Numerical study on thermal deformation characteristic of water-cooled mirror with interdigitated channels

A novel water-cooled mirror with interdigitated channels is proposed for solving the problems of high flow resistance and non-uniform heat dissipation in a conventional water-cooled mirror with straight channels. The temperature field and the thermal deformation of the reflecting surface of the mirror are analyzed by fluid-solid-heat coupling simulation. A comparative analysis of the new configuration and the conventional straight channel water-cooled mirror is carried out under equal flow rate and equal pressure drop, respectively. The numerical results demonstrate that the new configuration is better on the consistency of heat transfer coefficients than the conventional one. At the same time, under the condition of equal flow rate, the peak value of the deformation on the reflecting surface is decreased by around 1/3, and the global thermal distortion within the irradiated region is only about half that of the conventional one. Besides, the flow resistance of the new configuration is so small that the flow rate is about triple that of the conventional configuration under the condition of equal pressure drop, which raises its superiority over other designs. The new flow channel structure provides a feasible solution to reduce the thermal deformation of a large size laser mirror.