# Génération d'harmoniques d'ordres élevés sur miroir plasma

Abstract : When an intense laser beam is focused on a solid target, its surface is rapidly ionized and forms a dense plasma that reflects the incident field. For laser intensities above few $10^{15}Wcm^{-2}$, high order harmonics of the laser frequency, associated in the time domain to a train of attosecond pulses ($1as = 10-^{18}s$), can be generated upon this reflection. Because such a plasma mirror can be used with arbitrarily high laser intensities, this process should eventually lead to the production of very intense pulses in the X-ray domain.
In this thesis, we demonstrate that for laser intensities about $10^{19}Wcm^{-2}$, two mechanisms can contribute to the generation of high order harmonics: the coherent wake emission and the relativistic emission. These two mechanisms are studied both theoretically and experimentally. In particular, we show that, thanks to very different properties, the harmonics generated by these two processes can be unambiguously distinguished experimentally. We then investigate the phase properties of the harmonic, in the spectral and in the spatial domain. Finally, we illustrate how to exploit the coherence of the generation mechanisms to get information on the dynamics of the plasma electrons.
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https://tel.archives-ouvertes.fr/tel-00335261
Contributor : Cédric Thaury <>
Submitted on : Wednesday, November 5, 2008 - 11:03:17 PM
Last modification on : Thursday, November 12, 2020 - 3:30:08 PM
Long-term archiving on: : Thursday, September 23, 2010 - 5:45:58 PM

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• HAL Id : tel-00335261, version 3

### Citation

Cédric Thaury. Génération d'harmoniques d'ordres élevés sur miroir plasma. Physique [physics]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00335261v3⟩

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