It was found that the free Fe in the melted zone of the as—cast Nd_2Fe_(14)B alloy could be dissolved by Iaser/electron beam.The growth direction of Nd_2Fe_(14)B grains is nearly perpendicular to the sur- face of the...It was found that the free Fe in the melted zone of the as—cast Nd_2Fe_(14)B alloy could be dissolved by Iaser/electron beam.The growth direction of Nd_2Fe_(14)B grains is nearly perpendicular to the sur- face of the samples.EDX examination showed that Fe element was homogeneously distributed in the melted zone.Results presented in this paper have giv- en hint to remove free Fe in as—cast Nd_2Fe_(14)B alloy.展开更多
The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of...The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.展开更多
Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-de...Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.展开更多
Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung H...Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer substrates.The laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μm.Moreover,they maintain impedance and charge-storage capacity even after 1 h of sonication.The micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.展开更多
The rapid advancements of ultrafast intense laser technology have opened new avenues for investigating entanglement in laser-induced systems. However, the application of these advances in quantum technology requires a...The rapid advancements of ultrafast intense laser technology have opened new avenues for investigating entanglement in laser-induced systems. However, the application of these advances in quantum technology requires a reliable and universally applicable method for enhancing and regulating entanglement. Here we demonstrate how a few-cycle intense laser field can significantly enhance the degree of entanglement compared to its multi-cycle counterpart, using the example of electron–electron entanglement of orbital angular momentum(OAM) states in recollision-excitation non-sequential double ionization of Ar atoms. By confining the ionization dynamics to a specific narrow time window, the few-cycle pulse purifies the electron trajectories, thereby ensuring high coherence between entangled OAM channels and enhancing entanglement. Furthermore, the degree of entanglement can be efficiently modulated by varying the carrier envelope phase of the few-cycle laser pulse, which is achieved by altering the population across OAM channels. Optimizing coherence through electron trajectory purification with a designed specific temporal waveform of laser field provides a general pathway for enhancing entanglement in laser-induced systems.展开更多
A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation...A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation source requires relatively ultrashort electron bunches to produce intense coherent THz pulses.Three electron bunch compression processes are utilized in the PCELL accelerator system comprising pre-bunch compression in an alpha magnet,velocity bunching in a radio-frequency(RF)linear accelerator(linac),and magnetic bunch compression in a 180°acromat system.Electron bunch compression in the magnetic compressor system poses considerable challenges,which are addressed through the use of three quadrupole doublets.The strengths of the quadrupole fields significantly influence the rotation of the beam line longitudinal phase space distribution along the bunch compressor.Start-to-end beam dynamics simulations using the ASTRA code were performed to optimize the electron beam properties for generating super-radiant THz-FEL radiation.The operational parameters considered in the simulations comprise the alpha magnet gradient,linac RF phase,and quadrupole field strengths.The optimization results show that 10-16MeV femtosecond electron bunches with a low energy spread(~0.2%),small normalized emittance(~15πmm·mrad),and high peak current(165-247A)can be produced by the PCELL accelerator system at the optimal parameters.A THz-FEL with sub-microjoule pulse energies can thus be obtained at the optimized electron beam parameters.The physical and conceptual design of the THz-FEL beamline were completed based on the beam dynamics simulation results.The construction and installation of this beamline are currently underway and expected to be completed by mid-2024.The commissioning of the beamline will then commence.展开更多
Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challe...Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challenges.In this work,we demonstrate for the firs time that the coherent radiation farfiel patterns from laser–foil interactions can serve as an in situ,real-time,and easy-to-implement diagnostic for an ultraintense laser focus.The laser-driven electron sheets,curved by the spatially varying laser fiel and leaving the targets at nearly the speed of light,produce doughnut-shaped patterns depending on the shapes of the focal spot and the absolute laser intensities.Assisted by particle-in-cell simulations,we can achieve measurements of the intensity and the focal spot,and provide immediate feedback to optimize the focal spots for extremely high intensity.展开更多
This research examines the dynamics of a cosh-Gaussian laser pulse travelling through a vacuum and its impact on electron acceleration. We examine the impact of several critical factors, such as laser electric field a...This research examines the dynamics of a cosh-Gaussian laser pulse travelling through a vacuum and its impact on electron acceleration. We examine the impact of several critical factors, such as laser electric field amplitude, decentered parameter, beam waist, and laser chirp parameter, on the energy gain of electrons using coupled momentum equations. Our results indicate that the energy acquisition of electrons escalates with the amplitude of the laser electric field, decentered parameter, and chirp parameter. An appropriate beam waist is essential for attaining energyefficient electron acceleration in a vacuum. Through the optimization of these parameters, we get a maximum electron energy gain of 2.80 Ge V. This study highlights the significance of customized laser pulse attributes in improving electron acceleration and aids in the progression of high-energy particle physics.展开更多
The high temporal and spatial coherence of free electron lasers(FELs)reduces the uniformity of the illumination field,leading to scattering effects that blur the edges of patterns,resulting in diminished accuracy and ...The high temporal and spatial coherence of free electron lasers(FELs)reduces the uniformity of the illumination field,leading to scattering effects that blur the edges of patterns,resulting in diminished accuracy and clarity.Traditional imaging models regard the light source as fully incoherent,making it difficult to assess the impact of partially coherent light fields on imaging.If FELs are used in imaging systems,their coherence must be considered.To address this issue,this study explores the relationship between coherence,imaging quality and speckle contrast through a simulation method based on random phases.The method divides the light beam into temporal and spatial coherence cells,analyzes their interactions,and simulates imaging results under different coherence conditions.Additionally,speckle patterns for various illumination modes are calculated to evaluate their effects on speckle contrast and illumination uniformity.The results indicate that under different illumination modes,illumination uniformity decreases as coherence increases,while speckle contrast increases with higher coherence.In terms of imaging quality,higher coherence leads to an increase in both line edge roughness(LER)and line width roughness(LWR),thereby reducing the imaging quality.Additionally,the narrower the line width,the greater the impact of coherence on the imaging quality,resulting in poorer imaging performance.展开更多
A thermionic gun is endowed with a long bunch tail,which presents challenges for the compact terahertz free electron laser(FEL)facility at the Huazhong University of Science and Technology.Owing to a large energy spre...A thermionic gun is endowed with a long bunch tail,which presents challenges for the compact terahertz free electron laser(FEL)facility at the Huazhong University of Science and Technology.Owing to a large energy spread,the tail particles do not contribute to the radiation.In the original design,an x-direction slit is used in the dispersive section of the transport line to remove the tail particles.This paper presents an improved scheme to remove the tail by introducing an RF beam chopper system at the exit of the electron gun,to prevent a significant number of tail particles from entering the linac.The facility remains compact while effectively removing the tail of the bunch.The parameters of the beam chopper system are designed.Bunch parameters and radiation performance are analyzed via a start-to-end simulation.The findings indicate that 43%of the particles can pass through the beam chopper system for subsequent acceleration and transport,which saves the RF power,reduces beam loss in the linac,reduces background noise,and suppresses the sideband instability.Simultaneously,the beam chopper system causes an increase in beam emittance,energy spread,and an offset in the center of the bunch.These effects can be mitigated by a solenoid,linac,and steering coils.The simulation results for the FEL show that the micro-pulse energy is greater than 1.1μJ in the frequency range of 2.8-9.7 THz,and the maximum micro-pulse energy is 1.28μJ.展开更多
High-density interconnect(HDI)soft electronics that can integrate multiple individual functions into one miniaturized monolithic system is promising for applications related to smart healthcare,soft robotics,and human...High-density interconnect(HDI)soft electronics that can integrate multiple individual functions into one miniaturized monolithic system is promising for applications related to smart healthcare,soft robotics,and human-machine interactions.However,despite the recent advances,the development of three-dimensional(3D)soft electronics with both high resolution and high integration is still challenging because of the lack of efficient manufacturing methods to guarantee interlayer alignment of the high-density vias and reliable interlayer electrical conductivity.Here,an advanced 3D laser printing pathway,based on femtosecond laser direct writing(FLDW),is demonstrated for preparing liquid metal(LM)-based any layer HDI soft electronics.FLDW technology,with the characteristics of high spatial resolution and high precision,allows the maskless fabrication of high-resolution embedded LM microchannels and high-density vertical interconnect accesses for 3D integrated circuits.High-aspect-ratio blind/through LM microstructures are formed inside the elastomer due to the supermetalphobicity induced during laser ablation.The LM-based HDI circuit featuring high resolution(~1.5μm)and high integration(10-layer electrical interconnection)is achieved for customized soft electronics,including various customized multilayer passive electric components,soft multilayer circuit,and cross-scale multimode sensors.The 3D laser printing method provides a versatile approach for developing chip-level soft electronics.展开更多
X-ray free-electron lasers(XFELs)can generate bright X-ray pulses with short durations and narrow bandwidths,leading to extensive applica-tions in many disciplines such as biology,materials science,and ultrafast scien...X-ray free-electron lasers(XFELs)can generate bright X-ray pulses with short durations and narrow bandwidths,leading to extensive applica-tions in many disciplines such as biology,materials science,and ultrafast science.Recently,there has been a growing demand for X-ray pulses with high photon energy,especially from developments in“diffraction-before-destruction”applications and in dynamic mesoscale materials science.Here,we propose utilizing the electron beams at XFELs to drive a meter-scale two-bunch plasma wakefield accelerator and double the energy of the accelerated beam in a compact and inexpensive way.Particle-in-cell simulations are performed to study the beam quality degradation under different beam loading scenarios and nonideal issues,and the results show that more than half of the accelerated beam can meet the requirements of XFELs.After its transport to the undulator,the accelerated beam can improve the photon energy to 22 keV by a factor of around four while maintaining the peak power,thus offering a promising pathway toward high-photon-energy XFELs.展开更多
We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using K...We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using Ka time-resolved imaging,it is found that in the case of massive targets,the hot-electron generation follows the laser pulse intensity with a short delay needed for favorable plasma formation.Conversely,a significant delay in the x-ray emission compared with the laser pulse intensity profile is observed in the case of thin targets.Theoretical analysis and numerical simulations suggest that this is related to radiation preheating of the foil and the increase in hot-electron lifetime in a hot expanding plasma.展开更多
We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple elect...We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.展开更多
Streamer discharges that do not transition to a spark channel are now being widely investigated.One of these discharges is the apokamp discharge,in which streamers start from a diffuse spark channel having a curved sh...Streamer discharges that do not transition to a spark channel are now being widely investigated.One of these discharges is the apokamp discharge,in which streamers start from a diffuse spark channel having a curved shape at a high repetition rate of voltage pulse.In this work,to estimate the electron concentration in the plasma forming the apokamp a digital holographic laser scanning method is applied for the first time.The method is based on a comparison of the phases of two optical wavefronts,registered at different time instants in the form of digital holograms.The result of the phase comparison between the wavefronts is presented in the form of a numerically calculated map of the phase difference of the reconstructed wavefronts.A gas-discharge plasma is a phase(transparent)object,and the interference fringes are formed as a result of the change in the refractive index introduced by the plasma with respect to the original unperturbed medium.The obtained value of the refractive index allows estimation of the concentration of electrons in the spark channel plasma.It is shown that at as the voltage pulse repetition rate increases from 5 to 50 kHz the concentration of electrons in the plasma forming the apokamp decreases by an estimated four times.展开更多
Metallic nanowires have served as novel materials for soft electronics due to their outstanding mechanical compliance and electrical properties.However,weak adhesion and low mechanical robustness of nanowire networks ...Metallic nanowires have served as novel materials for soft electronics due to their outstanding mechanical compliance and electrical properties.However,weak adhesion and low mechanical robustness of nanowire networks to substrates significantly undermine their reliability,necessitating the use of an insulating protective layer,which greatly limits their utility.Herein,we present a versatile and generalized laser-based process that simultaneously achieves strong adhesion and mechanical robustness of nanowire networks on diverse substrates without the need for a protective layer.In this method,the laser-induced photothermal energy at the interface between the nanowire network and the substrate facilitates the interpenetration of the nanowire network and the polymer matrix,resulting in mechanical interlocking through percolation.This mechanism is broadly applicable across different metallic nanowires and thermoplastic substrates,significantly enhancing its universality in diverse applications.Thereby,we demonstrated the mechanical robustness of nanowires in reusable wearable physiological sensors on the skin without compromising the performance of the sensor.Furthermore,enhanced robustness and electrical conductivity by the laser-induced interlocking enables a stable functionalization of conducting polymers in a wet environment,broadening its application into various electrochemical devices.展开更多
A theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave(SCW) in the amplification section of a superheterodyne free electron laser(FEL) was carrie...A theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave(SCW) in the amplification section of a superheterodyne free electron laser(FEL) was carried out. One of the ways to significantly increase the saturation level of the slow SCW is maintaining the conditions of a three-wave parametric resonance between the slow, fast SCWs and the resulting pump electric field. This can be done by introducing the quasielectrostatic support in the superheterodyne FEL amplification section. Also, it was found that the generated pump electric field significantly influences the maintenance of parametric resonance conditions. As a result, this increases the saturation level of the slow SCW by 70%. Finally, the quasi-electrostatic support significantly reduces the maximum value of the electrostatic undulator pump field strength, which is necessary to achieve the maximum saturation level of the slow SCW.展开更多
Lead-halide perovskite nanoparticles(LHP NPs) are highly promising materials for next-generation displays and solid-state lighting due to their exceptional optical properties. However, their inherent instability prese...Lead-halide perovskite nanoparticles(LHP NPs) are highly promising materials for next-generation displays and solid-state lighting due to their exceptional optical properties. However, their inherent instability presents a significant challenge. Recent advances have demonstrated that optoelectronic devices based on monolayer nanoparticle films exhibit both high luminescence efficiency and long-term stability.Our research demonstrates that mobility limitations and anisotropic alignments in CsPbBr3nanocube monolayer films are key to their stabilization, hindering spontaneous growth through face-to-face fusion and resulting in the formation of connecting necks in a diagonal direction. Introducing laser irradiation confirmed this by significantly accelerating nanocubes growth, increasing mobility, and enhancing local structural ordering, leading to larger and more regularly shaped nanosheets. Fourier transform infrared spectroscopy and energy dispersive spectroscopy line-scan analyses indicated that laser irradiation did not disrupt the ligand structure. Transmission electron microscopy and correlative cathodoluminescence electron microscopy revealed the effects of post-growth and heterogeneous structures, including enhanced luminescence and inhomogeneous intensity in the nanosheets. These findings deepen the understanding of the post-growth mechanism of monolayer nanoparticles and the structure-emission correlation and highlight the unique role of laser irradiation in directing the formation of well-defined and regular nanostructures.展开更多
The doping evolution of the nodal electron dynamics in the trilayer cuprate superconductor Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ)(Bi2223)is investigated using high-resolution laser-based angle-resolved photoemission spectr...The doping evolution of the nodal electron dynamics in the trilayer cuprate superconductor Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ)(Bi2223)is investigated using high-resolution laser-based angle-resolved photoemission spectroscopy(ARPES).Bi2223single crystals with different doping levels are prepared by controlled annealing,which cover the underdoped,optimallydoped and overdoped regions.The electronic phase diagram of Bi2223 is established which describes the Tcdependence on the sample doping level.The doping dependence of the nodal Fermi momentum for the outer(OP)and inner(IP)CuO_(2)planes is determined.Charge distribution imbalance between the OP and IP CuO_(2)planes is quantified,showing enhanced disparity with increasing doping.Nodal band dispersions demonstrate a prominent kink at~94 meV in the IP band,attributed to the unique Cu coordination in the IP plane,while a weaker~60 meV kink is observed in the OP band.The nodal Fermi velocity of both OP and IP bands is nearly constant at~1.62 eV·A independent of doping.These results provide important information to understand the origin of high Tcand superconductivity mechanism in high temperature cuprate superconductors.展开更多
文摘It was found that the free Fe in the melted zone of the as—cast Nd_2Fe_(14)B alloy could be dissolved by Iaser/electron beam.The growth direction of Nd_2Fe_(14)B grains is nearly perpendicular to the sur- face of the samples.EDX examination showed that Fe element was homogeneously distributed in the melted zone.Results presented in this paper have giv- en hint to remove free Fe in as—cast Nd_2Fe_(14)B alloy.
基金supported by the National Natural Science Foundation of China(Grant Nos.11804348,11775056,11975154,12225505,and 12405281)the Science Challenge(Project No.TZ2018005)+2 种基金supported by the Shanghai Pujiang Program(Grant No.23PJ1414600)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0890203)supported by the Accelerator Technology Helmholtz Infrastructure consortium ATHENA.
