Appl Opt. 2023 Mar 10;62(8):2092-2099. doi: 10.1364/AO.484224.
This work investigates steady-state thermal blooming of a high-energy laser in the presence of laser-driven convection. While thermal blooming has historically been simulated with prescribed fluid velocities, the model introduced here solves for the fluid dynamics along the propagation path using a Boussinesq approximation to the incompressible Navier-Stokes equations. The resultant temperature fluctuations were coupled to refractive index fluctuations, and the beam propagation was modeled using the paraxial wave equation. Fixed-point methods were used to solve the fluid equations as well as to couple the beam propagation to the steady-state flow. The simulated results are discussed relative to recent experimental thermal blooming results [Opt. Laser Technol.146, 107568 (2022) OLTCAS0030-399210.1016/j.optlastec.2021.107568], with half-moon irradiance patterns matching for a laser wavelength at moderate absorption. Higher energy lasers were simulated within an atmospheric transmission window, with the laser irradiance exhibiting crescent profiles.
本工作研究了高能激光在激光驱动对流存在下的稳态热晕。虽然热晕历史上是通过规定的流体速度来模拟的，但这里引入的模型通过不可压缩纳维-斯托克斯方程的玻氏近似来求解沿传播路径的流体动力学。所得的温度波动与折射率波动相关联，光束传播使用傍轴波动方程进行建模。定点法用于求解流体方程，并将光束传播与稳态流动耦合。模拟结果与最近的实验热晕结果[Opt. Laser Technol.146, 107568 (2022) OLTCAS0030-399210.1016/j.optlastec.2021.107568]进行了讨论，在中等吸收的激光波长下，模拟结果与半月形辐照度模式匹配。在大气传输窗口内模拟了更高能量的激光，激光辐照度呈现出新月形轮廓。
