10 September 1987 Far-Infrared Interferometry And Faraday Rotation For Thermal Plasmas
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Proceedings Volume 0746, Industrial Laser Interferometry; (1987) https://doi.org/10.1117/12.939779
Event: OE LASE'87 and EO Imaging Symposium, 1987, Los Angeles, CA, United States
Abstract
Interferornetric methods for determining the electron concentration Ne in thermal plasmas are reviewed. Such methods depend on measuring the contribution to the refractive index of the free electrons for a probing em wave of suitable frequency. This contribution depends on the ratio of the wave frequency f to the plasma frequency fp ∞ Ne 1/2 and in practice (f/fp) must be significantly greater than unity. For thermaill plasmis, of interest for various devices and processes, probe frequencies in the range 1011 to 1013 Hz are required, corresponding to wavelengths in the millimeter to mid infrared regions, which are accessible with CO2 laser-pumped gas lasers. The technique may be implemented using a two-path laser interferometer or, in the case of a strongly magnetized plasma, by using Faraday rotation of the plane of polarization. Experiments are detailed in which both these methods were used to measure Ne in seeded combustion plasmas in a mag-netohydrodynamic generator.
© (1987) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sidney A. Self, "Far-Infrared Interferometry And Faraday Rotation For Thermal Plasmas", Proc. SPIE 0746, Industrial Laser Interferometry, (10 September 1987); doi: 10.1117/12.939779; https://doi.org/10.1117/12.939779
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