Oscillatory growth behavior of multistream instabilities

Resumo

Multistream instabilities in the one-dimensional Vlasov−Poisson system are studied numerically by using plasmas with multi-humped electron distributions. The evolution of the total wave energy of the plasma oscillations excited by (numerical) noise consists of transient, growth, and nonlinear saturation stages. It is found that, in the growth stage, the total wave energy oscillates for odd number of streams, but it does not oscillate for even number of streams. It is also found that different spectral (Fourier) modes can dominate different stages of the “linear” growth and nonlinear saturation stages.