Explosive absorption of laser beam of finite diameter
Abstract
Explosive absorption of an infrared laser beam such as a carbon dioxide laser beam by molecules during transitions between excited states is analyzed, assuming a quasiequilibrium distribution of molecules over levels of the absorbing mode approximately identical to the Boltzmann distribution for a harmonic oscillator with the VTrelaxation time for the nth level tau (n) over VT equals n tau (1) over VT. First, the effect of heat transfer within the laser beam of finite diameter on the dynamics of explosive absorption is evaluated on the basis of the system of two equations of kinetics for vibrational energy and the transitional temperature of molecules. The stability limit of its steady state solution for boundary conditions is determined in accordance with the theory of thermal explosion. Next, the characteristics of explosive absorption related to the finiteness of the VV exchange are determined. It was determined that the threshold of explosive absorption depends on both the laser beam diameter and the laser pulse duration.
 Publication:

USSR Rept Phys Math JPRS UPM
 Pub Date:
 March 1987
 Bibcode:
 1987RpPhM.......67O
 Keywords:

 Beams (Radiation);
 Diameters;
 Explosions;
 Laser Beams;
 Molecular Excitation;
 Radiation Absorption;
 Carbon Dioxide Lasers;
 Energy Levels;
 Infrared Radiation;
 Kinetics;
 Laser Pumping;
 Mathematical Models;
 Lasers and Masers