The characteristics of reduced-density channels in NH3-N2 gas mixtures

A CO2 laser was used to generate reduced-density channels in various gas mixtures of ammonia and nitrogen. Interferometers were used to record the changing density resulting from the NH3 absorption of the CO2 laser radiation. One method used to determine the characteristics of the channel was based on the assumption that the resulting density profile was Gaussian shaped. The second method used the Abel Integral Transformation, requiring no pre-conditions on the density profile expect that it was cylindrically symmetric. While used extensively in plasma spectroscopy, this technique is not generally well known for analyzing interferometric data. The results show that for a fixed laser energy long, shallow reduced density channels were formed in gas mixtures of low ammonia concentration and short, deep channels were formed in gas mixtures high ammonia concentration. These results qualitatively agree with an earlier experiment in which gas mixtures of nitrogen and sulfur-hexafluoride were used. Both experiments support the concept of reduced-density channel formation and lay the foundation for future studies of relativistic electron beam propagation for application in the Strategic Defense Initiative. Keywords: Reduced density channel; Fringe data; Interferogram; Zero Fringe Line; Reference mark; Channel depth; Channel width; Carbon dioxide laser; Theses. (MGM)