Stimulated light scattering in gaseous Ar, 02, and Ar-02 mixtures

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Stimulated light scattering in gaseous Ar, 02, and Ar-02 mixtures

  • Argon
  • Light--Scattering


STIMUlATED UGHT SCAmRING IN GASEOUS AI, 0,. AND Ar.<>s MlXT\JflfS CENTRE FOR NEWFOUNDLAND STUDIES TOTAL OF 10 PAGES ONLY MAY BE XEROXED (Without Author's Permission) CHIMEt JAMES HSU 255(;·1-, STIfllJLATED LIGHT SCAmRIliG IN GASEOUS Ar-. OZ' AND Ar-OZ MIXTURES by Chilllei Jues HSII Subcnitted in partial fulfilMent of the requiretnents for the degree of Haster of Science Memorial University of Newfoundland March. 1971 @ Ch!mei. James Hsu 1973 TABLE OF CONTENTS CHAPTER I INTRODUCTION CHAPTER II EXPERIMENTAL APPARATUS AND PROCEDURE 10 A. Apparatus 10 (1) Laser Sys tern 10 (2) Fabry-Perot InterferOllleters 13 (3) Gas Cells 14 B. Experimental Procedure 14 (1) Optical Arrangement 14 (2) High Pressure Gas Saq:tle Preparation 16 (3) Determination of Frequency Shifts 17 c. Error Estimates 1B (I) Errors in Frequency Shift Measurements 18 (2) Errors in Threshold Power Deterl'lination for STRS I' CHAPTER III RESULTS AND DISCUSSION 21 A. Stimulated Thermal Rayleigh Scattering (STRS) in Ar and Ar-02 Mixtures 21 B. Discussion of STRS and the Modification to the Gray-Herman Theory 29 c. Stimulated Brillouin Scattering (SBS) in Argon and Oxygen Gases 37 (1) SBS in Argon Gas 37 (2) SBS in Oxygen Gas 41 ~ (3) Calculation of the Hypersonic Speed in 02 as a Function of Gas Density 49 ACKNOWLEDGEMENTS 51 REFERENCES 52 ABSTRACT The backscattered light from pure argon and from argon-oxygen mixtures at alllbient te~erature was investigated using a giant-pulse ruby laser. The gas samples at pressures in the range of 400 psi to 5000 psi were irradiated by light at ). 6943X. whose peak power was approximately 100 HW with ~ral pulse width of 20 ns. When the backscattered light was analyzed by .eans of a Fabry-Perot interferCll'leter. its frequency profile led to a nonlinear scattering phencmenon reseriJling stiR/lated therml Rayleigh scattering (STRS) in absorbing gases. In the course of investigation. it was found that the presen

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