STUDIES OF LOW DENSITY PLASMAS WITH GAS LASERS.
Interim rept. 1 Jul 66-1 Jul 69,
ILLINOIS UNIV URBANA GASEOUS ELECTRONICS LAB
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The report describes many of the uses of the gas laser to study the refractive index of a plasma. It is shown that the sensitivity of the laser interferometer can be greatly enhanced by utilizing the transverse modes of an external spherical cavity. The parameters that determine the sensitivity of a spherical laser interferometer are discussed, and detailed theory of such is given. The plasma to be studied can be located in the external cavity or inside the laser cavity. The latter geometry preserves the excellent spatial resolution of the laser and also the high sensitivity of the spherical geometry. In order to achieve even higher sensitivity to very small changes in plasma refractivity, the laser heterodyne system was evolved. This was applied at the three common HeNe laser wavelengths of 0.6328 microns, 1.15 microns, and 3.39 microns. The latter transition is especially attractive because of its high gain and inherent sensitivity to the presence of the free electrons in a plasma. However, mode pulling effects at 3.39 microns are quite serious and a technique has been developed to evaluate it. Author
- Lasers and Masers
- Plasma Physics and Magnetohydrodynamics