ИСТИНА

We present experimental and theoretical data on the interaction of relativistic femtosecond pulses with pre-pulse created dense plasma. We show that energy of fast electrons as well as conversion to gamma rays can be controlled efficiently by the proper choice of pre-pulse parameters. Experiments were made using ILC MSU TW laser (45 fs, 10 Hz, up to 1019 W/cm2). The 3D PIC code Mandor and the hydrodynamic code CHIC were used for numerical simulations. Interaction with melted gallium target is considered in the second part of the paper. Here we also achieved huge increase in the gamma yield and electron energy but applying short very intense femtosecond pre-pulse (advancing the main pulse by ~10 ns and having intensity of ~1016 W/cm2).