Accession Number : ADA134181

Title :   Propagation of Sound through a Gas with an Over-Population of Excited Vibrational States.

Descriptive Note : Technical rept. 1982-1983,


Personal Author(s) : Shields,F Douglas

PDF Url : ADA134181

Report Date : 20 Oct 1983

Pagination or Media Count : 23

Abstract : Calculations have been made which predict sound amplification under certain conditions when propagated through a gas with an overpopulation of vibrationally excited states. Three metastable states have been analyzed where the vibrational temperature is varying slowly on the scale of the sound period. The first is that of a long-lived vibrational mode in a diatomic gas. Calculations were made for N2, CO, 02, and C12. The second is that of a fast v-v exchange followed by a slow v-t. Calculations were made for CD4 as an example of this situation. And the third is that of a slow v-v followed by a fast v-t. Calculations were made for a mixture of N2/C02/He as an example of this situation. Some of the difficulties in experimentally observing the gain are discussed. (Author)

Descriptors :   *Sound transmission, *Gases, *Vibration, *Metastable state, Sound, Amplification, Excitation, Relaxation, Temperature, Molecular vibration, Diatomic molecules, Sound waves, Heating, Mathematical analysis, Energy transfer, Pressure, Pumping, Nitrogen, Carbon dioxide, Oxygen, Chlorine, Carbon monoxide, Helium

Subject Categories : Acoustics
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE