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Parametric study of ultra-intense laser interaction with uniform and nano-porous near-critical plasmas
摘要： Responses of the uniform near-critical plasma (UNCP) and nano-porous near-critical plasma (NPNCP) upon interaction with a short-intense laser have been scrutinized using two-dimensional (2D) particle-in-cell simulations. Maximum proton energy variation by the deposition of uniform and nano-porous layers in front of a solid target for a wide range of laser intensities (normalized amplitude a0 = 5–25) and average densities of the front layer ne = 0.3 ? 3nc (where nc is the critical density) has been parametrically studied. It is found that the proton maximum energy for the front layers with sub-10 μm thicknesses is independent of the target porosity and density. However, in the relatively thick targets, the nano-porous structure decreases the laser energy absorption and, subsequently, the maximum proton energy compared to the uniform one. The results indicate that by employing UNCPs instead of NPNCPs, at the moderate laser intensity, the maximum proton energy reveals a 23% enhancement. This increment could be explained by rapid self-focusing of the laser pulse and dominant direct laser electron acceleration regime on the well-formed plasma channel in the UNCP layer. However, in the case of NPNCPs, the laser scattering from the plasma structure makes it less intense and more disordered, which influences the efficient laser energy coupling to the electrons.
关键词： proton acceleration,near-critical plasmas,particle-in-cell simulations,ultra-intense laser,laser-plasma interaction
更新于2025-09-23 15:21:01
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Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses
摘要： We investigate the numerical stability of time-dependent coupled-cluster theory for many-electron dynamics in intense laser pulses, comparing two coupled-cluster formulations with full configuration interaction theory. Our numerical experiments show that orbital-adaptive time-dependent coupled-cluster doubles (OATDCCD) theory offers significantly improved stability compared with the conventional Hartree-Fock-based time-dependent coupled-cluster singles-and-doubles (TDCCSD) formulation. The improved stability stems from greatly reduced oscillations in the doubles amplitudes, which, in turn, can be traced to the dynamic biorthonormal reference determinants of OATDCCD theory. As long as these are good approximations to the Brueckner determinant, OATDCCD theory is numerically stable. We propose the reference weight as a diagnostic quantity to identify situations where the TDCCSD and OATDCCD theories become unstable.
关键词： time-dependent coupled-cluster theory,OATDCCD,Brueckner determinant,TDCCSD,intense laser pulses,numerical stability,many-electron dynamics
更新于2025-09-23 15:21:01
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Petapascal Pressure Driven by Fast Isochoric Heating with a Multipicosecond Intense Laser Pulse
摘要： Fast isochoric laser heating is a scheme to heat matter with a relativistic intensity (> 1018 W=cm2) laser pulse for producing an ultrahigh-energy-density (UHED) state. We have demonstrated an efficient fast isochoric heating of a compressed dense plasma core with a multipicosecond kilojoule-class petawatt laser and an assistance of externally applied kilotesla magnetic fields for guiding fast electrons to the dense plasma. A UHED state of 2.2 PPa is achieved experimentally with 4.6 kJ of total laser energy that is one order of magnitude lower than the energy used in the conventional implosion scheme. A two-dimensional particle-in-cell simulation confirmed that diffusive heating from a laser-plasma interaction zone to the dense plasma plays an essential role to the efficient creation of the UHED state.
关键词： magnetized fast isochoric heating,petapascal pressure,Fast isochoric laser heating,ultrahigh-energy-density state,multipicosecond intense laser pulse
更新于2025-09-23 15:19:57
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The effect of target thickness on the efficiency of high-order harmonics generated from laser-driven overdense plasma target
摘要： In this paper, we analytically and numerically studied the impact of the target thickness on the efficiency of laser-plasma based high-order harmonics generation (HHG). The optimal parametric region is acquired where the laser normalized amplitude a0, the target density ne and thickness d0 satisfy the relation: a0nc/ne < d0 < a0nc/2ne. In this region, the laser can partially penetrate the target, leading to efficient acceleration of the target. Meanwhile, the target is thick enough to oscillate along the rising edge of the laser without being broken, which guarantees the occurrence of HHG. Both one-dimensional and two-dimensional particle-in-cell simulation results verify our optimal target thickness theory, and a single attosecond pulse with I = 3.0 × 1020 W cm?2 is generated under the driving of 8.6 × 1020 W cm?2, which is several hundred times more intense than that from a thick target.
关键词： the Doppler effect,conversion efficiency,high-order harmonics,intense laser
更新于2025-09-23 15:19:57
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Spectral splitting and phase matching of the macroscopic high-order harmonic generation in intense laser fields
摘要： We theoretically investigate the macroscopic high-order harmonic generation in argon gaseous medium by numerically solving the three-dimensional macroscopic propagation equation, and the results show that the harmonic spectral and spatial profiles of harmonics are gradually splitting with the increasing of the driving laser intensity. This splitting is mainly due to the distortions which the driving field suffers during propagation and the consequence is also on phase matching. To illustrate the physical mechanisms of harmonic splitting, a theoretical analysis of the phase matching is presented. The harmonic spectra from different focus positions reveal that the split is dependent on the focus-gas-jet relative position. Moreover, we demonstrate that the spectral splitting of high harmonics can hardly be observed for neon gas jet due to the high ionization energy.
