Laser Excitation and Chemi-Ionization of Combustion Species
Abstract
During the tenure of the project, we have studied the ion-molecule reactions involving collisions of low energy CHO+ ions and CH4, H2, N2 and 02, etc. molecules. Several electronically excited states have been identified and the reaction rate coefficients have been measured for the strongest band(s) of the excited state molecules or radicals and the atomic lines. We have also extensively studied the Stimulated Raman scattering processes in a wide and capillary tubings and have measured the efficiency of scattered laser lines at various wavelengths in CH4 and H2 as gain media. These experiments were performed at high pressures of these gases (100 - 500 PSI) and high pump energy (1-100 mJ) of the third harmonic of the Nd:YAG laser laser. Our results indicate that the capillary tubing is slightly more efficient that the wide bore tubing and a compact Raman laser source may be built for scientific research. In addition, we have studied the competition between the stimulated Raman and Brillouin scattering processes and calculated the corresponding gain coefficients. During the studies of the scattering processes, we have observed the two photon excitation and dissociation of CH4 and H2 molecules using the third harmonic pulsed laser line at 355 run from Nd:YAG. The photodissociative excitation of CH-radicals and H-atomic lines may be used for diagnostic purposes of the unburnt methane and hydrogen gases in combustion flame.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 15, 1992
- Accession Number
- ADA260120
Entities
People
- Vikram S. Kushawaha
Organizations
- Army Research Office