science Foundation of Hunan Province(Nos.2022JJ20042,2021JJ40653 and2020JJ5031)+1 种基金the Scientific Research Foundation of Hunan Provincial Education Department(No.22B0655)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20210006)
文摘A scheme for generating high-flux angularly uniform proton beams with high laser-to-proton energy conversion efficiency is proposed. Three laser beams are focused on a microwire array attached to a solid-density hemispheric target. The laser-driven hot electrons from the front of the microwire hemisphere generate a hot-electron sheath in the hollow behind it, so that the protons on its back are accelerated by target normal sheath acceleration. The accelerated protons are of high flux, as well as angularly and energetically uniform. The scheme should be useful for applications involving warm dense matter, such as isochoric heating and modification of materials, as well as for proton therapy and inertial confinement fusion.
