Understanding the evolution of extreme states of matter driven by relativistic laser-plasma interactions is a fundamental problem in high-field physics. This is especially true for nanostructured targets, where hydrodynamic effects play a key role within the ultra-fast time scale of laser absorption. Nanowire array targets are of particular interest as they provide an efficient means to access the ultra-high-energy-density regime due to their increased optical absorption, and have been shown to act as very efficient x-ray emission sources. Here we present analysis of time-resolved x-ray emission spectroscopy from petawatt-irradiated Nickel nanowire arrays, used to characterise the conditions achieved when scaling the performance of nanowire targets to relativistic intensities. A full time evolution of the plasma conditions is extracted from the experimental data, and shows good agreement with the physical interaction picture developed by prior computational studies.

理解相对论性激光-等离子体相互作用驱动的物质极端状态的演化是高场物理学中的一个基本问题。对于纳米结构的靶尤其如此，在激光吸收的超快时间尺度内，水动力效应起着关键作用。纳米线阵列靶由于其增加的光吸收而提供了一种进入超高能量密度区域的有效手段，因而受到特别关注，并且已被证明可以作为非常有效的X射线发射源。在这里，我们介绍了从百兆瓦辐射的镍纳米线阵列进行的时间分辨X射线发射光谱分析，用于表征将纳米线目标的性能按相对论强度进行缩放时所达到的条件。