Showing papers by "Gerard Mourou published in 2009"

Hole Boring in a DT Pellet and Fast-Ion Ignition with Ultraintense Laser Pulses

Abstract: Recently achieved high intensities of short laser pulses open new prospects in their application to hole boring in inhomogeneous overdense plasmas and for ignition in precompressed DT fusion targets. A simple analytical model and numerical simulations demonstrate that pulses with intensities exceeding 10;{22} W/cm;{2} may penetrate deeply into the plasma as a result of efficient ponderomotive acceleration of ions in the forward direction. The penetration depth as big as hundreds of microns depends on the laser fluence, which has to exceed a few tens of GJ/cm;{2}. The fast ions, accelerated at the bottom of the channel with an efficiency of more than 20%, show a high directionality and may heat the precompressed target core to fusion conditions.

Dynamics of emitting electrons in strong laser fields

Abstract: A new derivation of the motion of a radiating electron is given, leading to a formulation that differs from the Lorentz–Abraham–Dirac equation and its published modifications. It satisfies the proper conservation laws. Particularly, it conserves the generalized momentum, eliminating the symmetry-breaking runaway solution. The equation allows a consistent calculation of the electron current, the radiation effect on the electron momentum, and the radiation itself, for a single electron or plasma electrons in strong electromagnetic fields. The equation is then applied to a simulation of a strong laser pulse interaction with a plasma target. Some analytical solutions are also provided.

Quasimonoenergetic electron beams with relativistic energies and ultrashort duration from laser-solid interactions at 0.5 kHz.

Abstract: We investigate the production of electron beams from the interaction of relativistically-intense laser pulses with a solid-density SiO2 target in a regime where the laser pulse energy is -mJ and the repetition rate -kHz. The electron beam spatial distribution and spectrum were investigated as a function of the plasma scale length, which was varied by deliberately introducing a moderate-intensity prepulse. At the optimum scale length of λ/2, the electrons are emitted in a collimated beam having a quasimonoenergetic distribution that peaked at -0.8MeV. A highly reproducible structure in the spatial distribution exhibits an evacuation of electrons along the laser specular direction and suggests that the electron beam duration is comparable to that of the laser pulse. Particle-in-cell simulations which are in good agreement with the experimental results offer insights on the acceleration mechanism by the laser field. © 2009 The American Physical Society.

Dynamics of Emitting Electrons in Strong Electromagnetic Fields

Abstract: We derive a modified non-perturbative Lorentz-Abraham-Dirac equation. It satisfies the proper conservation laws, particularly, it conserves the generalized momentum, the latter property eliminates the symmetry-breaking runaway solution. The equation allows a consistent calculation of the electron current, the radiation effect on the electron momentum, and the radiation itself, for a single electron or plasma electrons in strong electromagnetic fields. The equation is applied to a simulation of a strong laser pulse interaction with a plasma target. Some analytical solutions are also provided.

Terahertz pulse imaging for tree-ring analysis: a preliminary study for dendrochronology applications

Abstract: Time-domain terahertz reflection imaging is presented as a novel method of measuring otherwise inaccessible tree rings in wooden cultural heritage for the purpose of tree-ring crossdating. Axial and lateral two-dimensional terahertz images of obscured ring patterns are statistically validated with respect to their corresponding optical photographs via adapted dendrochronological methods. Results are compared to similar analysis of x-ray images of a wood specimen.

Ponderomotive ion acceleration in dense plasmas at super-high laser intensities

Abstract: Short laser pulses at super-high intensities such as those proposed in the Extreme Light Infrastructure (ELI) project open new prospects for efficient acceleration of ions in overdense plasmas. A simple analytical model and numerical simulations demonstrate that pulses with intensities exceeding 10 22 W/cm2 may efficiently accelerate ions to high energies up to a few GeV. Maximum ion energy and the energy spectrum of the accelerated ions can be tuned by an appropriate choice of laser pulse intensity and duration at a given plasma density distribution. © 2009 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

The Extreme Light Infrastructure Project ELI and Its Prototype APOLLON/ILE: “The Associated Laser Bottlenecks”

Abstract: We will present the ELI Project consisting in a 200PW laser based high intensity physics users infrastructure. A French single beamline laser prototype called ILE/APOLLON is presently under construction. Associated technological bottlenecks will be described.

