Generation of relativistic electron mirrors and frequency upconversion in laser-plasma interactions

It is shown analytically and by computer simulation that relativistic electron mirrors (bunches with extremely short length) can be generated by an ultra-intense nonadiabatic laser pulse (pulse with a sharp rising edge) incident normally upon a thin rarefied plasma layer provided the cross dimensions of laser beam are large enough. Due to Coulomb forces, the electron mirror is a transient structure that exists as a single whole only during a limited time at the beginning of the laser-plasma interaction. Frequency upconversion of the probe laser pulse into the single, ultrashort, and coherent hard x-ray pulse due to backscattering off such a relativistic electron mirror is also considered and the spectrum of upshifted radiation is investigated. (C) 2004 American Institute of Physics.