The goal of the present proposal is to coordinate the activities in the domain of laser-plasma interaction and high energy density matter between four partner laboratories and to elaborate more efficient relations between the theoretical developments,numerical simulations and experiments.The collaboration program accounts for the specific interests and the complementarily of competence of participating laboratories.The following subjects are chosen for the collaborative project.These are:1.The electron and ion acceleration by the ponderomotive force of ultra-relativistic laser pulses in dense plasma and applications of this process to the fuel ignition in targets for the inertial confinement fusion.2.Studies of effects of electron-ion collisions in a strong laser field and their effect on production of directed fluxes of high energy electrons and efficient plasma heating.3.Interaction of intense laser pulses with low density structured targets (foams and aerogels) for the intense x-ray generation and laser beam smoothing.4.Generation of intense electromagnetic pulses in the THz domain uisng the tightly focused sub-picosecond laser pulses.All subjects chosen in the project are at the front end of the contemporary research.They attract attention of leading scientific laboratories and make a part of many international high level projects.Among them there are European projects HiPER and ELI.The ponderomotive force of high intensity electromagnetic pulses was considered for many years as a promising way of acceleration of matter to high velocities.However,at non-relativistic intensities the laser energy absorption increases strongly the plasma temperature and the ablation pressure quickly dominates the radiation effects.The scientists of collaborating laboratories are participating in this work for several years and, independently each of them make some innovative proposals on how to improve the efficiency and performance of laser-particle acceleration in the relativistic regime.Such ideas that include multi-layered targets,foams,laser beam profiling and radiation cooling will be investigated jointly in the framework of the present project.The hard electron-ion collisions (at small impact parameters) that often neglected in plasma physics provide an efficient channel of electron acceleration in a strong laser field.This has been demonstrated in the recent publications of the scientists from IAP,LPI and CELIA.We are planning to extend these studies to the domain of relativistic laser intensities,to account for the quantum effects in the hard collisions and to evaluate the potential of collisions for the laser particle acceleration.The foam targets are attracting attention of researches for their capacity to enable an efficient laser energy absorption in a low density material and a high energy deposition par unit mass.The scientists from GSI, LPI and CELIA are studying foams fro their efficient laser beam smoothing. Within the framework of this project we will study the new technologies of foam fabrication and their doping with metallic nano-particles,develop theoretical and numerical models for their simulations,and study their performance in experiments.This will make an important contribution to the inertial fusion research and new,efficient X-ray sources.The intense laser pulse sources are considered in many laboratories as a means for creation of efficient and flexible sources in the THz domain,which remains actually underexplored.The scientists of IAP and CELIA developed recently a new approach for the generation of intense THz pulses by using a Cherenkov effect from laser pulses propagating with the light or higher-then-light velocities in air or other gases.This idea allows generating a short pulse in a chosen direction and easily the generation zone.This was already proved experimentally and we will persuade this work on a collaborative basis with the objective to develop an efficient and flexible THz source.