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Study of density fluctuations in plasmas by small-angle CO/sub 2/ laser scattering

Journal Article · · Phys. Fluids; (United States)
OSTI ID:5456562
Small-angle CO/sub 2/ laser scattering techniques are described which provide detailed information about density fluctuations in plasmas. These techniques are nonperturbative and measure the frequencies, wave vectors, and amplitudes of the density fluctuations. The theories of the scattering and the heterodyne and homodyne detection processes are described in detail for the case of small-angle scattering. Several models are developed to describe recent experiments involving both coherent and stochastic fluctuations. The laser, detector, and physical arrangement used in the experiments are described in detail. Experimental studies of driven Bernstein waves, ion acoustic turbulence in a positive column discharge, and fluctuations in tokamaks are described to illustrate these techniques. It is demonstrated that CO/sub 2/ laser scattering is useful in studying fluctuations with wavelengths between 0.01 and 1 cm and frequencies from 1 kHz to tens of giga-Hertz in plasmas with mean densities ranging from 10/sup 10/ to 10/sup 17/ cm/sup -3/.
Research Organization:
Bell Laboratories, Murray Hill, New Jersey 07974
OSTI ID:
5456562
Journal Information:
Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 23:3; ISSN PFLDA
Country of Publication:
United States
Language:
English