空气呼吸模式CO2激光等离子体光谱观察

为了了解采用脉冲CO₂激光推进空气呼吸模式时光船参数等对产生等离子体的影响，介绍了利用实验室自行研制的紫外预电离TEA CO₂激光器进行的激光等离子体实验。实验采用底面直径为60mm、焦距为5mm和10mm的抛物面光船。介绍了空气呼吸模式激光等离子体的谱和明显的特征谱线，以及等离子体的时间演化过程。结果表明：空气呼吸模式等离子体的持续时间约为20μs，在6μs左右时信号强度达到最大值；激光脉冲作用后，信号迅速衰减；10mm光船产生的等离子体信号峰值和持续时间均略长于5mm光船的。

Observation of breakdown induced by CO2 laser with air-breathing mode

In order to study the influence of flight parameters on laser-induced plasma when the pulse CO2laser is used for the air-breathing mode,the experiment of laser-induced plasma using the UV-preionized TEA CO2,laser made in our laboratory is discussed. A cylinder with a parabolic inner surface was used in this experiment,whose aperture diameter was 60 mm,and the focal lengths were 5 mm and 10 mm. The spectrum of laser-induced plasma,the distribution of characteristic lines,and the temporal behaviors of plasma in air-breathing mode were introduced in detail. The results show that the evolution of laser-induced plasma with airbreathing mode may last 20 μs,and the signal intensity reaches maximum at 6 μs. When the laser pulse has a complete effect,the signal begins to decay rapidly. In addition,the signal peak value and the persistence time of laser plasma produced by 10 mm parabolic inner surface are higher and longer than those by the short focal length flight.