Accession Number : AD0713497

Title :   GAIN MEASUREMENTS IN A RAPID GAS DYNAMIC EXPANSION,

Corporate Author : BOEING SCIENTIFIC RESEARCH LABS SEATTLE WASH

Personal Author(s) : Hoffman,A. L. ; Mullaney,G. J. ; Holden,M. T. ; Pindroh,A. L.

Report Date : OCT 1970

Pagination or Media Count : 22

Abstract : A double expansion nozzle was used in a shock tube facility to study the population inversions achieved in a CO2 lasing gas mixture. For these experiments the double expansion nozzle, a form of gas-dynamic throttle, was a means for increasing the gain path length in the shock tube apparatus by a factor of five. Gain measurements were made for various reservoir conditions of temperature (1000 < or = T(0) < or = 2600K) and pressures after final expansion through a Mach = 4, twenty-nine element, multiple nozzle to (5 < or = p < or = 100 torr). The small signal gain is a function of the population inversion in the non-equilibrium flow and the line broadening. Measurements were made in both the collision and Doppler broadened regions. Numerical computations were made based on available relaxation rates and compared with experiment. Evaluations of the accuracy of these rates were made, and in the case of the depopulation of the lower laser state due to helium it was found that the V-T rate is faster than previously thought. Thus, gain measureements in a gas dynamic expansion can actually be used to measure relaxation rates. (Author)

Descriptors :   (*NOZZLE GAS FLOW, *GAS LASERS), (*CARBON DIOXIDE, *EXCITATION), RELAXATION TIME, AMPLIFIERS, MOLECULAR ENERGY LEVELS

Subject Categories : Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE