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A selection of theoretical results in the context of laser-plasma interaction and inertial fusion
摘要： I recall a selection of my results of the last 40 years. I first present a theoretical model of absorption of laser light by a plasma, with an emphasis on its dependence on the laser intensity and wavelength. A second topic concerns the nonlinear and nonlocal electron transport in steep temperature gradients. Thirdly, I present the work on the propagation of a short intense laser pulse in tenuous plasmas. Finally, I discuss the plasma expansion into a vacuum, in particular the structure of the ion front and the prediction of the maximum velocity attained by the ions in the expansion.
关键词： thermal conduction,plasma expansion,collisional absorption,inertial fusion,laser-plasma interaction
更新于2025-09-16 10:30:52
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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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Application of harmonics imaging to focal spot measurements of the “PETAL” laser
摘要： By using numerical simulations and experimental campaigns on a small-scale laser facility, the concept of the focal spot imaging on harmonics of laser frequency is developed and implemented on the Laser MegaJoule (LMJ)/PETawatt Aquitaine Laser (PETAL) facility. The Two/Three ω Imaging System was activated and validated during the first 2017–2019 interaction campaigns of PETAL on the LMJ. It provides major information on focal spot characteristics on a target. Such an approach could be easily applied to any high-intensity facility in the relativistic intensity regime (>1018 W cm?2).
关键词： PETAL laser,harmonics imaging,high-intensity laser-plasma interaction,focal spot measurements
更新于2025-09-16 10:30:52
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Dependence of laser-induced fluorescence on exciting-laser power: partial saturation and laser – plasma interaction
摘要： In recent publications on laser-induced ?uorescence (LIF), the measurements are usually constricted to the region of weak exciting-laser power – the so called linear LIF. In this work, a practical formula describing the dependence of partially saturated ?uorescence on the exciting-laser power is derived, together with practical implementation suggestions and comments on its limitations. In the conclusion, the practical formula F (EL) = α EL / (1 + β EL) is proposed with the limitation for validity β EL ≤ 0.4, where α EL is the hypothetical linear ?uorescence without saturation e?ects, and a more general formula is derived, which is valid for higher values of β EL as well. Extending the range of exciting laser power to the region of partial saturation enhances the signal-to-noise ratio. Such measurements in a surface dielectric barrier discharge further reveal discharge disruption by photoelectrons emitted from the dielectric surface. Methods of control and solution of this problem are discussed.
关键词： dielectric barrier discharge,laser – plasma interaction,partial saturation,laser-induced ?uorescence,signal-to-noise ratio
更新于2025-09-16 10:30:52
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Optimization of laser parameters for proton acceleration using double laser pulses in TNSA mechanism
摘要： The energy of protons accelerated by ultra-intense lasers in the target normal sheath acceleration (TNSA) mechanism can be greatly enhanced by the laser parameter optimization. We propose to investigate the optimization of laser parameters for proton acceleration using double laser pulses in TNSA mechanism. The sheath field generation at the rear side of the target is significantly affected by the introduction of second laser pulse in TNSA mechanism, and consequently, the energy of the accelerated protons is also modified. The second laser pulse was introduced with different delays to study its impact on proton acceleration. Our study shows that the interplay of laser intensity and pulse duration of both laser pulses affects the proton acceleration. It was found that the proton maximum energy is the function of both laser intensity and pulse duration. A number of simulations have been performed to obtain maximum proton energy data under different combinations of laser intensity and pulse duration for the two laser pulses. The simulation results account for the underline physics for the proton bunch energy and the sheath field as a function of pulse intensity and pulse delay.
关键词： proton acceleration,ultrashort laser pulse,Laser–plasma interaction
更新于2025-09-16 10:30:52
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Attosecond pulse generation by relativistic flying mirrors in laser-plasma interaction: Effect of plasma density and driver amplitude on the generated pulse
摘要： The generation of high-intensity attosecond pulses by the interaction of two counterpropagating short laser pulses with underdense plasma is investigated. By using parallel fully kinetic particles in cell simulation, which shows the formation of relativistic ?ying mirrors in the wake wave of the intense driver laser pulse and the focusing re?ection of the weak source pulse, it is demonstrated that intense attosecond pulses can be produced under the optimized conditions of plasma density and driver laser amplitude according to the relativistic similarity theory. In addition, it is shown that the frequency of the source pulse is upshifted by a factor from 10 to 80 corresponding to a re?ected radiation wavelength from 20 to 164 nm which lies in the extreme ultraviolet region, while most of the energy lies around a frequency upshift of 20, in agreement with the measured Lorentz factor. The intensity of the main attosecond pulse is two orders higher than the source pulse intensity.
