We propose a compact scheme to modulate a relativistic electron beam(REB)into three-dimensional(3D)nanoscale bunches by injecting a rarefied REB into an underdense plasma.This scheme self-consistently integrates the l...We propose a compact scheme to modulate a relativistic electron beam(REB)into three-dimensional(3D)nanoscale bunches by injecting a rarefied REB into an underdense plasma.This scheme self-consistently integrates the lateral focusing and axial modulation of the REB in its self-driven plasma wakefield.The REB first expels the plasma electrons in its path to form a wake,where the lateral force of the chargeseparation field compresses it to higher density,so that more plasma electrons are expelled as it propagates.The positive feedback loop is repeated until the REB becomes a thin electron filament of density a hundred times that of the original.As it continues to propagate in the elongated electron-free wake bubble,the axial electric field induces an energy chirp on the electron filament,and longitudinally modulates it into 3D nanoscale bunches by asynchronous envelope oscillations.The excitation conditions of this scheme with respect to the beam and plasma parameters,as well as the spatial scale of the obtained electron bunches,are analyzed analytically and agree well with particle-in-cell simulations.In addition,our radiation simulations show that coherent extreme ultraviolet radiation can be generated with such 3D nanoscale bunches.展开更多
The Ti-6Al-4V alloy is the most widely utilized titanium metal alloy globally,making the enhancement of its mechanical properties important.In this study,we achieved an ultimate tensile strength of 1.5 GPa through the...The Ti-6Al-4V alloy is the most widely utilized titanium metal alloy globally,making the enhancement of its mechanical properties important.In this study,we achieved an ultimate tensile strength of 1.5 GPa through the additive manufacturing(AM)of Ti-6Al-4V.Specifically,the Ti-6Al-4V alloy was fabricated via laser powder bed fusion(L-PBF)using Ti-6Al-4V powder subjected to cold plastic deformation(CPD Ti-6Al-4V).The microstructural evolution of the Ti-6Al-4V powder during CPD was analyzed in detail.The CPD Ti-6Al-4V powder exhibited a core-shell structure with subgrains and nanocrystals formed via high-density dislocations within the shell.In addition,the as-printed CPD Ti-6Al-4V alloy had an average grain size of approximately 1.9µm.The presence of interstitial elements and finer grains resulted in the formation of Ti-6Al-4V alloys with ultrahigh strengths(ultimate tensile strength of approximately 1500 MPa,yield strength of 1320 MPa,and elongation of 6%).This groundbreaking achievement paves the way for further advancements in AM technology and presents exciting opportunities for innovation across a range of high-strength materials,which are crucial for achieving optimal performance.展开更多
Slits have been widely used in laser-plasma interactions as plasma optical components for generating high-harmonic light and controlling laser-driven particle beams.Here,we propose and demonstrate that periodic thin s...Slits have been widely used in laser-plasma interactions as plasma optical components for generating high-harmonic light and controlling laser-driven particle beams.Here,we propose and demonstrate that periodic thin slits can be regarded as a new breed of optical elements for efficient focusing and guiding of intense laser pulse.The fundamental physics of intense laser interaction with thin slits is studied,and it is revealed that relativistic effects can lead to enhanced laser focusing far beyond the pure diffractive focusing regime.In addition,the interaction of an intense laser pulse with periodic thin slits makes it feasible to achieve multifold enhancement in both laser intensity and energy transfer efficiency compared with conventional waveguides.These results provide a novel method for manipulating ultra-intense laser pulses and should be of interest for many laser-based applications.展开更多