文摘The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.
基金funding from Grant No. HIDSS-0002 DASHH (Data Science in Hamburg-Helmholtz Graduate School for the Structure of Matter)partially supported by the Helmholtz Imaging platform through the project “Smart Phase.”
文摘Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.
基金supported by the National Natural Science Foundation of China(52475610)Zhejiang Provincial Natural Science Foundation of China(LDQ24E050001).
文摘Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer substrates.The laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μm.Moreover,they maintain impedance and charge-storage capacity even after 1 h of sonication.The micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.
基金supported by the National Natural Science Foundation of China (Grant Nos.12274273and 12450402)the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302101)。
文摘The rapid advancements of ultrafast intense laser technology have opened new avenues for investigating entanglement in laser-induced systems. However, the application of these advances in quantum technology requires a reliable and universally applicable method for enhancing and regulating entanglement. Here we demonstrate how a few-cycle intense laser field can significantly enhance the degree of entanglement compared to its multi-cycle counterpart, using the example of electron–electron entanglement of orbital angular momentum(OAM) states in recollision-excitation non-sequential double ionization of Ar atoms. By confining the ionization dynamics to a specific narrow time window, the few-cycle pulse purifies the electron trajectories, thereby ensuring high coherence between entangled OAM channels and enhancing entanglement. Furthermore, the degree of entanglement can be efficiently modulated by varying the carrier envelope phase of the few-cycle laser pulse, which is achieved by altering the population across OAM channels. Optimizing coherence through electron trajectory purification with a designed specific temporal waveform of laser field provides a general pathway for enhancing entanglement in laser-induced systems.
基金support from the NSRF via the Program Management Unit for Human Resources&Institutional Development,Research,and Innovation(No.B05F650022),as well as from Chiang Mai University.
文摘A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation source requires relatively ultrashort electron bunches to produce intense coherent THz pulses.Three electron bunch compression processes are utilized in the PCELL accelerator system comprising pre-bunch compression in an alpha magnet,velocity bunching in a radio-frequency(RF)linear accelerator(linac),and magnetic bunch compression in a 180°acromat system.Electron bunch compression in the magnetic compressor system poses considerable challenges,which are addressed through the use of three quadrupole doublets.The strengths of the quadrupole fields significantly influence the rotation of the beam line longitudinal phase space distribution along the bunch compressor.Start-to-end beam dynamics simulations using the ASTRA code were performed to optimize the electron beam properties for generating super-radiant THz-FEL radiation.The operational parameters considered in the simulations comprise the alpha magnet gradient,linac RF phase,and quadrupole field strengths.The optimization results show that 10-16MeV femtosecond electron bunches with a low energy spread(~0.2%),small normalized emittance(~15πmm·mrad),and high peak current(165-247A)can be produced by the PCELL accelerator system at the optimal parameters.A THz-FEL with sub-microjoule pulse energies can thus be obtained at the optimized electron beam parameters.The physical and conceptual design of the THz-FEL beamline were completed based on the beam dynamics simulation results.The construction and installation of this beamline are currently underway and expected to be completed by mid-2024.The commissioning of the beamline will then commence.
基金supported by the Guangdong High Level Innovation Research Institute(Grant No.2021B0909050006)the National Grand Instrument Project(Grant No.2019YFF01014402)+1 种基金the National Natural Science Foundation of China(Grant No.12205008)support from the National Science Fund for Distinguished Young Scholars(Grant No.12225501)。
文摘Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challenges.In this work,we demonstrate for the firs time that the coherent radiation farfiel patterns from laser–foil interactions can serve as an in situ,real-time,and easy-to-implement diagnostic for an ultraintense laser focus.The laser-driven electron sheets,curved by the spatially varying laser fiel and leaving the targets at nearly the speed of light,produce doughnut-shaped patterns depending on the shapes of the focal spot and the absolute laser intensities.Assisted by particle-in-cell simulations,we can achieve measurements of the intensity and the focal spot,and provide immediate feedback to optimize the focal spots for extremely high intensity.
