非链式脉冲DF激光器放电技术研究

发布时间：2018-12-18 06:15

【摘要】：中红外波段(3~5μm)是大气传输窗口,而且许多原子和分子的吸收峰也处于这一波段,人体骨骼和肌肉对于这一波段具有选择吸收性。因此中红外波段的激光光源在军事、激光雷达、大气探测、医疗等领域具有极高的应用价值和前景。目前,非链式脉冲DF激光器是该波段可以输出能量最高的激光器,而且其相对于链式反应的连续DF激光器来说,具有结构紧凑、操作简单、反应可控、光束质量好等优势,受到国内外众多研究者的关注。本文对非链式脉冲DF激光器的放电技术进行了研究。放电技术是非链式脉冲DF激光器的核心技术,直接决定着激光器的输出能量和电光转换效率。本文对紫外预电离与自引发放电两种放电方式进行了对比研究。首先使用有限元分析法模拟了两种放电方式激光器的电极间电场分布。紫外预电离放电要求使用均匀场电极以提高注入能量、增大放电体积。计算了Chang氏电极、紧凑型Chang氏电极和Ernst电极三种均匀场电极的电场分布,在相同的设计要求下Ernst电极的电极表面电场均匀区域最大,其次是紧凑式Chang氏电极,而Chang氏电极的电极表面电场均匀区域最小。计算了自引发放电电极间电场分布,阴极表面的毛刺对放电区宏观电场均匀性基本无影响,只在微米尺度上形成一系列分立的高电场区域。粗糙阴极表面的强电场区域不仅加强了电子的电场能量,还加强了阴极金属的场致发射作用,相对于周围低电场区域有更多的电子进入放电区,从而使放电开始阶段可以形成初始放电通道。通过实验研究两种放电方式的DF激光器,对两种激光器的输出能量进行优化实验,对比分析两种放电方式的DF激光器输出能量与电光转换效率。记录紫外预电离放电非链式DF激光器的放电照片,证实了均匀的电场分布可以得到稳定的体放电,并且可以增大放电体积,同时提高注入放电区的能量。通过分析两种放电方式,发现自引发放电在增大非链式DF激光器放电体积方面更具优势。
[Abstract]:The mid-infrared band (3 ~ 5 渭 m) is an atmospheric transmission window, and the absorption peaks of many atoms and molecules are also in this band. Human bones and muscles have selective absorption for this band. Therefore, the mid-infrared laser source has a high application value and prospect in military, laser radar, atmospheric detection, medical treatment and other fields. At present, the non-chained pulsed DF laser is the laser with the highest output energy in this band. Compared with the continuous DF laser with chain reaction, it has the advantages of compact structure, simple operation, controllable reaction and good beam quality. By many researchers at home and abroad attention. The discharge technology of non-chain pulsed DF laser is studied in this paper. Discharge technology is the core technology of non-chained pulsed DF laser, which directly determines the output energy and electro-optic conversion efficiency of the laser. In this paper, two discharge modes, ultraviolet preionization and self-initiation discharge, are compared and studied. Firstly, the electric field distribution between two discharge modes is simulated by finite element method. Ultraviolet preionization discharge requires the use of uniform field electrodes to increase the injection energy and increase the discharge volume. The electric field distributions of three uniform field electrodes, Chang's electrode, compact Chang electrode and Ernst electrode, were calculated. Under the same design requirements, the uniform electric field on the surface of Ernst electrode was the largest, followed by the compact Chang's electrode. However, the uniform electric field on the surface of Chang's electrode is the smallest. The distribution of electric field between self-initiated discharge electrodes has been calculated. The burr on the cathode surface has little effect on the uniformity of the macroscopic electric field in the discharge region, and only a series of discrete high electric field regions are formed on the micron scale. The strong electric field on the rough cathode surface not only strengthens the electric field energy of the electron, but also strengthens the field emission of the cathode metal. Compared with the low electric field around the cathode, more electrons enter the discharge region. Thus the initial discharge channel can be formed at the beginning of discharge. Two kinds of DF lasers with different discharge modes are studied experimentally. The output energy of the two kinds of lasers is optimized and the output energy and electro-optic conversion efficiency of the two kinds of discharge DF lasers are compared and analyzed. By recording the discharge photographs of the ultraviolet preionization discharge non-chain DF laser, it is proved that the uniform distribution of electric field can obtain stable volume discharge, increase the discharge volume and increase the energy of the injected discharge region. Through the analysis of two discharge modes, it is found that the self-initiated discharge has more advantages in increasing the discharge volume of the non-chain DF laser.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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