Branched flow is an interesting phenomenon that can occur in diverse systems.It is usually linear in the sense that the flow does not alter the properties of the medium.Branched flow of light on thin films has recentl...Branched flow is an interesting phenomenon that can occur in diverse systems.It is usually linear in the sense that the flow does not alter the properties of the medium.Branched flow of light on thin films has recently been discovered.It is therefore of interest to know whether nonlinear light branching can also occur.Here,using particle-in-cell simulations,we find that in the case of an intense laser propagating through a randomly uneven medium,cascading local photoionization by the incident laser,together with the response of freed electrons in the strong laser fields,triggers space–time-dependent optical unevenness.The resulting branching pattern depends dramatically on the laser intensity.That is,the branching here is distinct from the existing linear ones.The observed branching properties agree well with theoretical analyses based on the Helmholtz equation.Nonlinear branched propagation of intense lasers potentially opens up a new area for laser–matter interaction and may be relevant to other branching phenomena of a nonlinear nature.展开更多
This paper is concerned with the pattern dynamics of the generalized nonlinear Schrodinger equations(NSEs)relatedwith various nonlinear physical problems in plasmas.Our theoretical and numerical results show that the ...This paper is concerned with the pattern dynamics of the generalized nonlinear Schrodinger equations(NSEs)relatedwith various nonlinear physical problems in plasmas.Our theoretical and numerical results show that the higher-order nonlinear effects,acting as a Hamiltonian perturbation,break down the NSE integrability and lead to chaotic behaviors.Correspondingly,coherent structures are destroyed and replaced by complex patterns.Homoclinic orbit crossings in the phase space and stochastic partition of energy in Fourier modes show typical characteristics of the stochastic motion.Our investigations show that nonlinear phenomena,such as wave turbulence and laser filamentation,are associated with the homoclinic chaos.In particular,we found that the unstable manifolds W(u)possessing the hyperbolic fixed point correspond to an initial phase θ=45° and 225° ,and the stable manifolds W(s)correspond toθ=135° and 315° .展开更多
基金supported by the National Key R&D Program of China(Grant No.2024YFA1613400)the National Natural Science Foundation of China(Grant Nos.12475238,12175154,12205201,and 12475248)+5 种基金the Financial Support for Outstanding Talents Training Fund in Shenzhen(Project No.202101)the Shenzhen Science and Technology Program(Grant No.RCYX20221008092851073)the Guangdong Province Key Construction Discipline Scientific Research Capacity Improvement Project(Grant No.2021ZDJS107)the Natural Science Foundation of Guangdong(Grant No.2025A1515012853)the Natural Science Foundation of Top Talent of SZTU(Grant Nos.GDRC202310 and GDRC202423)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515010791).
文摘We propose a compact scheme to modulate a relativistic electron beam(REB)into three-dimensional(3D)nanoscale bunches by injecting a rarefied REB into an underdense plasma.This scheme self-consistently integrates the lateral focusing and axial modulation of the REB in its self-driven plasma wakefield.The REB first expels the plasma electrons in its path to form a wake,where the lateral force of the chargeseparation field compresses it to higher density,so that more plasma electrons are expelled as it propagates.The positive feedback loop is repeated until the REB becomes a thin electron filament of density a hundred times that of the original.As it continues to propagate in the elongated electron-free wake bubble,the axial electric field induces an energy chirp on the electron filament,and longitudinally modulates it into 3D nanoscale bunches by asynchronous envelope oscillations.The excitation conditions of this scheme with respect to the beam and plasma parameters,as well as the spatial scale of the obtained electron bunches,are analyzed analytically and agree well with particle-in-cell simulations.In addition,our radiation simulations show that coherent extreme ultraviolet radiation can be generated with such 3D nanoscale bunches.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(No.2020B1515120013)the National Natural Science Foundation of China(Nos.51971108 and 52271032)+1 种基金the Key Research and Development Program of Jiangsu Province(No.K22251901)the Shenzhen Science and Technology Innovation Commission(Nos.JCYJ20220818100612027 and JSGG20210420091802007).
