Small scale processes and macroscopic effects in collisionless plasmas

In high temperature space and laboratory plasmas, energy, initially injected at large scales, is transferred towards small scales. In a number of cases these plasmas can be considered as almost collisionless and dissipative effects become important at length scales much smaller than those where kinetic effects come into play. Here we discuss the role of microscopic small scale kinetic effects and their possible feedback on the large scale dynamics by considering two problems that exhibit interesting analogies: the nonlinear Landau damping of an electrostatic wave and the nonlinear evolution of collisionless magnetic reconnection.