Evolution from coherence to turbulence in plasmas

Highly monochromatic plasma waves are observed to evolve into turbulent spectra with spreads in frequencies and wavenumbers. In the weakly turbulent regime parametric decay and mode-coupling processes account for the spreading in frequency and wavenumber spectra. Certain parametric processes satisfying linear dispersion relations exhibit period doubling as a route to turbulence. In the strong turbulent regime, where E2/4πnT > (klambda /sub D/ )2, the route to turbulence proceeds via plasma-wave collapse. The turbulent spectra are a result of sharp spatial inhomogeneities (cavitons) and the interactions between waves trapped inside cavitons. The relationship between caviton collapse and the formation of phase-space granulations is described