HF/DF激光传输的大气衰减特性

 大气中的水汽对DF激光主要强线的吸收相对较小，而HF激光的大多数谱线受水汽和CO₂分子等的吸收较大。利用较新的HITRAN96数据库和我国不同地区的气象资料，采用逐线积分法计算了HF/DF 激光的大气衰减情况。所选的谱线中，在合肥地区（年平均）， HF的水汽吸收系数最大值可达到10km^-1的数量级，二氧化碳吸收系数最大可达10^-4~10^-3km^-1量级，P2(8)线吸收最弱；DF激光水汽吸收系数最大值可达到10^-1km^-1,比HF低2个量级，且随高度衰减很快，10km处就到10^-5~10^-4km^-1量级，P2(8)线吸收最弱。在我国，由南向北，由夏季到冬季，水汽浓度减少，大气对HF/DF激光的吸收率也相应地递减。

Atmospheric attenuation of the HF and DF laser radiation

The atmospheric attenuation properties of the HF and DF laser transmission. The absorption of water-vapor in the atmosphere is very weak to the DF spectral lines, while those of the water-vapor and CO2 are very strong to the HF spectral lines. The atmospheric attenuations of the HF and DF spectral lines are calculated based on the latest HITRAN 96 database and the meterologic data for different districts in China. For the selected HF spectral lines, the maximum absorption coefficient of water-vapor in Hefei area is up to 10 km-1, that of CO2 is up to 10-4 or l0-3 km-1 and that of P2 (8) line is the weakest. The maximum absorption coefficient of water-vapor to DF spectral lines is 2 orders in the magnitude lower than that to HF spectral lines and attenuates drastically with the increase of the altitude. When the altitude is 10 km, the absorption coefficient drops to 10-5-10-4 km-1. The absorptivities of water-vapor to HF/DF spectral lines decrease with the decrease of the water-vapor density from south to north and from summer to winter in China.