文摘This research examines the dynamics of a cosh-Gaussian laser pulse travelling through a vacuum and its impact on electron acceleration. We examine the impact of several critical factors, such as laser electric field amplitude, decentered parameter, beam waist, and laser chirp parameter, on the energy gain of electrons using coupled momentum equations. Our results indicate that the energy acquisition of electrons escalates with the amplitude of the laser electric field, decentered parameter, and chirp parameter. An appropriate beam waist is essential for attaining energyefficient electron acceleration in a vacuum. Through the optimization of these parameters, we get a maximum electron energy gain of 2.80 Ge V. This study highlights the significance of customized laser pulse attributes in improving electron acceleration and aids in the progression of high-energy particle physics.
文摘The high temporal and spatial coherence of free electron lasers(FELs)reduces the uniformity of the illumination field,leading to scattering effects that blur the edges of patterns,resulting in diminished accuracy and clarity.Traditional imaging models regard the light source as fully incoherent,making it difficult to assess the impact of partially coherent light fields on imaging.If FELs are used in imaging systems,their coherence must be considered.To address this issue,this study explores the relationship between coherence,imaging quality and speckle contrast through a simulation method based on random phases.The method divides the light beam into temporal and spatial coherence cells,analyzes their interactions,and simulates imaging results under different coherence conditions.Additionally,speckle patterns for various illumination modes are calculated to evaluate their effects on speckle contrast and illumination uniformity.The results indicate that under different illumination modes,illumination uniformity decreases as coherence increases,while speckle contrast increases with higher coherence.In terms of imaging quality,higher coherence leads to an increase in both line edge roughness(LER)and line width roughness(LWR),thereby reducing the imaging quality.Additionally,the narrower the line width,the greater the impact of coherence on the imaging quality,resulting in poorer imaging performance.
基金supported by the National Natural Science Foundation of China(No.12175077).
文摘A thermionic gun is endowed with a long bunch tail,which presents challenges for the compact terahertz free electron laser(FEL)facility at the Huazhong University of Science and Technology.Owing to a large energy spread,the tail particles do not contribute to the radiation.In the original design,an x-direction slit is used in the dispersive section of the transport line to remove the tail particles.This paper presents an improved scheme to remove the tail by introducing an RF beam chopper system at the exit of the electron gun,to prevent a significant number of tail particles from entering the linac.The facility remains compact while effectively removing the tail of the bunch.The parameters of the beam chopper system are designed.Bunch parameters and radiation performance are analyzed via a start-to-end simulation.The findings indicate that 43%of the particles can pass through the beam chopper system for subsequent acceleration and transport,which saves the RF power,reduces beam loss in the linac,reduces background noise,and suppresses the sideband instability.Simultaneously,the beam chopper system causes an increase in beam emittance,energy spread,and an offset in the center of the bunch.These effects can be mitigated by a solenoid,linac,and steering coils.The simulation results for the FEL show that the micro-pulse energy is greater than 1.1μJ in the frequency range of 2.8-9.7 THz,and the maximum micro-pulse energy is 1.28μJ.
基金supported by the National Science Foundation of China under the Grant Nos.12127806 and 62175195the International Joint Research Laboratory for Micro/Nano Manufacturing and Measurement Technologies。
文摘High-density interconnect(HDI)soft electronics that can integrate multiple individual functions into one miniaturized monolithic system is promising for applications related to smart healthcare,soft robotics,and human-machine interactions.However,despite the recent advances,the development of three-dimensional(3D)soft electronics with both high resolution and high integration is still challenging because of the lack of efficient manufacturing methods to guarantee interlayer alignment of the high-density vias and reliable interlayer electrical conductivity.Here,an advanced 3D laser printing pathway,based on femtosecond laser direct writing(FLDW),is demonstrated for preparing liquid metal(LM)-based any layer HDI soft electronics.FLDW technology,with the characteristics of high spatial resolution and high precision,allows the maskless fabrication of high-resolution embedded LM microchannels and high-density vertical interconnect accesses for 3D integrated circuits.High-aspect-ratio blind/through LM microstructures are formed inside the elastomer due to the supermetalphobicity induced during laser ablation.The LM-based HDI circuit featuring high resolution(~1.5μm)and high integration(10-layer electrical interconnection)is achieved for customized soft electronics,including various customized multilayer passive electric components,soft multilayer circuit,and cross-scale multimode sensors.The 3D laser printing method provides a versatile approach for developing chip-level soft electronics.
