X-ray scattering measurements of dissociation-induced metallization of dynamically compressed deuterium.
X-ray scattering measurements of dissociation-induced metallization of dynamically compressed deuterium.
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DOI：
10.1038/ncomms11189
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发表时间：
2016-04-15
影响因子：
16.6
通讯作者：
Glenzer SH
中科院分区：
文献类型：
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作者：
Davis P;Döppner T;Rygg JR;Fortmann C;Divol L;Pak A;Fletcher L;Becker A;Holst B;Sperling P;Redmer R;Desjarlais MP;Celliers P;Collins GW;Landen OL;Falcone RW;Glenzer SH
氢是宇宙中最简单的元素，它的相图令人惊讶地复杂。由于在行星科学、惯性约束聚变和基础物理方面的应用，它的高压性质在过去20年里一直是人们密切研究的主题。虽然复杂的静态实验已经探测到了氢在更高压力下的结构，但使用动态压缩来检查更高温度区域的研究大多局限于光学测量技术。在这里，我们介绍了动态压缩的重氢中等离子体激元的光谱分辨x射线散射测量。结合康普顿散射和速度干涉法来确定冲击压力和质量密度，这使我们能够提取作为压缩函数的电离态。电离的开始发生在接近密度泛函理论-分子动力学(DFT-MD)模拟显示分子解离的压力下，这表明氢从分子和绝缘流体转变为导电态，而不通过中间原子相。高压实验在理解行星内部方面发挥着关键作用，但众所周知，它很难进行。在这里，作者展示了一个实验室平台，用于受控地探索氚，其结果挑战了现有的压缩电离模型。
Hydrogen, the simplest element in the universe, has a surprisingly complex phase diagram. Because of applications to planetary science, inertial confinement fusion and fundamental physics, its high-pressure properties have been the subject of intense study over the past two decades. While sophisticated static experiments have probed hydrogen's structure at ever higher pressures, studies examining the higher-temperature regime using dynamic compression have mostly been limited to optical measurement techniques. Here we present spectrally resolved x-ray scattering measurements from plasmons in dynamically compressed deuterium. Combined with Compton scattering, and velocity interferometry to determine shock pressure and mass density, this allows us to extract ionization state as a function of compression. The onset of ionization occurs close in pressure to where density functional theory-molecular dynamics (DFT-MD) simulations show molecular dissociation, suggesting hydrogen transitions from a molecular and insulating fluid to a conducting state without passing through an intermediate atomic phase. High-pressure experiments play a critical role in understanding planetary interiors, but are notoriously difficult to carry out. Here, the authors demonstrate a laboratory platform for the controlled exploration of deuterium, with results that challenge existing models of ionization under compression.