Radiation back-reaction in relativistically strong and QED-strong laser fields

Abstract: The emission from an electron in the field of a relativistically strong laser pulse is analyzed. At the pulse intensities of \ge 10^{22} W/cm^2 the emission from counter-propagating electrons is modified by the effects of Quantum ElectroDynamics (QED), as long as the electron energy is sufficiently high: E \ge 1 GeV. The radiation force experienced by an electron is for the first time derived from the QED principles and its applicability range is extended towards the QED-strong fields.

Device for generating a short duration laser pulse

Abstract: An embodiment relates to a device for generating a short duration laser pulse, which comprises: means for generating a laser beam and for filtering same, arranged in such a way as to generate an input laser beam providing an input laser pulse; a transparent slide comprising a non-linear scattering material; the laser generation means being arranged so that the slide widens the spectrum of the input laser pulse by phase self-modulation in order to generate a wide-spectrum laser pulse; compression means adapted for compressing the wide-spectrum laser pulse in order to generate a short duration laser pulse; wherein the laser generation means are arranged so that the input beam is spatially uniform on the transparent slide and has a break integral B lower than three when the input beam passes through the transparent slide.

Dispositif de generation d'une impulsion laser à duree reduite

Abstract: L'invention se rapporte a un dispositif (1) de generation d'une impulsion laser a duree reduite (7) comprenant : - des moyens (2) de generation d'un faisceau laser (8) et de filtrage de celui-ci (9) agences pour generer un faisceau laser d'entree (3) fournissant une impulsion laser d'entree; - une lame transparente (4) comprenant un materiau non-lineaire dispersif; - les moyens de generation laser etant agences pour que la lame elargisse le spectre de l'impulsion laser d'entree par auto- modulation de phase de sorte a generer une impulsion laser a spectre elargi (5); - des moyens de compression (6) agences pour compresser l'impulsion laser a spectre elargi de sorte a generer l'impulsion laser a duree reduite (7), le dispositif etant caracterise en ce que les moyens de generation laser sont agences pour que le faisceau d' entree (3) soit spatialement uniforme sur la lame transparente (4) et ait une integrale de rupture B inferieure a trois lorsqu'il traverse la lame transparente (4).

The Radiation Reaction Effect on Electrons at Super-High Laser Intensities with Application to Ion Acceleration

Abstract: At super‐high laser intensities the radiation back reaction on electrons becomes so significant that its influence on laser‐plasma interaction cannot be neglected while simulating these processes with particle‐in‐cell (PIC) codes. We discuss a way of taking the radiation effect on electrons into account and extracting spatial and frequency distributions of the generated high‐frequency radiation. We also examine ponderomotive acceleration of ions in the double layer created by strong laser pulses and we compare an analytical description with PIC simulations as well. We discuss: (1) non‐stationary features found in simulations, (2) electron cooling effect due to radiation losses, and (3) the limits of the analytical model.

Perspectives of XUV sources development on LASERIX facility, ILE, and ELI

Abstract: In this paper we present the perspectives of the development of the XUV laser sources using High-power laser facilities. We focus our paper on the present statuts of the LASERIX facility and especially its role in the development of the XUV laser sources considering the French "Institut de la Lumiere Extreme" (ILE) and the potential European project Extreme Light Infrastructure (ELI).

Terahertz metrology of tree rings for dendrochronology and cultural heritage applications

Abstract: Terahertz imaging will be presented as a novel method of nondestructively measuring otherwise inaccessible tree-rings for the purpose of dendrochronologically cross-dating cultural heritage artifacts. Wood specimens were measured using time-domain terahertz pulse reflectometry. Two-dimensional images of tree-rings were generated through analysis of both time- and frequency-domain terahertz signals, which changed proportionally to the variations in wood density. Terahertz pulse separation enabled wood specimens with at least two layers of coatings (primer and/or paint) to be measured and the terahertz images were quantitatively compared to the optical photographs of related, uncoated specimen. Tree-ring series and timelines were obtained for each terahertz image with respect to the source (reference) ring series. Short ring width blocks were aligned to the reference series and combined to create an extended timeline for each terahertz image. It was determined that while spatial resolution may be improved with analysis at high frequencies, the lower signal to noise reduces the precision of the ring measurement. Constructing longer timelines from ring blocks, significantly improves the overall quality of a match.