Signatures of target performance and mixing in titanium-doped, laser-driven target implosions
Signatures of target performance and mixing in titanium-doped, laser-driven target implosions
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DOI：
10.1063/1.872443
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发表时间：
1997-08
影响因子：
2.2
通讯作者：
B. Yaakobi;F. Marshall;D. Bradley;J. Delettrez;R. Craxton;R. Epstein
中科院分区：
文献类型：
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作者：
B. Yaakobi;F. Marshall;D. Bradley;J. Delettrez;R. Craxton;R. Epstein
利用嵌入钛层的吸收光谱测量了球壳的激光内爆。观察到钛层形成的预测吸收特征：由于不完全L壳层的钛离子的1 s-2 p跃迁的吸收线，以及冷钛的K边吸收。还观察到的振荡，由于EXAFS（扩展X射线吸收精细结构）以上的Ti K边缘。核心温度和壳面密度和温度来自于测量，并发现不符合一维代码模拟预测的值。这种不足是由于缺乏辐射对称性，这导致流体动力学不稳定性和混合（在本实验中没有使用相板平滑）。混合的特征包括由于钛迁移到核心而发射的Ti+20的He-α线，以及EXAFS光谱表明冷钛接近峰值压缩。
Absorption-spectroscopy measurements using an embedded titanium layer have been performed on laser implosions of spherical shells. Predicted absorption features formed by the titanium layer were observed: absorption lines due to 1s–2p transitions in titanium ions of incomplete L shell, as well as K-edge absorption in cold titanium. Also observed were oscillations due to EXAFS (Extended X-Ray Absorption Fine Structure) above the Ti K edge. The core temperature and shell areal density and temperature are derived from the measurements and are found to fall short of the values predicted by one-dimensional code simulations. This shortfall is attributed to the lack of irradiation symmetry, which leads to hydrodynamic instability and mixing (smoothing by phase plates was not used in this experiment). Signatures of mixing include the emission of the He-α line of Ti+20 due to titanium migrating to the core, as well as the EXAFS spectrum indicating cold titanium close to peak compression.