Three-dimensional Maxwell-Bloch calculation of the temporal profile of a seeded soft x-ray laser pulse

International audienceWe present three-dimensional modeling of amplification of a high-order harmonic seed by a soft x-ray laser plasma. The time-dependent evolution of the x-ray signal is determined from a fully dynamic Maxwell-Bloch calculation. At high seed intensities , a simplified one-dimensional calculation leads to strong Rabi-like temporal oscillations of the output signal. However, such oscillations have not been observed experimentally. Our three-dimensional calculations demonstrate that this is due to spatial non-uniformities in the plasma gain that cause the Rabi oscillations to dampen dramatically. Large amplitude Rabi-like oscillations are expected to appear only in long and uniform plasma. Such targets require optimized guiding techniques

A proposal for multi-tens of GW fully coherent femtosecond soft X-ray lasers

X-ray free-electron lasers1,2 delivering up to 131013 coherent photons in femtosecond pulses are bringing about a revolution in X-ray science3?5. However, some plasma-based soft X-ray lasers6 are attractive because they spontaneously emit an even higher number of photons (131015), but these are emitted in incoherent and long (hundreds of picoseconds) pulses7 as a consequence of the amplification of stochastic incoherent self-emission. Previous experimental attempts to seed such amplifiers with coherent femtosecond soft X-rays resulted in as yet unexplained weak amplification of the seed and strong amplification of incoherent spontaneous emission8. Using a time-dependent Maxwell?Bloch model describing the amplification of both coherent and incoherent soft X-rays in plasma, we explain the observed inefficiency and propose a new amplification scheme based on the seeding of stretched high harmonics using a transposition of chirped pulse amplification to soft X-rays. This scheme is able to deliver 531014 fully coherent soft X-ray photons in 200 fs pulses and with a peak power of 20 GW

Modelling of the double pass X-ray laser effects on its focalisation

In this paper we describe a new ray trace code. This code is a three dimensional description of beam propagation, including half cavity mirror. It is based on the integration of the ray equation and on the calculation of the intensity along the plasma. It works as a post-processor of the hydrodynamic/atomic code " EHYBRID ", which calculates the time evolution of the gain, the emissivity, the electronic density and the width of the plasma. We will present results obtained on different schemes of x-ray laser generation

Sources X et XUV intenses et brèves : Journées d'Orsay des 5 et 6 mars 1998

L'idée de ces journées est née du besoin de coordonner les efforts des équipes travaillant sur les nouvelles sources X et XUV intenses et brèves. Ces sources, qui arrivent maintenant à maturité, commencent à offrir des possibilités nouvelles d'applications pour de nombreux domaines de recherche. Il a paru nécessaire de faire le point des résultats obtenus récemment à la fois sur les sources et sur leurs applications, afin de lancer une prospective et de rechercher les moyens d'organiser cette communauté scientifique, harmoniser les programmes et rationaliser l'utilisation des moyens. Une question particulièrement importante et difficile a été révélée avec force au cours de ces journées. Il s'agit des besoins en optique multicouche, qui sont presque exclusivement satisfaits par des laboratoires de recherche qui ne peuvent consacrer qu'une part marginale de leur activité à cette production. En revanche, le marché est actuellement trop faible pour être pris en charge par les entreprises à un prix compatibles avec les moyens de la recherche publique. Le recueil des exposés présentés au cours de ces journées sera publié prochainement par l'université Paris-Su