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A simplified quasi‐two‐dimensional model for gain optimization in carbon dioxide gasdynamic lasers (GDL)
Author(s) -
Bahrampour A. R.,
Farrahi R.M.,
Radjabalipour M.
Publication year - 2002
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/fld.252
Subject(s) - nozzle , laser , supersonic speed , mechanics , optics , shock (circulatory) , wedge (geometry) , physics , materials science , thermodynamics , medicine
In this paper a simplified quasi‐two‐dimensional model for small signal gain optimization in gasdynamic laser is introduced. In order to obtain a homogeneous medium with maximum optical gain in the active medium, by nozzle shape formation, the shock occurrence position is controlled and is postponed to some point behind the laser active medium. Then the method of calculus of variation is used to find the supersonic part of the nozzle of a gasdynamic laser with maximum gain in the active medium. The interesting result is that the supersonic part of such a nozzle consists of a wedge as the accelerating part of the nozzle, a smooth surface for the uniformization, and finally a channel for the relaxation of the medium. (The middle section is characterized as the geometrical locus of points whose characteristic curves are concurrent at a certain point.) It is also shown that, overlooking a minor difference in the gain, the nozzle can be chosen to be a shock free one with the ultimate optical uniformity. Copyright © 2002 John Wiley & Sons, Ltd.