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Spectroscopic Research of hot electron transport in Fast Igniter Plasmas

快点火器等离子体中热电子输运的光谱研究

基本信息

批准号：
13480136
负责人：
NISHIMURA Hiroaki
金额：
$ 8.77万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13480136/
关键词：
Laser Fusion Fast Igniter X-ray spectroscopy Fast electrons Relativistic plasmas プラズマ診断 Kα線分光

项目摘要

In laser fusion research, fast igniter scheme has shown a good progress. In this scheme, after compression of the fuel to more than a thousand times solid-density has occurred, the fuel is enforcedly heated with energetic electrons generated by a Peta-watt laser pulse. Efficient energy transfer to and deposition in the dense plasma is one of the critical issues in this scheme. A new spectroscopic method providing time-and space-resolved information has been established to provide a more quantitative understanding of the energy deposition than those provided by particle measurements. Moreover, an atomic kinetic equation solver, dedicated for analysis of partially ionized plasma, has been developed to extract plasma parameters such as temperature of ultra-high intensity laser produced plasma.X-ray spectra ranging from Kα to He-α lines of chlorine or aluminum were observed by using bi-layered plastic or metallic targets, and the dependence of the emitted line intensities on overcoat thickness was measured. The experimental results on the plastic targets were compared to an integrated analysis that attempted to simulate the observed spectrum: First, the experimental hot-electron energy distribution function was used as the initial condition to a one-dimensional (1D) Fokker-Planck transport calculation that is coupled to a 1D radiation hydrodynamic simulation. This provided the temporal evolution of temperature and density pro>les of the plasma. Second, these pro>les were given as input to an atomic kinetics code to provide temporal evolution of the spectra. Thus, the ionization-shifted Kα lines were calculated for comparison to experiments. The comparisons show a reasonable agreement with the experimental Cl Kα lines but not with those from higher ionization stages such as He-α line.

在激光核聚变研究中，快速点火方案已经取得了很好的进展。在这个方案中，在燃料压缩到超过1000倍的固体密度之后，燃料被Peta-watt激光脉冲产生的高能电子强制加热。高效率的能量转移和沉积在稠密等离子体中是该方案的关键问题之一。一种新的光谱方法，提供时间和空间分辨的信息已经建立，提供了一个更定量的了解比粒子测量所提供的能量沉积。此外，还开发了一个用于部分电离等离子体分析的原子动力学方程求解器，用于提取超高强度激光等离子体的温度等参数，并利用双层塑料靶和金属靶观测了氯和铝的Kα ~ He-α谱线，测量了谱线强度与涂层厚度的关系。塑料靶上的实验结果进行了比较，试图模拟所观察到的光谱的综合分析：首先，实验热电子能量分布函数被用作初始条件的一维（1D）福克-普朗克输运计算耦合到一维辐射流体动力学模拟。给出了等离子体温度和密度随时间的变化规律。第二，将这些谱线作为原子动力学代码的输入，以提供谱线的时间演化。因此，计算电离位移Kα线与实验进行比较。比较结果表明，这与Cl Kα线的实验结果有一定的一致性，但与He-α线等高电离级的结果则不一致。