The Optimal Design And Experimental Study Of The Disk Laser Cooling System

The disk lasers are widely used in industry for its high efficiency, good beam quality,wide power range and relatively low operating costs. Most disk lasers use Yb:YAG crystals.However, because of their quasi-three-level system, their temperature sensitivity is high.With the temperature of Yb:YAG crystal increasing, the threshold value of the laser wouldrise, the slope efficiency would decrease, the misalignment tolerance of resonator woulddegrade and the output beam quality would be worse. The internal stress caused by theuneven distribution of the high temperature would lead to the rupture of the crystals.Therefore, the design of cooling system is critical for the development of the high powerdisk laser system.At first the structure of the cooling system is introduced. Then, the design and optimizationof the subsystems are comprehensively discussed. The effect of tube diameter on the total headloss is explored theoretically and experimentally. The results show that if the tube diameter isdoubled the head of delivery of the pump would decrease from139m to95m.According to the basic principle of the jet impingement and the theory of heat transfer,the structure of the cooling finger and heat sink is optimized by FLUENT and ANSYSWorkbench later. Based on the former structure of cooling finger, the optimized structure ofintake and outlet is designed. Because of the increase of the flow, the temperature of the diskwould decrease. The simulation results about the jet impingement show that the shorter ofthe length of the pinhole and impinging distance, the higher of the cooling efficiency. If theheat source is square, the nozzle of arithmetic distribution pinhole aperture which hasnon-uniform heat transfer coefficient would keep the temperature of the disk crystal even.Also, it is discussed that the influence of the material and thickness of the heat sink andthe arrangement of the rectangular fins on the cooling efficiency. After the usage of thematerial with a high thermal conductivity, the temperature of the disk would greatly decrease.Though the thinner heat sink would be benefit for decreasing the temperature of the disk, thedeformation of the disk would increase. The reasonable design of the fins can enhance thecooling efficiency. After the experimental and theoretical comparisons of various coolingstructure, it is obtained that the optimized design of cooling system for disk laser crystalend-cooling.