基金supported by the National Grand Instrument Project No. SQ2019YFF01014400the Natural Science Foundation of China (Grant Nos. 12375147, 12435011, 12075030)+2 种基金the Beijing Outstanding Young Scientist Project, Project for Young Scientists in Basic Research of Chinese Academy of Sciences (YSBR-115)the Beijing Normal University Scientific Research Initiation Fund for Introducing Talents No. 310432104the Fundamental Research Funds for the Central Universities, Peking University
文摘X-ray free-electron lasers(XFELs)can generate bright X-ray pulses with short durations and narrow bandwidths,leading to extensive applica-tions in many disciplines such as biology,materials science,and ultrafast science.Recently,there has been a growing demand for X-ray pulses with high photon energy,especially from developments in“diffraction-before-destruction”applications and in dynamic mesoscale materials science.Here,we propose utilizing the electron beams at XFELs to drive a meter-scale two-bunch plasma wakefield accelerator and double the energy of the accelerated beam in a compact and inexpensive way.Particle-in-cell simulations are performed to study the beam quality degradation under different beam loading scenarios and nonideal issues,and the results show that more than half of the accelerated beam can meet the requirements of XFELs.After its transport to the undulator,the accelerated beam can improve the photon energy to 22 keV by a factor of around four while maintaining the peak power,thus offering a promising pathway toward high-photon-energy XFELs.
基金funding via EUROfusion Enabling research Project No.AWP21-ENR-01-CEA-02“Advancing Shock Ignition for Direct-Drive Inertial Fusion,”the framework of the EUROfusion Consortium,funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No.101052200-EUROfusion)+2 种基金the Czech Ministry of Education,Youth and Sports (CMEYS) for funding the operation of the PALS facility (Grant No.LM2023068)the EuroHPC Joint Undertaking for awarding access to Karolina at IT4Innovations (VSB-TU),Czechia under Project No.EHPC-REG-2023R02-006(DD-23-157)the Ministry of Education,Youth and Sports of the Czech Republic through e-INFRA CZ (Grant No.ID:90140)
文摘We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using Ka time-resolved imaging,it is found that in the case of massive targets,the hot-electron generation follows the laser pulse intensity with a short delay needed for favorable plasma formation.Conversely,a significant delay in the x-ray emission compared with the laser pulse intensity profile is observed in the case of thin targets.Theoretical analysis and numerical simulations suggest that this is related to radiation preheating of the foil and the increase in hot-electron lifetime in a hot expanding plasma.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602502)the National Natural Science Foundation of China(Grant No.12450404)。
文摘We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.
基金performed in accordance with the support of the Russian Science Foundation(RSF)(No.23-79-00023)。
文摘Streamer discharges that do not transition to a spark channel are now being widely investigated.One of these discharges is the apokamp discharge,in which streamers start from a diffuse spark channel having a curved shape at a high repetition rate of voltage pulse.In this work,to estimate the electron concentration in the plasma forming the apokamp a digital holographic laser scanning method is applied for the first time.The method is based on a comparison of the phases of two optical wavefronts,registered at different time instants in the form of digital holograms.The result of the phase comparison between the wavefronts is presented in the form of a numerically calculated map of the phase difference of the reconstructed wavefronts.A gas-discharge plasma is a phase(transparent)object,and the interference fringes are formed as a result of the change in the refractive index introduced by the plasma with respect to the original unperturbed medium.The obtained value of the refractive index allows estimation of the concentration of electrons in the spark channel plasma.It is shown that at as the voltage pulse repetition rate increases from 5 to 50 kHz the concentration of electrons in the plasma forming the apokamp decreases by an estimated four times.
基金supported by the National Research Foundation of Korea(NRF)Grant(RS-2024-00343512,RS-2024-00416938).
文摘Metallic nanowires have served as novel materials for soft electronics due to their outstanding mechanical compliance and electrical properties.However,weak adhesion and low mechanical robustness of nanowire networks to substrates significantly undermine their reliability,necessitating the use of an insulating protective layer,which greatly limits their utility.Herein,we present a versatile and generalized laser-based process that simultaneously achieves strong adhesion and mechanical robustness of nanowire networks on diverse substrates without the need for a protective layer.In this method,the laser-induced photothermal energy at the interface between the nanowire network and the substrate facilitates the interpenetration of the nanowire network and the polymer matrix,resulting in mechanical interlocking through percolation.This mechanism is broadly applicable across different metallic nanowires and thermoplastic substrates,significantly enhancing its universality in diverse applications.Thereby,we demonstrated the mechanical robustness of nanowires in reusable wearable physiological sensors on the skin without compromising the performance of the sensor.Furthermore,enhanced robustness and electrical conductivity by the laser-induced interlocking enables a stable functionalization of conducting polymers in a wet environment,broadening its application into various electrochemical devices.
