Abstract.  Extreme states with high energy densities and pressures exceeding 1 Mbar determine the properties of many stars and large planets. In the laboratory, such plasmas are created by shocks, high-energy lasers and intense particle beams. However, the interaction of lasers and particles with matter often creates states far from thermodynamic equilibrium as the energy is mostly absorbed by the electrons. The properties of the resulting systems therefore strongly depend on the subsequent relaxation processes. Systems with an internal energy source like burning fusion plasmas are also driven by the particles created. Therefore, a good understanding of particle transport and relaxation processes in dense matter is required for progress towards inertial fusion energy and for the description of laser-matter interactions.

The talk will review our present understanding of temperature relaxation and the energy loss of energetic particles in dense plasmas on the basis of quantum kinetic equations. The inclusion of quantum effects is essential as many systems of interest contain highly degenerate electrons. It is shown that quantum exchange contribution can change both relaxation times and stopping ranges by orders of magnitude. Moreover, collective excitations, strong electron-ion collisions, and the structure of the ionic subsystem need to be considered. It is demonstrated how these effects can be included in a systematic and consistent way. The application of the resulting theory to plasmas in inertial fusion experiments shows that the hot, burning region is easy to describe whereas the colder, but highly compressed matter around the central core requires a description valid for correlated quantum plasmas.