الفهرس 
Chapter 1 . Literature ReviewOnly 14 pages are availabe for public view
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Abstract
CO2 molecule is one of the most thoroughly investigated molecules
because it is common in our planetary atmosphere and it is also the
principal constitute gas of CO2 laser. In this work, numerical simulations
have been used to study laser induced break-down in CO2 gas and the
interaction of a laser induced plasma. The formulations are based on an
electron cascade model previously developed by Evans and Gamal. This
model solves numerically the time-dependent Boltzmann equation
simultaneously with a set of rate equations describing the population
density of the formed excited states. It includes the possible kinds of
interactions between electrons, molecules and photons. Calculations are
carried out under the experimental conditions of Simeonsson and
Miziolek where molecular CO2 at the atmospheric pressure is irradiated
with the first four harmonics of a Nd: YAG laser that cover a wavelength
range from the near infrared to the UV (1064, 532, 355 and 266 nm) with
pulse duration varies as 8 ns for the wavelength 1064 nm and 7 ns for the
shorter three wavelengths. The experimentally determined threshold
irradiance in this measurements is found to be 2.2 1010, 1.81010,
3.01010 and 1.01010 W/cm2 in a descending manner with the laser
wavelengths respectively. Taking all these considerations into account,
calculations are carried out using a computer program written in Fortran
77 to investigate the phenomenon of laser induced breakdown in CO2 gas.