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由于大气通道上介质对激光能量的吸收,改变了大气折射率,形成自散焦负透镜,从而产生热晕。热晕使激光发生畸变,限制了激光能量在大气中的有效传输。以准直高斯光束为例,模拟单脉冲和序列脉冲激光大气传输,对均匀风场和无风两种情况下激光在不同靶程光束截面的光强分布进行了数值分析。结果表明:长脉冲比短脉冲受到非线性热晕效应影响大;序列脉冲存在一个最优化脉冲间隔,使上靶光强存在20%～30%的涨幅。最后,在没有采用自适应光学系统对畸变进行补偿的情况下,提出了采用脉冲间隔适当的序列短脉冲传输来提高激光传输能量的方法。
Due to the atmospheric channel on the laser energy absorption medium, changing the refractive index of the atmosphere, the formation of self-defocus negative lens, resulting in thermal halo. Thermal halo distortion of the laser, limiting the laser energy in the atmosphere of the effective transmission. The collimated Gaussian beam is taken as an example to simulate the single-pulse and serial pulse laser atmospheric transmission, and the numerical analysis of the light intensity distribution of laser beams in different target beam sections under uniform wind field and no wind condition is carried out. The results show that the long pulse is more affected by the nonlinear thermal halo effect than the short pulse. There is an optimal pulse interval for the sequence pulse, which makes the target light intensity increase by 20% -30%. Finally, without using the adaptive optics to compensate for the distortion, a method of increasing the laser transmission energy by using an appropriate pulse sequence of short pulse intervals is proposed.