毛细管放电69.8nm激光强度空间分布特性研究

发布时间：2018-01-13 22:10

本文关键词：毛细管放电69.8nm激光强度空间分布特性研究　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：X射线激光是一种短波长激光,它的显著优点是脉冲短、亮度高、相干性好、频率范围窄。X射线激光在X射线成像,激光等离子体诊断,材料科学等领域应用广泛。实现X射线激光输出的方案有多种,其中,毛细管放电泵浦方案为X射线激光的小型化、实用化开辟了一片新领域。目前,采用毛细管放电泵浦方案已经实现了类氖氩46.9nm和69.8nm,类氖硫60.8nm,类氖氯52.9nm一共四个波长的软X射线激光输出。对于类氖氩46.9nm软X射线激光的研究技术比较成熟,但是国际上对于增益介质同为氩的8价离子的类氖氩69.8nm激光的报道却相对较少。本论文在理论和实验方面对类氖氩69.8nm激光强度的空间分布特性进行了研究。理论上分别针对在轴心处有轻微凹陷的电子密度分布和抛物线电子密度分布的情况,首先利用几何光学近似的方法研究了69.8nm软X射线激光在圆柱形等离子体柱中的传播轨迹,之后结合光线在等离子体柱中的增益情况计算了从等离子体柱端面和侧面出射光线的光强空间分布。此外,通过改变影响激光光强空间分布的等离子体参数如电子密度,等离子体柱半径,等离子体柱长度等,研究了不同等离子体状态下激光的光强空间分布变化规律。实验上通过改变影响激光输出的放电条件如电流,初始气压,毛细管长度研究了不同条件下69.8nm激光的光强空间分布特性。对比理论计算,分析了实验上得到的不同放电条件下光强空间分布曲线所对应的等离子体状态参数如电子密度,等离子体柱半径等的分布情况。对毛细管放电软X射线激光强度空间分布特性的研究有利于判断激光输出时的等离子体各项物理参数的分布特性,对于实现软X射线激光的增益放大,改善光束质量具有很好的指导意义。
[Abstract]:X-ray laser is a kind of short wavelength laser, which has the advantages of short pulse, high brightness, good coherence, narrow frequency range in X-ray imaging, laser plasma diagnosis. Materials science and other fields are widely used. There are many ways to realize X-ray laser output. Among them, capillary discharge pump scheme opens up a new field for the miniaturization of X-ray laser. Ne-like argon 46.9 nm and 69.8 nm, neon-like sulfur 60.8 nm have been realized by capillary discharge pumping scheme. Ne-like chlorine (52.9 nm) soft X-ray laser with four wavelengths is produced. The research technology of Ne-like argon 46.9 nm soft X-ray laser is relatively mature. However, there have been relatively few reports on Ne-like argon 69.8 nm laser with the same gain medium as argon in the world. The spatial distribution of Ne-like argon 69.8 nm laser intensity in theory and experiment has been studied in this paper. In theory, the electron density distribution and parabola electron density distribution with slight indentation at the axis are studied. Firstly, the propagation trajectory of a 69.8 nm soft X-ray laser in a cylindrical plasma column is studied by means of geometric optical approximation. Then the spatial distribution of the light intensity from the end and side of the plasma column is calculated according to the gain of the beam in the plasma column. The plasma parameters such as electron density, plasma column radius, plasma column length and so on, which affect the spatial distribution of laser intensity, are changed. The spatial distribution of laser intensity in different plasma states is studied experimentally by changing the discharge conditions such as current and initial pressure which affect the laser output. The spatial distribution of light intensity of 69.8 nm laser at different conditions has been studied by capillary length. The plasma state parameters, such as electron density, corresponding to the spatial distribution curve of light intensity under different discharge conditions are analyzed. The study on the spatial distribution of soft X-ray laser intensity in capillary discharge is helpful to judge the distribution characteristics of the plasma physical parameters in laser output. It is of great significance to realize the gain amplification of soft X-ray laser and improve the beam quality.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN241

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