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Characterization of microturbulence in TEXT by multichannel scattering of FIR laser radiation

Thesis/Dissertation ·
OSTI ID:5476273
The spectra of low frequency density fluctuations that universally exist in ohmic tokamak plasmas are thoroughly described. Here, for the first time, the successful use of a fully calibrated multichannel scattering apparatus permits detailed studies of microturbulence by measuring the S(k/sub perpendicular/, omega) spectrum during a single discharge. New results concerning the spectrum of density fluctuations are presented. The measured K/sub theta/ frequency spectra exhibit a distinct peak at each wavenumber and a dispersion relation, omega/sub peak/ versus k/sub theta/, is observed. A linear relationship between the spectral linewidth and k/sub theta/ is also unfolded with ..delta..omega/omega/sub peak approx. = 1. Heterodyne detection techniques show the fluctuations to be propagating in the electron diamagnetic drift direction. These observations are in agreement with Langmuir probe data at the plasma edge.
Research Organization:
California Univ., Los Angeles (USA)
OSTI ID:
5476273
Country of Publication:
United States
Language:
English