X-ray polarization spectroscopy to study energy transport in ultra-high intensity laser produced plasmas
X-ray polarization spectroscopy to study energy transport in ultra-high intensity laser produced plasmas
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DOI：
10.1088/1742-6596/112/2/022080
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发表时间：
2008-05
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通讯作者：
H. Nishimura;Y. Inubushi;Y. Okano;S. Fujioka;T. Kai;T. Kawamura;D. Batani;A. Morace;R. Redaelli;C. Fourment;J. Santos;G. Malka;A. Boscheron;A. Casner;M. Koenig;Tatsufumi Nakamura;T. Johzaki;H. Nagatomo;K. Mima
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文献类型：
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作者：
H. Nishimura;Y. Inubushi;Y. Okano;S. Fujioka;T. Kai;T. Kawamura;D. Batani;A. Morace;R. Redaelli;C. Fourment;J. Santos;G. Malka;A. Boscheron;A. Casner;M. Koenig;Tatsufumi Nakamura;T. Johzaki;H. Nagatomo;K. Mima
研究了 X 射线偏振光谱，以直接导出在高强度激光脉冲产生的等离子体中传播的热电子的速度分布函数 (VDF)。使用来自 CEA/CESTA 的 Alise 设施的激光脉冲（~10 J in~1 ps）在约 1018 W/cm2 下进行偏振测量。对氯化三层靶材进行辐照，用X射线偏振光谱仪观察C1 Heα线。测量偏振度作为目标外涂层厚度的函数。发现薄涂层时极化为弱负值，厚涂层时极化变为正值，最后为零。这一结果与为深入了解偏振 C1 Heα 辐射的产生而开发的时间相关原子动力学代码所做的预测一致。表面的去极化归因于过高的体电子温度，而深层区域的去极化则归因于致密区域中各向同性体电子的弹性散射过程。
X-ray polarization spectroscopy was studied to derive directly the velocity distribution function (VDF) of hot electrons propagating in plasma created with a high intensity laser pulse. Polarization measurement was made at around 1018 W/cm2 using a laser pulse (~10 J in ~1 ps) from Alise facility at CEA/CESTA. Chlorinated triple-layer targets were irradiated, and C1 Heα line was observed with an x-ray polarization spectrometer. Polarization degrees were measured as a function of the target overcoat thickness. It is found that the polarization is weakly negative for thin coating, but becomes positive, and finally zero for thick coating. This result is consistent with predictions made with a time-dependent atomic kinetics code developed to gain an insight into the generation of polarized C1 Heα radiation. The de-polarization on the surface is attributed to excessive bulk electron temperature and that in the deep region to elastic-scattering processes by the isotropic bulk electrons in dense region.