关键词： plasma density,driver amplitude,attosecond pulse generation,relativistic flying mirrors,laser-plasma interaction
更新于2025-09-12 10:27:22
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Plasma optics in the context of high intensity lasers
摘要： The use of plasmas provides a way to overcome the low damage threshold of classical solid-state based optical materials, which is the main limitation encountered in producing and manipulating intense and energetic laser pulses. Plasmas can directly amplify or alter the characteristics of ultra-short laser pulses via the three-wave coupling equations for parametric processes. The strong-coupling regime of Brillouin scattering (sc-SBS) is of particular interest: recent progress in this domain is presented here. This includes the role of the global phase in the spatio-temporal evolution of the three-wave coupled equations for backscattering that allows a description of the coupling dynamics and the various stages of amplification from the initial growth to the so-called self-similar regime. The understanding of the phase evolution allows control of the directionality of the energy transfer via the phase relation between the pulses. A scheme that exploits this coupling in order to use the plasma as a wave plate is also suggested.
关键词： Brillouin scattering,wave plate,high intensity lasers,Plasma optics,laser-plasma interaction
更新于2025-09-12 10:27:22
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THz Generation from Relativistic Plasmas Driven by Near- to Far-Infrared Laser Pulses
摘要： Terahertz pulse generation by ultraintense two-color laser fields ionizing gases with near- to far-infrared carrier wavelength is studied from particle-in-cell simulations. For a long pump wavelength (10.6 μm) promoting a large ratio of electron density over critical, photoionization is shown to catastrophically enhance the plasma wakefield, causing a net downshift in the optical spectrum and exciting THz fields with tens of GV/m amplitude in the laser direction. This emission is accompanied by coherent transition radiation (CTR) of comparable amplitude due to wakefield-driven electron acceleration. We analytically evaluate the fraction of CTR energy up to 30% of the total radiated emission including the particle self-field and numerically calibrate the efficiency of the matched blowout regime for electron densities varied over three orders of magnitude.
关键词： photoionization,laser-plasma interaction,plasma wakefield,Terahertz,coherent transition radiation,particle-in-cell simulations
更新于2025-09-12 10:27:22
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Enhancement of target normal sheath acceleration in laser multi-channel target interaction
摘要： Target-normal sheath acceleration (TNSA) of ions by >100-fs relativistic laser pulses irradiating a multichannel target consisting of a row of parallel long wires and a plane back foil is studied. Two-dimensional particle-in-cell simulations show that the laser light pulls out from the wires a large number of dense hot attosecond electron bunches, which are synergetically accelerated forward by the relativistic ponderomotive force of the laser as well as the longitudinal electric field of a transverse magnetic mode that is excited in the vacuum channels between the wires. These electrons are characterized by a distinct two-temperature energy spectrum, with the temperature of the more energetic electrons close to twice the ponderomotive potential energy. After penetrating through the foil, they induce behind its rear surface a sheath electric field that is both stronger and frontally more extended than that without the channels. As a result, the TNSA ions have much higher maximum energy and the laser-to-ion energy conversion efficiency is also much higher. It is found that a laser of intensity 1.37 × 1020 W/cm2, duration 165 fs, and energy 25.6 J can produce 85 MeV protons and 31 MeV/u carbon ions, at 30% laser-to-ion energy conversion efficiency. The effects of the channel size and laser polarization on the TNSA ions are also investigated.
关键词： laser-plasma interaction,ion acceleration,Target-normal sheath acceleration,particle-in-cell simulations,TNSA,laser-to-ion energy conversion efficiency
更新于2025-09-12 10:27:22
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Particle-in-cell simulations of density peak formation and ion heating from short pulse laser-driven ponderomotive steepening
摘要： We use two-dimensional particle-in-cell (PIC) simulations and simple analytic models to investigate the laser-plasma interaction known as ponderomotive steepening. When normally incident laser light reflects at the critical surface of a plasma, the resulting standing electromagnetic wave modifies the electron density profile via the ponderomotive force, which creates peaks in the electron density separated by approximately half of the laser wavelength. What is less well studied is how this charge imbalance accelerates ions toward the electron density peaks, modifying the ion density profile of the plasma. Idealized PIC simulations with an extended underdense plasma shelf are used to isolate the dynamics of ion density peak growth for a 42 fs pulse from an 800 nm laser with an intensity of 1018 W cm?2. These simulations exhibit sustained longitudinal electric fields of 200 GV m?1, which produce countersteaming populations of ions reaching a few kilo-electron-volt in energy. We compare these simulations to theoretical models, and we explore how ion energy depends on factors such as the plasma density and the laser wavelength, pulse duration, and intensity. We also provide relations for the strength of longitudinal electric fields and an approximate time scale for the density peaks to develop. These conclusions may be useful for investigating the phenomenon of ponderomotive steepening as advances in laser technology allow shorter and more intense pulses to be produced at various wavelengths. We also discuss the parallels with other work studying the interference from two counterpropagating laser pulses.
关键词： laser-plasma interaction,ion heating,ponderomotive steepening,density peak formation,particle-in-cell simulations
更新于2025-09-12 10:27:22