Topic/Type: 1.3 High intensity Laser Plasma Interaction, Oral

### QED cascades in the strong laser field

A. Fedotov1, N. Narozhny1, G. Mourou2, G. Korn3

1 Moscow Engineering Physics Institute (MEPhI)
2 Laboratoire d'Optique Appliquee, Ecole Polytechnique
3 Max Plank Institute for Quantum Optics, Garching

The talk will be focused on physics and the attempts to simulate numerically an absolutely novel regime of laser-matter interactions at the intensities of the order of $\small 10^{24}\mbox{W/cm}^2$ and higher. At this intensity level, which will become hopefully accessible with the ELI facility, the QED effects must come into play, giving rise to development of long cascades of successive events of hard photon emissions and electron-positron pair creations assisted by the laser field. This sort of cascades has many features in common with the electron-positron-hard photon component of the Extensive Atmosphere Showers (EAS) caused by the Cosmic Rays, which are well known for decades. However, an important distinction is that, in the case of the intense enough laser field, due to possibility of rapid acceleration for the charged particles forming the cascade, the QED cascades will develop inevitably even in the case of initially slow initial particles (e.g., in the course of any kind of interaction of focused laser pulses with material targets). The relevant peculiarities of acceleration by merely arbitrary inhomogeneous/non-stationary electromagnetic fields will be explained in details. As the cascade develops, the energy will be transferred continuously from the laser field and distributed among the continuously generated ultra-relativistic particles, providing an efficient mechanism for fast depletion of the laser pulse into the jets of relatively soft electrons, positrons and photons. The dominant role of this novel effect should be taken into account in all the problems related to laser-matter interactions at ultrahigh intensities, including both the discussions of the recent experimental proposals and the computer codes designed for numerical simulations.