关键词： phase matching,high-order harmonic generation,intense laser fields,macroscopic propagation,spectral splitting
更新于2025-09-23 15:19:57
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Polarization-dependent high-intensity Kapitza-Dirac effect in strong laser fields
摘要： We study the de?ection of photoelectrons in intense elliptically polarized standing light waves, known as the high-intensity Kapitza-Dirac effect. In order to compute the longitudinal momentum transfer to the photoelectron in above-threshold ionization, we utilize a complete description of the quantum dynamics in the spatially dependent ?eld of the standing light wave. We propose experimental conditions under which low-energy photoelectrons can be generated with remarkably high longitudinal momenta that can be controlled via the polarization of the standing wave. We expect that future experimental realizations will provide additional insights into the momentum transfer in intense laser-atom interactions.
关键词： intense laser ?elds,Kapitza-Dirac effect,momentum transfer,photoelectrons,polarization
更新于2025-09-23 15:19:57
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[IEEE 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - Barcelona, Spain (2019.9.2-2019.9.6)] 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - Propagation of Laser-Driven Electromagnetic Pulses in Laser Target Areas
摘要： During high intense laser target interaction a strong electromagnetic pulse (EMP) is generated which can potentially disturb the well performing of the experiment. The electromagnetic interference (EMI) due to the EMP not only affects devices present in the vacuum chamber but also in the target area where it may compromise the performance or operation of electronics and device controllers. In this work we report the measurements of EMP inside the laser target area at Centro de Laseres Pulsados (CLPU) during high intense laser-target interaction experiments. The experimental results show how the amplitude and spectrum of the EMP in the target area is different from the one inside the target chamber (TC). At last Finite element method (FEM) simulation results are shown and compared with experimental results.
关键词： laser-plasma interaction,Electromagnetic interference (EMI),High Intense laser,Electromagnetic Pulse (EMP),Finite Element Method (FEM) simulations
更新于2025-09-16 10:30:52
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The transition from double to single quantum dot induced by THz laser field
摘要： The combined influence of an intense laser field and a homogeneous magnetic field is considered on laterally coupled double quantum dot with isotropic and anisotropic parabolic confinement. It is shown that intense laser field can recover typical properties to a single quantum dot: it creates Fock–Darwin states in a double quantum dot with anisotropic confinement. Also, the laser and the magnetic field effects on the intraband absorption spectrum reveal blueshift if the laser field is increased and redshift with the gain of the magnetic field.
关键词： Double quantum dot,Fock–Darwin states,Intense laser field,Magnetic field,Intraband absorption
更新于2025-09-16 10:30:52
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Ultrafast Structural Dynamics of Nanoparticles in Intense Laser Fields
摘要： Femtosecond laser pulses have opened new frontiers for the study of ultrafast phase transitions and nonequilibrium states of matter. In this Letter, we report on structural dynamics in atomic clusters pumped with intense near-infrared (NIR) pulses into a nanoplasma state. Employing wide-angle scattering with intense femtosecond x-ray pulses from a free-electron laser source, we find that highly excited xenon nanoparticles retain their crystalline bulk structure and density in the inner core long after the driving NIR pulse. The observed emergence of structural disorder in the nanoplasma is consistent with a propagation from the surface to the inner core of the clusters.
关键词： x-ray scattering,nanoparticles,nanoplasma,intense laser fields,ultrafast structural dynamics
更新于2025-09-11 14:15:04
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Electron–Ion Recombination Effect on Electron Acceleration by an Intense Laser Pulse
摘要： Electron–ion recombination effect on electron acceleration by a high-intensity laser pulse propagating through a tunnel ionizing gas is investigated in order to observe the actual electron energy gain during acceleration. An intense short-pulse laser with a Gaussian radial pro?le propagates through a vacuum followed by gas. The point at which the peak of the pulse interacts with the electron is the initial point of the gas region. Tunnel ionization causes defocusing of the laser pulse due to high-density plasma formation on the propagation axis. The electron experiences an additional acceleration during the trailing part of the pulse and, thus, gains net energy. In the presence of electron–ion recombination, the laser pulse focuses more, and hence, the net energy gain is affected signi?cantly for speci?c parameters region. A model that self-consistently evolves the laser electron acceleration as it ionizes a neutral gas is presented. The model incorporates the electron–ion recombination effects for multiple ionization stage and for tempospatial variations in the neutral gas density appropriate for studying gas-jet system. The electron energy gain during acceleration is calculated in He gas, where the conditions are appropriate for recombination. It is found that for a given laser intensity, there is always an optimal spot size and focal position with respect to the gas jet, which minimizes the refraction and maximizes the acceleration length for higher energy gain of the electrons. The inclusion of electron–ion recombination is more realistic if the pulse duration is longer in a laser–gas-jet experiment.
关键词： Electron acceleration,gas-jet,energy gain,electron–ion recombination,intense laser pulse
更新于2025-09-11 14:15:04