Experimental evidence and theoretical analysis of photoionized plasma under x-ray radiation produced by an intense laser
Experimental evidence and theoretical analysis of photoionized plasma under x-ray radiation produced by an intense laser
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DOI：
10.1063/1.2946923
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发表时间：
2008-04
期刊：
影响因子：
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通讯作者：
Feilu Wang;S. Fujioka;H. Nishimura;D. Kato;Yu-Tong Li;Gang Zhao;Jie Zhang;H. Takabe
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文献类型：
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作者：
Feilu Wang;S. Fujioka;H. Nishimura;D. Kato;Yu-Tong Li;Gang Zhao;Jie Zhang;H. Takabe
在实验室条件下，利用高强度短脉冲激光对光致电离等离子体进行了实验研究。该实验由一个充满氮气的金腔组成。六束激光聚焦在金腔的内表面，从而产生腔内温度为80 eV的近乎黑体的辐射。这种辐射主要通过光致电离来加热氮气。在90-200A波长范围内观测到了从N-V到N-Vi的L壳层发射，并编制了随时间变化的详细组态计算程序来分析实验光谱。与天体物理观测的标准分析不同，光电离的证据是从谱线比率中推断出来的。实验和模拟的线谱比较表明，辐射加热的氮气达到20-30 eV的温度，远远低于源辐射温度。矛盾的是，它还表明，当辐射和等离子体温度都等于约60 eV时，也可以通过计算重现类似的谱线发射。这一误导性的结果表明，为了避免对天体物理光谱的误解，实验室中的实验模拟有时是必要的。(C)2008年美国物理研究所。
Photoionized plasma was studied experimentally under laboratory conditions by means of high intensity short pulse lasers. The experiment consists of a gold cavity filled with nitrogen gas. Six laser beams were focused on the inner surface of the gold cavity, thereby generating an almost black-body radiation having temperature of 80 eV inside the cavity. This radiation heats the nitrogen gas mainly by means of photoionization. L-shell emissions from N V to N VII have been observed in the wavelength range between 90 and 200 A. A time-dependent Detailed Configuration Accounting computer program has been developed to analyze the experimental spectra. In contrast to standard analysis of astrophysical observations, the evidence for photoionization is inferred from the spectral lines ratios. Comparison between the experimental and simulated line spectra indicates that the radiation heated nitrogen attains temperature of 20-30 eV, much lower than the source radiation temperature. Paradoxically, it is also shown that similar line emissions can be reproduced computationally also when the radiation and plasma temperatures both equal approximately 60 eV. This misleading result indicates that experimental simulation in laboratory is sometimes necessary to avoid misinterpretation of astrophysical spectra. (C) 2008 American Institute of Physics.