Large-amplitude oscillations and chaos in a Hamiltonian plasma system with many degrees of freedom.

Taking the beam-plasma system as a reference Hamiltonian system with many degrees of freedom, the connection between the development of large amplitude oscillations and stochasticity of the system (measured through the time-dependent maximum Lyapunov exponent) is investigated. It is found that the development of self-consistent large amplitude oscillations occurs in correspondence with the onset of chaos, and is related to a well defined change of topology of the phase space of the system. It is also shown that in a (Hamiltonian) linearly stable regime the development of large amplitude oscillations can occur when weakly dissipative processes are introduced.