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Proceedings Paper

Lasers As A Tool For Plasma Diagnostics
Author(s): Franz C. Jahoda
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Paper Abstract

Lasers can be used as non-perturbative probes to measure many plasma parameters. Plasma refractivity is primarily a function of electron density, and interferometric measurements of phase changes with either pulsed or CW lasers can determine this parameter with spatial or temporal resolution over several orders of magnitude sensitivity by using laser wavelengths from the near UV to the far infrared. Sub-categories include density gradient and/or turbulence determinations from the laser beam deflection and magnetic field magnitudes from polarization rotation by birefringence. Laser scattering from free electrons yields the most fundamental electron temperature measurements in the plasma parameter range where individual scattering events are uncorrelated in phase and ion temperature or plasma wave and turbulence structure in the opposite limit. The smallness of the scattering cross section generally limits these experiments to single points in space and time using powerful Q-switched lasers. Extensions in both spatial and temporal domains are current research topics. Laser scattering from bound electrons can be many orders of magnitude larger if the laser is matched to appropriate resonance frequencies and can be used in specialized circumstances for measuring low-ionized impurity or dominant species neutral concentrations and velocities. The mini-course will emphasize the fundamental physics underlying the many techniques and draw on particular applications examples based largely on the author's experience in magnetic confinement fusion research.

Paper Details

Date Published: 30 December 1981
PDF: 16 pages
Proc. SPIE 0288, Los Alamos Conf on Optics '81, (30 December 1981); doi: 10.1117/12.932094
Show Author Affiliations
Franz C. Jahoda, Los Alamos National Laboratory (United States)

Published in SPIE Proceedings Vol. 0288:
Los Alamos Conf on Optics '81
Donald H. Liebenberg, Editor(s)

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