Fig. 1. Schematic of light-fluid-solid multi-field coupling in inner channel

Fig. 2. Schematic of evolution of intensity distribution of rotating beam with l=2

Fig. 3. Inner channel structure and optical path diagram

Fig. 4. Temperature distribution and optical path difference distribution of gas on axial section of inner channel. (a) Heat source distribution in fluid field; (b) temperature distribution of fluid field; (c) normalized intensity distribution of LG beam; (d) distribution of optical path difference caused by thermal effect of gas

Fig. 5. Thermal deformation distributions of window mirrors and reflection mirrors. Thermal deformation distributions of (a) window mirror 1 and (b) window mirror 2; thermal deformation distributions of (c) reflection mirror 1 and (d) reflection mirror 2

Fig. 6. Change of thermal deformation distribution of window mirrors and reflection mirrors with time

Fig. 7. Suppression effect of rotating beam on internal channel thermal effect. (a) Normalized intensity distribution of rotating beam when l=1; (b) distribution of optical path difference caused by thermal effect of gas when ω=1 rad·s^-1; (c)distribution of optical path difference caused by thermal effect of gas when ω=0 rad·s^-1

Fig. 8. Thermal deformation distributions of optical elements under different conditions. (a)‒(d) ω=1 rad·s^-1; (e)‒(h) ω=0 rad·s^-1

Fig. 9. Normalized light intensity distributions under different topological charges. (a) l=1; (b) l=2; (c) l=3; (d) l=4

Fig. 10. Distributions of Zernike coefficients of first 15 orders and β values under different topological charges. (a) Zernike coefficients of first 15 orders; (b) β values

Fig. 11. Distributions of Zernike coefficients of first 15 orders and β values under different rotational angular speeds. (a) Zernike coefficients of first 15 orders; (b) β values

Fig. 12. Distributions of Zernike coefficients of first 15 orders and β values under different gas absorption coefficients. (a) Zernike coefficients of first 15 orders; (b) β values