Based On Gradient Doped The Repetition Frequency Flakes Laser Media Amplifier Thermal Effects Characteristic

The laser driving Inertial Fusion Energy is one of the most perspective choices for our energy's future.Since the IFE requires a high energy class, repetitive operating laser facility as its driver, the research in high energy class, repetitive operating DPSSL system is undertaken in global scale. One of the most obvious challenges in the research is the thermal management issues causes by the high energy output and repetitive operation.This dissertation discusses, through theoretical modeling and numerical simulation, a new approach aimed to enhance the special coupling of heat deposition and cooling through the gradient doping of active ions in gain medium, which could elevate the performance of thermal management of laser amplifiers. As a new approach in thermal management, the gradient doping technology will enhance the thermal performances of high energy, repetitive operating laser amplifier through redistributing the heat deposition in medium. And it will enhance the spacial coupling of heating and cooling in the front-pumped active mirror amplifier, promise a good thermal management performance in such amplifiers, while maintain its advantages in coating and pumping homogenization. The researches covered in this dissertation are as follows:1. Established the 3-dimension, time involved,metaphysics coupling theoretical model with doping concentration depended heat deposition and heat transfercoefficient. Simulated the thermal, mechanical, optical, and gain characteristics of front pumped active mirror amplifiers including temperature, stress-strain and wave-front aberration, and stress induced temperature, and gain efficiency under different parameters.2. Analyzed the impact of doping gradient distribution and medium thickness to the thermal management and thermal effects. The simulation results indicate that elevating the doping concentration gradient will enhance thermal management capacity and suppress the thermal effects. However, as elevating doping gradient and reducing the medium thickness, the intensity of ASE effect will rises and depress the gain efficiency. Therefore, during the optimazaiton of laser amplifiers based on gradient doping medium, both the loss brought by thermal effects and gain efficiency must be considered as a whole to ensure the performance of amplifiers.3. Demonstrated optimization based on 10J, 10Hz,10ns Yb:YAG demonstration system. The optimization results show that the average temperature will decrease 10.97K, while the thermal gradient will decrease from 13.69K/mm to 4.01K/mm. As a result, The wave front distortion will fall by 6.4%, and the stress induced depolarization loss will drop tby 25.74% after optimization. In the mean while, the gain coefficient will increase by 11.11%.4. Due to the availability of gradient doping medium, discussed the feasibility of gradient doping material fabricated by the multi-layer bonding technology.The simulation result shows that the multi-layer bonding medium will enhance the thermal management efficiency of laser amplifier.5. Analyzed the feasibility of thermal management base on gradient doping material in the IFE amplifier scale. Proposed the undoped material bonding method to maintain the mechanical property, while keeping the thermal management property in thermal management of gradient doping. The result indicates that the average temperature and temperature distribution will remain the same with little aberration as the caliber of the medium change, and satisfy the requirement of thermal management of IFE scale amplifier.