Theoretical analysis of transient gain phenomena in a fast-axial flow type CO/sub 2/ laser amplifier

Publisher Website
Google Scholar
Abstract
A decrease of output power observed after discharging plasma tubes in a fast-axial flow CO/sub 2/ laser amplifier with a short dwell time of about 1 ms is discussed. For the 10P(18) line at 50 torr pressure, the small-signal gain goes from 1.308/m to 1.068/m within 135 s after discharging the plasma tubes, for a gas-flow velocity of 180 m/s and discharge current of 60 mA. The fraction of power decrease is about 15% for the plasma length of 80 cm and the input power of 5 W. Dependences of the observed fraction of power-down and the transient time to reach a stable power on input power and plasma length are theoretically analyzed by introducing the CO/sub 2/ dissociation factor as a function of gas-flow velocity, discharge current and plasma length, and gain saturation, resulting in good agreement between the experimental results and computation.