By analyzing aerodynamic field in the DF chemical laser cavity, a nonuniform flowing gain model was built, including distributions of small signal gain coefficient and fluctuation of refractive index. And the effect on eigenmode characteristics of nonuniform gain was explored. The eigenmode of the loaded DF chemical laser with nonuniform gain was calculated by using the multiple gain segments method and Fox Li iterative method. A further comparison of the eigenmode phases between the bare resonator and loaded resonator was made with the power spectral density (PSD) and the Zernike aberration coefficients. The results indicate that the nonuniform flowing gain of the medium in the cavity increases the nonuniformity of the eigenmode distributions and the proportion of high frequency in wavefront phase, further leading to obvious degradation of the beam quality of the output laser beams.