文摘A theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave(SCW) in the amplification section of a superheterodyne free electron laser(FEL) was carried out. One of the ways to significantly increase the saturation level of the slow SCW is maintaining the conditions of a three-wave parametric resonance between the slow, fast SCWs and the resulting pump electric field. This can be done by introducing the quasielectrostatic support in the superheterodyne FEL amplification section. Also, it was found that the generated pump electric field significantly influences the maintenance of parametric resonance conditions. As a result, this increases the saturation level of the slow SCW by 70%. Finally, the quasi-electrostatic support significantly reduces the maximum value of the electrostatic undulator pump field strength, which is necessary to achieve the maximum saturation level of the slow SCW.
基金National Key Research and Development Program of China(2023YFA1507602)National Natural Science Foundation of China (22171010, 62174011)。
文摘Lead-halide perovskite nanoparticles(LHP NPs) are highly promising materials for next-generation displays and solid-state lighting due to their exceptional optical properties. However, their inherent instability presents a significant challenge. Recent advances have demonstrated that optoelectronic devices based on monolayer nanoparticle films exhibit both high luminescence efficiency and long-term stability.Our research demonstrates that mobility limitations and anisotropic alignments in CsPbBr3nanocube monolayer films are key to their stabilization, hindering spontaneous growth through face-to-face fusion and resulting in the formation of connecting necks in a diagonal direction. Introducing laser irradiation confirmed this by significantly accelerating nanocubes growth, increasing mobility, and enhancing local structural ordering, leading to larger and more regularly shaped nanosheets. Fourier transform infrared spectroscopy and energy dispersive spectroscopy line-scan analyses indicated that laser irradiation did not disrupt the ligand structure. Transmission electron microscopy and correlative cathodoluminescence electron microscopy revealed the effects of post-growth and heterogeneous structures, including enhanced luminescence and inhomogeneous intensity in the nanosheets. These findings deepen the understanding of the post-growth mechanism of monolayer nanoparticles and the structure-emission correlation and highlight the unique role of laser irradiation in directing the formation of well-defined and regular nanostructures.
基金supported by the National Natural Science Foundation of China(Grant Nos.12488201 by X.J.Z.,12374066 by L.Z.,and 12374154 by X.T.L.)the National Key Research and Development Program of China(Grant Nos.2021YFA1401800 by X.J.Z.,2022YFA1604200 by L.Z.,2022YFA1403900 by G.D.L.and 2023YFA1406000by X.T.L.)+3 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000by X.J.Z.)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301800 by X.J.Z.)the Youth Innovation Promotion Association of CAS(Grant No.Y2021006 by L.Z.)the Synergetic Extreme Condition User Facility(SECUF)。
文摘The doping evolution of the nodal electron dynamics in the trilayer cuprate superconductor Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ)(Bi2223)is investigated using high-resolution laser-based angle-resolved photoemission spectroscopy(ARPES).Bi2223single crystals with different doping levels are prepared by controlled annealing,which cover the underdoped,optimallydoped and overdoped regions.The electronic phase diagram of Bi2223 is established which describes the Tcdependence on the sample doping level.The doping dependence of the nodal Fermi momentum for the outer(OP)and inner(IP)CuO_(2)planes is determined.Charge distribution imbalance between the OP and IP CuO_(2)planes is quantified,showing enhanced disparity with increasing doping.Nodal band dispersions demonstrate a prominent kink at~94 meV in the IP band,attributed to the unique Cu coordination in the IP plane,while a weaker~60 meV kink is observed in the OP band.The nodal Fermi velocity of both OP and IP bands is nearly constant at~1.62 eV·A independent of doping.These results provide important information to understand the origin of high Tcand superconductivity mechanism in high temperature cuprate superconductors.
