A5047037350- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- Plasma Diagnostics and Applications
- Dust and Plasma Wave Phenomena
- Magnetic confinement fusion research
- Electrohydrodynamics and Fluid Dynamics
- High-pressure geophysics and materials
- Atomic and Molecular Physics
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Horticultural and Viticultural Research
- Gyrotron and Vacuum Electronics Research
- Laser Design and Applications
- Ion-surface interactions and analysis
- Laser Material Processing Techniques
- Advanced Data Storage Technologies
- Particle Accelerators and Free-Electron Lasers
- Fusion materials and technologies
- Advanced Fiber Laser Technologies
- Electromagnetic Simulation and Numerical Methods
- Nuclear Physics and Applications
- Plasma Applications and Diagnostics
- Quantum optics and atomic interactions
- Lightning and Electromagnetic Phenomena
Centre National de la Recherche Scientifique
2013-2024
École Polytechnique
2013-2024
Centre de Physique Théorique
2008-2024
Centre de Physique Théorique
2009-2024
Université Paris-Saclay
2017
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
1990-2008
Laboratoire d'Informatique de l'École Polytechnique
1999
Faculty of 1000 (United Kingdom)
1956-1957
City, University of London
1956-1957
The Edgbaston Hospital
1956
Stationary plasma thrusters are devices that use crossed electric and magnetic fields to accelerate ions high velocities. Ions created by collisional ionization of a propellant gas with electrons injected from hollow cathode external the thruster. A major issue is electron transport through field. It known exceed considerably values predicted classical theory. Various 2D models have shown wall collisions, which often been invoked as origin this anomalous transport, in fact insufficient....
A systematic study of a high-frequency electron drift instability is presented. It has very large wave numbers corresponding to wavelengths close the gyroradius. The three-dimensional dispersion relation derived for model crossed electric and magnetic field configuration existing in Hall thruster. shown that develops packets oblique unstable modes perpendicular field. evolution also studied distorted distribution functions obtained particle-in-cell simulations.
The interaction of laser pulses with thin grating targets, having a periodic groove at the irradiated surface, is experimentally investigated. Ultrahigh contrast ($\ensuremath{\sim}{10}^{12}$) allow us to demonstrate an enhanced laser-target coupling for first time in relativistic regime ultrahigh intensity $>{10}^{19}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$. A maximum increase by factor 2.5 cutoff energy protons produced target normal sheath acceleration observed respect plane around...
The formation and evolution of density channels created by the interaction a short bright (600 fs, $5\ifmmode\times\else\texttimes\fi{}{10}^{18}\mathrm{W}{\mathrm{cm}}^{\ensuremath{-}2}\ensuremath{\mu}{\mathrm{m}}^{2}$) laser pulse with preformed plasma are studied means experiments 2D particle-in-cell (PIC) simulations. Hollow observed interferometry, fast radial expansion $(5\ifmmode\times\else\texttimes\fi{}{10}^{8}\mathrm{cm}/\mathrm{s})$ is measured. Magnetic fields around 50 MG...
The energy transfer from a long (3.5 ps) pump pulse to short (400 fs) seed due stimulated Brillouin backscattering in the strong-coupling regime is investigated. two pulses, both at same wavelength of 1.057 microm are quasicounterpropagating preformed underdense plasma. Relative amplification factors for up 32 obtained. maximum obtained amplified 60 mJ. Simulations agreement with experimental results and suggest paths further improvement scheme.
With the help of an implicit particle-in-cell code, we have shown in a previous paper that electron-cyclotron drift instability was able to induce anomalous conductivity as well heating. As such it can be major actor among mechanisms involved operation Hall thrusters. However, experimental results show nature wall material has significant effect on behavior thruster. The purpose this is study plasma-wall interaction case where plasma heated self-consistently by electrostatic fluctuations...
A large amplitude electromagnetic wave propagating in a plasma is known to be subject severe modulational and Raman instabilities. Previous works were devoted the weakly relativistic limit applied mainly cold underdense plasma. One extends these include fully for circularly polarized light which one derives dispersion relation one-dimensional The characteristics of instabilities are also calculated case where classically overdense, with 1<(ωp/ω0)2<γ, ωp frequency, ω0 laser γ...
Due to relativistic effects, a large amplitude electromagnetic wave can propagate in classically overdense plasma with ω2p≳ω2≳ω2p/γ, where ωp is the frequency, ω laser and γ factor of an electron field. Particle-in-cell simulations are used study interaction ultrahigh intensity pulse normal incidence on one-dimensional preformed layer. Both electrons ions dynamics included. The width layer 10 30 μm characterized by (ωp/ω)2=1.5. During penetration longitudinal electric field generated. It...
We study the angular distribution of relativistic electrons generated through laser-plasma interaction with pulse intensity varying from ${10}^{18}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$ up to ${10}^{21}\text{ and plasma density ranging 10 times 160 critical help 2D 3D particle-in-cell simulations. This gives clear evidence that divergence beam is an intrinsic property a laser sharp gradient. It entirely due excitation large static magnetic fields in layer interaction. The energy...
This paper presents recent efforts to better understand and quantify charged particle transport in Hall effect thrusters (HETs). Particle-in-cell (PIC) models, hybrid laser induced fluorescence (LIF) measurements collective scattering (CS) experiments are combined get a insight into anomalous electron HETs increase the predictive capabilities of simulation codes.PIC models have demonstrated that plasma turbulence associated with development high frequency, short wavelength azimuthal...
A comprehensive examination of the interaction a picosecond-long ignition pulse on high-density (40 times critical density) pellets using two-dimensional particle-in-cell model is described. The global geometry consists 50 mum diameter pellet surrounded by corona which isolated vacuum region from boundary. For cone-attached targets, as much 67% incident laser energy absorbed with 12% sent forward fast electrons in 23 degrees cone. current filaments are driven Weibel instability forward-going...
