非均匀湍流路径光传播数值模拟中相位屏间C_n^2的选取

Selection of C_n^2 between Phase Screens for Simulating Laser Propagation Along an Inhomogeneous Turbulent Path

针对非均匀湍流路径光传播的数值模拟,为减小相位屏间湍流强度均匀的假设所引起的模拟误差,数值分析了五种选择相位屏间折射率结构常数Cn2的可能方案。通过计算平面波和球面波的Rytov指数和Fried参数,对比五种方案得到的Rytov指数和Fried参数与理论结果的相对误差。结果表明,当相位屏间C2n选择为相位屏间湍流大气实际的折射率结构常数的路径平均值时,模拟误差最小,该选择方案为相位屏间C2n选取的最佳方案;当根据相位屏间湍流大气的Rytov指数相等的原则来设置相位屏分布时,选择相位屏间C2n为两相邻相位屏处折射率结构常数的几何平均值时,在一定的误差允许范围内,该选择方案具有可取性。

In the numerical simulation of light propagation along an inhomogeneous turbulent path, five methods for the selection of Cn^2, between phase screens are discussed, to reduce the error due to the assumption that turbulence between phase screens is homogeneous. By calculating Rytov index and Fried parameter of plane wave and spherical wave, relative errors between simulative and theoretical results of the five methods are compared. It is found that setting Cn^2, as the average refractive index structure constant of turbulence between phase screens can obtain the highest precision. And when the equivalent Rytov index-interval phase screen method is used to locate phase screens, choosing Cn^2, as the average value of refractive index structure constants at the positions of two phase screens is also feasible.