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Scattering of laser light by laboratory plasmas.

University of British Columbia

The scattering of laser light by laboratory plasmas has been observed. When the scattering was from a plasma formed in a θ-pinch, with scattering angle of 90° , a nearly Gaussian profile of the scattered intensity as a function of wavelengths was observed, corresponding to scattering by non-interacting electrons. When the scattering was from a plasma jet, with scattering angle of 45° from the forward direction distinct satellite peaks were observed on both sides of a narrow central peak at the laser frequency as predicted by theory, 1,2,3,4 indicating a strong collective scattering effect between the electrons and the ions. The widths of the satellite lines were greater than the values predicted by theory. The discrepancy is ascribed to spatial variations in the electron density in the volume of the observed plasma. The intensities and frequencies at-which they occur these peaks also vary with the current of the plasma jet in a manner consistent with theory. The scattered intensity of the central peak was measured approximately and it agrees with theoretical prediction. Some indication of perturbation of the plasma by the incident laser light has also been observed. 1. E.E; Salpeter, Phys. Rev. 120, 1528(1960). 2. J.A. Fejer, Can. J. Phys. 38, 1114(1960). 3. J.P, Dougherty and D.T. Farley, Pro. Roy. Soc. (London) A259, 79(1960). 4. M.N. Rosenbluth and N. Rostoker, Phys. Fluids 5., 776(1962).

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2011-08-16

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http://hdl.handle.net/2429/36688

Physics

University of British Columbia

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