The axial velocity of singly charged xenon ion is determined by means laser induced fluorescence spectroscopy at the exhaust a PPS100-LM Hall effect thruster analyzing Doppler shifted spectral profile 834.72 nm Xe+ line. Measurements are carried out both inside and outside channel. Ion distribution functions (VDF) used to compute accelerating potential. It shown that such potential can in fact be defined several ways due overlap between ionization acceleration layers, which translates into...
A detailed description of stimulated Raman backscattering and related processes for the purpose inertial confinement fusion requires multi-dimensional kinetic simulations a full speckle in high-temperature, large-scale, inhomogeneous plasma. In particular shock-ignition scheme operating at high laser intensities, aspects are predominant. High- (Iλo2~5×1015Wμm2/cm2) as well low-intensity (Iλo2~1015Wμm2/cm2) cases show predominance collisionless, collective interaction. While two-plasmon decay...
Two-plasmon-decay (TPD) instability is investigated for conditions relevant the shock-ignition (SI) scheme of inertial confinement fusion. Two-dimensional particle-in-cell simulations show that in a hot, large-scale plasma, TPD develops concomitance with stimulated Raman scattering (SRS). It active only during first picosecond interaction, and then it rapidly saturated due to plasma cavitation. TPD-excited waves extend small wavelengths, above standard Landau cutoff. The hot electron...
Experiments have been performed evidencing significant stimulated Raman sidescattering (SRS) at large angles from the density gradient. This was achieved in long scale-length high-temperature plasmas which two beams couple to same scattered electromagnetic wave further demonstrating for first time this multiple-beam collective SRS interaction. The nature of coupling and amplification gradient increase global losses produce light novel directions out planes incidence beams. These findings...
Transmission of a subpicosecond relativistic laser pulse is observed through solid foils and preformed overcritical plasmas. rates near 10% for densities above $10\ifmmode\times\else\texttimes\fi{}{n}_{c}$ are measured. A moderately strong threshold in intensity found order to observe this effect. The experimental results as well preliminary particle-in-cell simulations suggest that thin the transmission explicable by rapid heating expansion transmissive conditions during pulse. Self-induced...
Plasma simulations are often rendered challenging by the disparity of scales in time and space which must be resolved. When these disparities distinctive zones simulation domain, a method has proven to effective other areas (e.g., fluid dynamics simulations) is mesh refinement technique. A brief discussion challenges posed coupling this technique with plasma particle-in-cell given, followed presentation examples application heavy ion fusion related fields illustrate effectiveness approach....
Harmonics of the laser light have been observed from rear side solid targets irradiated by a beam at relativistic intensities. This emission evidences acceleration subfemtosecond electron bunches pulse in front target. These emit coherent transition radiation (CTR) when passing through back surface The spectral features signal recorded for thicknesses up to several hundred microns are consistent with electrons being accelerated both electric field—via vacuum heating and/or resonance...
Two-dimensional (2D) particle-in-cell numerical simulations of the interaction between a high-intensity short-pulse p-polarized laser beam and an overdense plasma are presented. It is shown that, under appropriate physical conditions, surface wave can be resonantly excited by wave, leading to strong relativistic electron acceleration together with dramatic increase, up 70%, light absorption plasma. Purely 2D effects contribute enhancement acceleration. also found that angular distribution...
The one-dimensional expansion of a plasma slab is studied using kinetic description the electrons based on an adiabatic invariant. distribution function determined at any time and position. Solution Poisson equation then enables us to determine electric potential ion acceleration. Special attention devoted disassembly which appears shorter than expected, due distortion electron function. spatial structures densities velocities are presented, together with prediction maximum velocity. model...
The effect of ion sound wave (ISW) nonlinearities on the stimulated Brillouin scattering (SBS) in long plasmas is investigated within framework Korteweg–de Vries–Maxwell equations. nonlinear evolution driven ISW results localization density a scale shorter than wavelength (λs) resonant satisfying SBS three-wave matching conditions. Since transverse amplitudes vary much longer scale, local–global modeling proposed which this separation exploited. local part procedure includes solution to...
We report on highly time- and space-resolved measurements of the evolution electron plasma waves driven by stimulated Raman scattering a picosecond, single laser speckle propagating through preformed underdense plasma. Two-dimensional Thomson scatter spectra indicate that dominant have significant transverse components. These results are supported particle-in-cell simulations which pinpoint role wave front bowing secondary nonlinear electrostatic instabilities in waves.
The efficiency of laser overdense plasma coupling via surface wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed over a wide range pulse intensity from 1015 to 1020 W cm−2 μm2 with electron density ranging 25 100nc describe the interaction grating target where condition fulfilled. numerical studies confirm an efficient enhancement absorption up 75%. also show presence localized, quasi-static magnetic field at surface. Two regimes identified for low...
The autoresonant behavior of Langmuir waves excited by stimulated Raman scattering (SRS) is clearly identified in particle-in-cell (PIC) simulations an inhomogeneous plasma. As previously shown via a 3-wave coupling model [T. Chapman et al., Phys. Plasmas 17, 122317 (2010)], weakly kinetic effects such as trapping can be described amplitude-dependent frequency shift that compensates the dephasing resonance SRS due to inhomogeneity. autoresonance (AR) leads phase locking and growth wave...
Collective Thomson scattering experiments reveal the presence of high-frequency, axial electron density fluctuations at millimetric wavelengths in Hall thruster plasma. The properties these are investigated experimentally and via linear kinetic theory. relative drift electrons ions direction is found to be insufficient cause excitation observed mode. Instead, mode determined a two-stream instability arising due velocity difference between singly doubly charged ion populations plume.