The collision effects in underdense plasma interacting with up to relativistic level intensities laser pulse are discussing.
The coherent radiation of colliding electrons in super strong fields was analyzed. The coherent part of bremsstrahlung was found out. The qualitative analytical model describing obtained results by means of electron bunching over collision phase is suggested. The application of obtained results is discussed. Partially the attosecond pulses generation due to special instability in strong laser field is found.
In continue of nonrelativistic e-i collisions investigations in rare
plasma (PRL 1999, PoP 2001,Jetp 2003, Jetp Letters 2005, ) the
production of ultra high energy electrons in wave beam direction is
estimated. The power law distribution on electron energy (p-2 at p>>mc)
is shown. The upper level of electron energy can be up to a3mc2
(a=posc/mc is a peak normalized vector potential of the laser field).
But in real experiments the nonadiabatical effects are very important.
Partially the comparison with last experiments on .Vulkan. laser system
(PRL 94, 245001, 2005) is done. It is shown that at a=15 the upper limit
could be of the order of 2 Gev, but due to nonadiabatical effects the
cut off will be at the energy order of 100 Mev (PRL, Jetp 2006 to be
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