High energy electrons, nuclear phenomena and heating in petawatt laser-solid experiments

The Petawatt laser at Lawrence Livermore National Laboratory (LLNL) has ope ned a new regime of laser matter interactions in which the quiver motion of plasma electrons is fully relativistic with energies extending well above the threshold for nuclear processes. In addition to similar to few MeV pond eromotive electrons produced in ultra intense laser-solid interactions, we have found a high energy component of electrons extending to similar to 100 MeV apparently from relativistic selffocusing and plasma acceleration in t he underdense preformed plasma. The generation of hard bremsstrahlung, phot onuclear reactions, and preliminary evidence for positron-electron pair pro duction will be discussed.