Utilization of Digital Spectral Analysis Techniques in the Study of Plasma Fluctuation Data.
TEXAS UNIV AUSTIN ELECTRONICS RESEARCH CENTER
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A 7-channel, 1.5 MHz bandwidth, analog-digital data acquisition system has been developed to interface an experimental situation with a large-core-storage digital computer. This enables experimentally generated data to be used in conjunction with digitally implemented spectral analysis techniques. The purpose of this project is use these spectral analysis techniques in the study of plasma fluctuation data associated with instabilities and turbulence. This study is unique in that these spectral analysis techniques allow one to determine both the frequency omega and spatial wave-number k associated with several waves simultaneously present in the plasma. This ability to measure omega and k enables one to compute the phase velocity of each wave and thereby identify coherent oscillations buried in a noisy environment. One is also able to verify resonant frequency and wavenumber selection rules associated with nonlinear interactions of waves in the plasma. These same techniques allow one to compute the spectral indes associated with a turbulent power spectrum while simultaneously measuring k versus omega, the latter information being needed to compare theory and experimental data. This data acquisition and spectral analysis system has been used in the study of the evolution of drift-wave turbulence under various experimental conditions. Author
- Plasma Physics and Magnetohydrodynamics