Spectra of ion acoustic plasma instability
Abstract
An experimental study of ion acoustic plasma turbulence in a collisiondominated positive column is presented. Linear theory predictions, which include ion Landau damping and the effects of a dc electric field, are shown to agree with measured values of convective growth rates. At high levels of turbulence, interferometric methods are not useful for studying the wave phase characteristics. Instead, the detailed spectral density for twodimensional wave propagation, S (k,ω), is obtained by performing a twodimensional spatial Fourier transform on sampled values of the frequency sweeps of the complex crosspower spectral density. The instability is found to be essentially onedimensional, with the waves propagating along the direction of the electron drift velocity. The spectra are integrated numerically, and the energy density obtained is discussed in terms of two nonlinear models of saturated state of the instability. Time and frequencyresolved power spectra are measured by sampling techniques, and compared to the predictions of linear theory. Temporal evolution of the phase characteristics is measured by a novel diagnostic technique.
 Publication:

Physics of Fluids
 Pub Date:
 October 1977
 DOI:
 10.1063/1.861771
 Bibcode:
 1977PhFl...20.1717I
 Keywords:

 Acoustic Instability;
 Ion Acoustic Waves;
 Magnetohydrodynamic Stability;
 Plasma Spectra;
 Plasma Turbulence;
 Fourier Transformation;
 Landau Damping;
 Linear Transformations;
 Power Spectra;
 Pulse Modulation;
 Spectral Energy Distribution;
 Wave Propagation;
 Plasma Physics