强激光远场辐射光学材料的热效应研究

发布时间：2018-02-16 17:04

本文关键词： 强激光大气传输热晕材料温度场　出处：《西安电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：激光经过差不多六十年的快速发展,如今在社会的各个领域都能见到它的身影。特别是随着技术的革新,激光的功率越来越大,这也为激光应用开辟了新领域-激光武器。激光武器由于具有高精度、抗干扰能力强和机动性好等特点,各国都投入了大量的精力对其开展研究。本文主要围绕强激光远场辐射光学材料的温度场展开,分析了强激光在大气中传输的机理,较为详细的推导了由连续激光造成的稳态热晕效应的方程式以及由脉冲激光造成的瞬态热晕效应的方程式;分析了强激光辐射光学材料的机理以及激光束在材料中的传输特点和受到的影响,研究了激光束进入光学材料后的吸收机制并推导出了相关的热传导公式;结合实际情况分别推导了直角坐标系和圆柱坐标系下高斯型激光束辐照射光学材料的三维温度场;详细推导了短脉冲激光、长脉冲激光以及连续激光远场辐射光学材料温度场的解。本文的主要工作如下:1.介绍了强激光在大气中传输时产生热晕效应的物理机理,从激光与大气之间相互作用方程出发,阐述了连续激光受到的稳态热晕效应以及脉冲激光受到的瞬态热晕效应的特性和解析结果。并通过数值模拟分析了激光初始发射功率、激光在大气中传输的距离、激光束腰半径以及风速对稳态热晕效应的影响。对比分析了短脉冲激光和长脉冲激光受到的瞬态热晕效应的区别。2.分析了激光辐射光学材料过程中,光学材料对入射光束的反射、透射和吸收物理机制。研究了强激光与光学材料两者相互作用的物理机理,分析了本征吸收、自聚焦效应、多光子电离和电子崩、杂质缺陷以及非线性吸收过程。研究了强激光辐射光学材料时,激光束在材料中引起的热量转移过程、运用麦克斯韦方程组,推导了直角坐标系下的热传导方程,并给出了圆柱坐标系下含内热源的热传导方程式。3.从热传导方程出发,运用积分变换法,分别在直角坐标系和圆柱坐标系下,推导出强激光辐射光学材料的三维温度场函数。采用解析方法分析了光学材料SiC温度场分布,并与商业软件COMSOL的有限元数值分析结果对比。4.基于高斯光束的瞬态热晕效应,推导出长脉冲和短脉冲远场辐射光学材料温度场的解;针对有风时基模为连续高斯型激光束的稳态热晕效应,推导了连续激光远场辐射光学材料温度场的解,并详细分析了连续激光发射功率、腰斑半径、传输距离和风速对远场光学材料K9玻璃温升的影响。
[Abstract]:After nearly sixty years of rapid development, laser can be seen in every field of society, especially with the innovation of technology, the power of laser is getting bigger and bigger. This also opens up a new field for laser applications-laser weapons. Laser weapons are characterized by high accuracy, strong anti-jamming and good mobility. Many countries have devoted a great deal of effort to the research of it. This paper mainly focuses on the temperature field of optical materials irradiated by high intensity laser in the far field, and analyzes the mechanism of strong laser propagation in the atmosphere. The equation of steady state thermal halo effect caused by continuous laser and the equation of transient thermal halo effect caused by pulse laser are deduced in detail. The mechanism of intense laser radiation optical materials and the propagation characteristics of laser beams in the materials are analyzed. The absorption mechanism of laser beams entering the optical materials is studied and the relevant heat conduction formulas are derived. The three-dimensional temperature fields of Gao Si type laser beam irradiated optical materials in rectangular coordinate system and cylindrical coordinate system are derived respectively according to the actual situation, and the short pulse laser is deduced in detail. The main work of this paper is as follows: 1. This paper introduces the physical mechanism of the thermal halo effect when a strong laser propagates in the atmosphere, starting from the interaction equation between laser and atmosphere. The characteristics and analytical results of the steady state thermal halo effect of continuous laser and the transient thermal halo effect of pulse laser are described. The initial laser emission power and the distance of laser propagation in the atmosphere are analyzed by numerical simulation. The influence of laser waist radius and wind speed on the steady state thermal halo effect is analyzed. The difference between the transient thermal halo effect of short pulse laser and long pulse laser is compared. 2. The process of laser radiation optical material is analyzed. The physical mechanism of the interaction between intense laser and optical material is studied, and the intrinsic absorption, self-focusing effect, multiphoton ionization and electron avalanche are analyzed. Impurity defects and nonlinear absorption process. The heat transfer process caused by laser beam in the material is studied, and the heat conduction equation in the rectangular coordinate system is derived by using Maxwell's equations. The heat conduction equation with internal heat source in cylindrical coordinate system is given. Based on the heat conduction equation, the integral transformation method is used in the right angle coordinate system and the cylindrical coordinate system, respectively. The three-dimensional temperature field function of optical materials with intense laser radiation is derived. The temperature field distribution of optical material SiC is analyzed by analytical method, and compared with the results of finite element numerical analysis of commercial software COMSOL. 4. Based on the transient thermal halo effect of Gao Si beam, The solution of the temperature field of the long pulse and short pulse far-field radiation optical material is derived, and the solution of the temperature field of the far-field radiation optical material of continuous laser is deduced for the steady state thermal halo effect of the base mode of the continuous Gao Si laser beam in the wind-time. The effects of continuous laser power, waist radius, transmission distance and wind speed on the temperature rise of the far-field optical material K9 are analyzed in detail.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN24

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