Dynamical Evolution of a Relativistic Intense Electron Beam in an Over-Dense Plasma

Summary form only given. We want to investigate the evolution of an intense relativistic electron beam when it is transported in an over-dense plasma. It is generally admitted that under these conditions, the beam goes progressively to a Bennett profile and a Maxwellian distribution for the velocities. But the problem is the understanding of the routes (stable or unstable) the beam follows and the convergence rate of the process. We explore different initial situations using diagnostics taken from the chaos mechanics (Poincare plots of section windowed as a function of time, tests of ergodicity and mixing). Finally, we propose some ideas about the evolution of the beam internal structure and the mechanisms which drive this transformation.