SELF-COOLING OF A GAS, ABSORBING LASER
RADIATION, DUE TO THE INTENSIFICATION
OF PHOTOABSORPTION CONVECTION 
G. V. Mishakov

UDC 621.373.826

The effect of decrease in the temperature of an absorbing 
gas in a volume occupied by the beam of a continuously operated laser 
with decrease in the beam diameter has been investigated experimentally 
for the case of constant radiation power. Based on theoretical evaluations 
it has been inferred that the intensification of photoabsorption convection 
is the reason for the temperature decrease. It has been shown that 
an optimum diameter of the beam exists for which (for a given radiation 
power) the temperature of the absorbing gas attains its maximum (accordingly 
the maximum is attained by the yield of the reaction of thermal decomposition 
of the gas in the case of its pyrolysis). When the diameter is optimum 
the heat loss from the beam volume by heat conduction is equal to 
the heat loss by photoabsorption convection. It has been inferred 
that in constructing an adequate theoretical model of laser-induced 
chemical vapor deposition it is necessary to take into account the 
convection.

Institute of Problems of Laser-Information Technologies, 
Russian Academy of Sciences, Troitsk, Moscow Region, Russia; 
email: mishakov@laser.ru. 
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 75, No. 2, pp. 185-
190, March-April, 2002. Original article submitted April 17, 2001; 
revision submitted July 31, 2001.

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