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Development of a Multi-Layered Liquid-Cooled Mirror
Yuling Lu and Zuhai Cheng

This paper describes a new Multi-layered liquid-cooled Si Mirror with 3 cooling channels in the form of an Archimedes screw. The ANSYS program is used to optimise the design of the mirror assuming the flow rate to be 1.61m/s and the hydrostatic pressure to be 1.5×105 Pa. Modelling is used to simulate the thermal deformation process. The results illustrate that the temperature and deformation at the surface is reduced significantly and the mirror can stabilize within 3s. It is also shown in this simulation that after stopping the laser irradiation the temperature on the mirror’s surface is reduced to 20.7°C in 5s (both the temperature of the mirror and that of the fluid are assumed to be 20°C; fast enough to meet the demands of industrial applications. Following the principles of hydrodynamics, the coefficients of forced convective heat transfer at various flow rates were calculated and the curve of the peak value of surface deformation varies as a function of the flow rate. The curve illustrates that in a fully developed turbulent region, the peak value of surface deformation decreases linearly with the flow rate. The results of the experiments of thermal deformation and the surface recovery are very close to the simulation results. The effect of hydraulic pressure is shown to be that under atmospheric pressure the multi-layered liquid-cooled Si mirror is insensitive to the hydrostatic pressure of the cooling water.