采用数值计算方法分析了较高能量密度激光在光束控制系统内所产生的热效应对远场光斑质量和能量分布的影响.激光传输由近轴波方程描述,采用像屏法和快速傅里叶变换技术求解.激光加热引起的气流扰动及气体介质密度变化采用完全的Navier-Stokes方程描述,以便考虑各种不同因素的影响.Navier-Stokes方程求解采用LU-SGS分解技术.数值计算结果表明,在典型情况下,热晕引起的附加热相位会明显增大发射激光的发散,降低目标处激光能量集中度和远场光斑质量.这一方法还可扩展应用于其他气动光学问题研究.

The thermal effects, produced by the high energy laser in a beam control system, are numerically analyzed in this paper. The effects on the laser density and beam facula quality at far field are studied in particular. The propagation of laser is described by the paraxial wave equations, solved by the phase screen technique and the FFT method. The thermal turbulence motion and the air density variation are governed by the complete Navier Stokes equations, so that the variety factors could be in consideration. The Navier Stokes equations are solved by using the LU SGS factorization technique. The numerical results show that, with the additional initial thermal phase at the emitter exit, the energy density and the quality of the laser beam at far field would be prominently degraded for the typical situations.