文摘The Ti-6Al-4V alloy is the most widely utilized titanium metal alloy globally,making the enhancement of its mechanical properties important.In this study,we achieved an ultimate tensile strength of 1.5 GPa through the additive manufacturing(AM)of Ti-6Al-4V.Specifically,the Ti-6Al-4V alloy was fabricated via laser powder bed fusion(L-PBF)using Ti-6Al-4V powder subjected to cold plastic deformation(CPD Ti-6Al-4V).The microstructural evolution of the Ti-6Al-4V powder during CPD was analyzed in detail.The CPD Ti-6Al-4V powder exhibited a core-shell structure with subgrains and nanocrystals formed via high-density dislocations within the shell.In addition,the as-printed CPD Ti-6Al-4V alloy had an average grain size of approximately 1.9µm.The presence of interstitial elements and finer grains resulted in the formation of Ti-6Al-4V alloys with ultrahigh strengths(ultimate tensile strength of approximately 1500 MPa,yield strength of 1320 MPa,and elongation of 6%).This groundbreaking achievement paves the way for further advancements in AM technology and presents exciting opportunities for innovation across a range of high-strength materials,which are crucial for achieving optimal performance.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1603300)the National Natural Science Foundation of China(Grant Nos.12175154,12205201,12005149,and 11975214)+1 种基金the Shenzhen Science and Technology Program(Grant No.RCYX20221008092851073)used under UK EPSRC Contract Nos.EP/G055165/1 and EP/G056803/1.
文摘Slits have been widely used in laser-plasma interactions as plasma optical components for generating high-harmonic light and controlling laser-driven particle beams.Here,we propose and demonstrate that periodic thin slits can be regarded as a new breed of optical elements for efficient focusing and guiding of intense laser pulse.The fundamental physics of intense laser interaction with thin slits is studied,and it is revealed that relativistic effects can lead to enhanced laser focusing far beyond the pure diffractive focusing regime.In addition,the interaction of an intense laser pulse with periodic thin slits makes it feasible to achieve multifold enhancement in both laser intensity and energy transfer efficiency compared with conventional waveguides.These results provide a novel method for manipulating ultra-intense laser pulses and should be of interest for many laser-based applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.12205201,12175154,11875092,and 12005149)the Natural Science Foundation of Top Talent of SZTU(Grant Nos.2019010801001 and 2019020801001)+1 种基金GCS Jülich(Project No.QED20)in GermanyThe EPOCH code is used under a UK EPSRC contract(Grant Nos.EP/G055165/1 and EP/G056803/1).
文摘Branched flow is an interesting phenomenon that can occur in diverse systems.It is usually linear in the sense that the flow does not alter the properties of the medium.Branched flow of light on thin films has recently been discovered.It is therefore of interest to know whether nonlinear light branching can also occur.Here,using particle-in-cell simulations,we find that in the case of an intense laser propagating through a randomly uneven medium,cascading local photoionization by the incident laser,together with the response of freed electrons in the strong laser fields,triggers space–time-dependent optical unevenness.The resulting branching pattern depends dramatically on the laser intensity.That is,the branching here is distinct from the existing linear ones.The observed branching properties agree well with theoretical analyses based on the Helmholtz equation.Nonlinear branched propagation of intense lasers potentially opens up a new area for laser–matter interaction and may be relevant to other branching phenomena of a nonlinear nature.
基金This work is also supported by the National Natural Science Foundation of China grant Nos.10575013 and 10576007partially by the National Basic Research Program of China(973)(2007CB814802 and 2007CB815101).
文摘This paper is concerned with the pattern dynamics of the generalized nonlinear Schrodinger equations(NSEs)relatedwith various nonlinear physical problems in plasmas.Our theoretical and numerical results show that the higher-order nonlinear effects,acting as a Hamiltonian perturbation,break down the NSE integrability and lead to chaotic behaviors.Correspondingly,coherent structures are destroyed and replaced by complex patterns.Homoclinic orbit crossings in the phase space and stochastic partition of energy in Fourier modes show typical characteristics of the stochastic motion.Our investigations show that nonlinear phenomena,such as wave turbulence and laser filamentation,are associated with the homoclinic chaos.In particular,we found that the unstable manifolds W(u)possessing the hyperbolic fixed point correspond to an initial phase θ=45° and 225° ,and the stable manifolds W(s)correspond toθ=135° and 315° .
