Plasma mirrors are produced at the surface of solid targets ionized by intense femtosecond laser pulses . Due to their solid-like density, such plasmas specularly reflect these pulses. The main differences with an ordinary mirror is that the critical surface oscillates between +c and –c at each optical cycle and the coupling with the incident beam occurs within a thin layer, that can be easily tuned , at the interface between plasma and vacuum.
In the first part of this talk, we will present two experimental methods allowing for a complete determination of ultra-high-intensity laser electric fields on the whole pupil (TERMITE) and at focus (INSIGHT) [3,4]. We will see that full spatial and temporal metrology of such lasers can hardly be overemphasized to understand the XUV or particle beam properties and can give insights on the generation process itself as well.
In a second part, several examples of laser-produced sources will be presented as a clear evidence of vacuum laser acceleration of electrons to relativistic energies .
Finally, we will report briefly the first comprehensive experimental and numerical study of the laser-plasma coupling mechanisms as a function of the plasma interface steepness . Our results reveal a clear transition from a temporally-periodic Brunel mechanism to a chaotic dynamics associated to stochastic heating. By revealing the key signatures of these two distinct regimes on experimental observables, we provide an important landmark for the interpretation of future experiments.
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|Working group||Invited plenary talk|