Dependence of transient gain on gas-flow velocity and discharge current in the FAF CO/sub 2/ laser amplifier

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · IEEE (Institute of Electrical and Electronics Engineers) Journal of Quantum Electronics; (USA)

DOI:https://doi.org/10.1109/3.35233· OSTI ID:5653824

Sato, H; Tsuchida, E ^[1]

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1. Dept. of Electrical Engineering, National Defense Academy, Yokosuka 239 (JP)

It has been believed that there is no gas dissociation of a CO/sub 2/ molecule in an open-cycle fast-axial flow type (FAF) CO/sub 2/ laser system; nevertheless we have observed transient behaviors in which the output power amplified through the FAF CO/sub 2/ laser amplifier decreases temporally after initiating the discharge. The output power becomes stable within a few minutes, i.e., the transient time. These phenomena should strongly depend on input irradiance I/sub in/, plasma length l, gasflow velocity {nu} and discharge current I/sub dis/. Thus introducing the effect of both {nu} and I/sub dis/ into the gas temperature T, the gas dissociation rate 1-{delta} with the dissociation factor zeta, the pumping rate eta and the saturation factor zeta with respect to the plasma length, the small-signal gain{gamma}/sub 0/ is theoretically formulated as a function of {nu} and I/sub dis/, and the discharge time t for a partially-homogeneously-broadened, slightly-saturated gain medium at individual vibrational-rotational transitions. The small-signal gain {gamma}/sub 0/ is numerically calculated as a function of {nu} and I/sub dis/ with the formulas derived above. Using this gain the power decrease {Delta}P and the transient time t/sub st/ required to reach equilibrium are also calculated for various {nu} and I/sub dis/. Based on the mass spectroscopic verification of the CO/sub 2/ gas-dissociation in the FAF amplifier, the experimental results of the power decrease and the transient time, together with {gamma}, are compared with the theoretical estimates.

• OSTI ID: 5653824
• Journal Information: IEEE (Institute of Electrical and Electronics Engineers) Journal of Quantum Electronics; (USA), Journal Name: IEEE (Institute of Electrical and Electronics Engineers) Journal of Quantum Electronics; (USA) Vol. 25:9; ISSN 0018-9197; ISSN IEJQA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
AMPLIFICATION
AMPLIFIERS
CARBON DIOXIDE LASERS
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUID FLOW
GAIN
GAS FLOW
GAS LASERS
LASERS
OPTICAL PUMPING
PULSE AMPLIFIERS
PUMPING
TRANSIENTS