Gain models for source-flow chemical lasers

Journal Article · Tue Jul 01 04:00:00 EDT 1986 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.337664· OSTI ID:5628510

Batteh, J H; Smith, W

Four gain models are developed for use in analyzing source-flow chemical laser resonators. The first is a rotational nonequilibrium (RNE) model which traces the evolution of each vibrational-rotational state of the lasing molecule. The second is a less detailed model based on the assumption that each vibrational level is in rotational equilibrium (RE). In the third model, in addition to the rotational equilibrium assumption, the gain is assumed to be the same for all the vibrational transitions. The equations then become identical in form to those describing single-line (SL) lasing from a two-level system. The RE and RNE models solve the chemical kinetics equations for the gain self-consistently with the gasdynamic equations describing the flow field. In the SL model coupling between the gasdynamics and the laser kinetics is eliminated by using the gasdynamics from a simple Fabry--Perot calculation at a representative value of the threshold gain to provide the flow field conditions for the resonator calculation. A fourth gain model investigates the effect of using the gasdynamic calculation from the simpler SL model in a rotational nonequilibrium kinetics model. The objectives of the study are to determine how well the more computationally efficient RE and SL models can reproduce the predictions of the RNE model, and to determine the error introduced by decoupling the solutions to the gasdynamic and laser kinetic equations. The impact of rotational nonequilibrium phenomena on lasing performance is also assessed. Comparisons for the specific case of a HF laser indicate that both the RE and SL models predict output powers and peak-power mode widths which are in good agreement with those predicted by the RNE model over a wide range of values for the resonator gain.

• Research Organization: Science Applications International Corporation, 1503 Johnson Ferry Road, Suite 100, Marietta, Georgia 30062
• OSTI ID: 5628510
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 60:1; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
AMPLIFICATION
CHEMICAL LASERS
ELECTRONIC EQUIPMENT
ENERGY LEVELS
EQUIPMENT
EXCITED STATES
GAIN
GAS DYNAMIC LASERS
GAS LASERS
HYDROFLUORIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
LASERS
MATHEMATICAL MODELS
PERFORMANCE
POWER
RESONATORS
ROTATIONAL STATES
VIBRATIONAL STATES