沿Z型光传输管道轴向吹气对激光传输的影响

Influence on beam propagation through Z-shape tube of blowing non-absorbing gas in

针对在Z型管道中传输的高能量密度激光束受到的气体热效应问题,采用光波标量衍射方程计算光传输、N S方程计算管道内流场,仿真计算了以不同的速度沿管道轴向吹入对激光能量无吸收的气体时,由于气流扰动对出射光束远场光斑质量的影响。结果表明,在采用纵向吹气减小气体热效应对光束传输的影响时,应尽可能采用大气量、低流速的方案,既有利于排空管道中的杂质气体,减小气体热效应,又有利于减小管道中流场密度分布的不均匀性,从而保证出射光束的质量。

A beam-gas-interaction model was developed by combining the scalar diffraction theory with the N-S equations. With this model, the high power density beam propagating through a Z-shape tube with blowing non-absorbing gas in at different velocities was calculated and the emitting beam qualities at far field were analyzed. The results show that, the thermal effects on beam propagation will be efficiently restrained and the beam quality at receiving section at far field could be improved. Especially, the blowing process itself may bring another greater influence which caused place of peak intensity and centroid of intensity distribution to be deviated from the ideal ones, and the higher the blowing velocity is, the greater the deviations are, the bigger the spread of beam spot is. So the adoption lower blowing velocity and a large amount of gas would be a good proposal in application of blowing non-absorbing gas in.