激光聚变能源驱动器概念研究及核心技术探索

发布时间：2018-11-28 10:55

【摘要】：激光聚变能源研究是人类探索新能源的前沿领域,也是彻底摆脱能源短缺,发展安全、无碳、可持续理想能源的希望所在。由于聚变能源应用对激光驱动器高效、高重复频率的需求,基于激光二极管泵浦的高能高平均功率固体激光器受到人们的广泛关注,并成为未来商用激光聚变能源驱动器有力的候选方案之一。然而,其核心单元放大器中的放大自发辐射和热效应,以及放大系统的总体技术方案仍是提高装置能量转换效率和重复频率面临的关键挑战。因此,本论文以激光二极管端面泵浦叠片放大器结构为基础,进行了放大器的放大自发辐射效应、热效应,以及系统构型设计三个专题的研究,并对激光聚变能源驱动器进行了初步的概念探索。论文首先基于Yb离子泵浦与放大动力学理论和Cr4+:YAG饱和吸收方程,利用蒙特卡洛和光线追迹方法,建立了叠片放大器储能、热沉积和放大过程的三维数值模型,对放大器的放大自发辐射效应与控制进行了研究。接着提出了两种新颖的放大器结构—-渐变掺杂和间隔掺杂叠片放大器,并从增益介质的需求、储能特性、热沉积、能量输出等方面揭示了其对ASE效应的抑制作用。针对热效应对放大器性能的影响,论文接着开展了叠片放大器热效应及热管理技术的研究。基于热效应的理论基础和流体-固体共轭传热理论模型,在均匀散热和低温氦气冷却条件下,分别建立了叠片放大器的三维热力学有限元模型、热流固耦合有限元模型,并分别定量给出了放大器对氦气温度、换热系数、压强与速度的要求,以便激光片冷却,控制介质中的热效应。此外,还探索了90。石英转子和多层Cr4+:YAG技术对放大链路中热致双折射效应的补偿作用,获得了非常好的效果。在前两个专题研究的基础上,论文最后以聚变能源驱动器优化设计的受限条件为标准,从装置的放大器单元优化和系统构型优化着手,研究了叠片放大器的定标放大能力,并比较分析了LIFE和双脉冲、双向传输放大构型的能流特性,以及后一种构型的极限输出能力。研究表明,双脉冲、双向传输放大构型可在低通量下获得很高的提取效率,从而减少损伤和非线性效应,也放松了对预放的要求。
[Abstract]:Laser fusion energy research is not only the frontier of human exploration of new energy, but also the hope of getting rid of the energy shortage, developing safely, carbon-free and sustainable ideal energy. Due to the high efficiency and high repetition rate of laser driver in fusion energy application, high energy and average power solid-state laser pumped by laser diode has been paid more and more attention. And become the future of commercial laser fusion energy driver one of the candidates. However, the amplification of spontaneous emission and thermal effect in the core unit amplifier, as well as the overall technical scheme of the amplifier system, are still the key challenges to improve the energy conversion efficiency and repetition rate of the device. Therefore, based on the structure of laser diode end-pumped laminated amplifier, three topics of amplifying spontaneous emission effect, thermal effect and system configuration design are studied in this paper. The concept of laser fusion energy driver is explored. Firstly, based on the theory of Yb ion pumping and amplification dynamics and Cr4: YAG saturation absorption equation, the three-dimensional numerical model of energy storage, thermal deposition and amplification process of laminated amplifier is established by using Monte Carlo and ray tracing method. The amplified spontaneous emission effect and control of the amplifier are studied. Then, two novel amplifiers are proposed, which are gradually doped and spaced doped laminated amplifiers. The suppression of the ASE effect is revealed from the requirements of gain medium, energy storage characteristics, thermal deposition, energy output and so on. Aiming at the influence of thermal effect on amplifier performance, the thermal effect and thermal management technology of laminated amplifier are studied in this paper. Based on the theoretical basis of thermal effect and the theoretical model of fluid-solid conjugate heat transfer, a three-dimensional thermodynamics finite element model and a thermal-fluid-solid coupling finite element model for laminated amplifiers are established under the condition of uniform heat dissipation and low temperature helium cooling. The requirements of the amplifier for helium temperature, heat transfer coefficient, pressure and velocity are given respectively, in order to cool the laser plate and control the thermal effect in the medium. In addition, 90. 5% was explored. The effect of quartz rotor and multilayer Cr4: YAG on the compensation of thermal birefringence in amplification link is very good. On the basis of the first two topics, based on the limited conditions of the optimal design of fusion energy driver, the calibration amplification ability of the laminated amplifier is studied from the optimization of the amplifier unit and the configuration of the system. The energy flow characteristics of LIFE and double pulses, bidirectional transmission amplification configuration and the limit output capability of the latter configuration are compared and analyzed. It is shown that the double pulse and bidirectional transmission amplification configuration can obtain high extraction efficiency at low flux, thus reducing damage and nonlinear effect, and relaxing the requirement of preamplifier.
【学位授予单位】：中国工程物理研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN722

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