X-ray spectroscopy of extreme states of matter created by petawatt-laser-driven nanostructured arrays

从光学激光器到近固体密度等离子体的能量直接耦合受到限制，因为在材料的临界密度之外，光的穿透深度可以忽略不计，这使得很难创建均匀、致密、高能量密度的系统。然而，通过在纳米尺度上调整材料的表面特性，特别是通过生产由定向、各向异性纳米线组成的纳米结构目标，可以开发出具有完全不同光学特性的新型样品。这种纳米线最近被证明能够增强物质与光的耦合，产生超过95%的吸收率，并且在金属样品中具有较大的穿透深度。该项目将重点研究光与这种纳米结构目标的相互作用，并将研究它们与大规模PW激光系统相互作用时的行为。这些系统有望在与天体物理和惯性约束聚变研究相关的条件下获得物质的新方法，但也显示出作为明亮激光驱动的x射线和粒子束的新来源的潜力。将采用一系列实验诊断，包括x射线发射光谱，并结合基于非lte原子动力学模拟的计算工具。该项目由牛津儿童教育促进会提供部分资金，并与AWE密切合作。该项目属于EPSRC的等离子体和激光、光物质相互作用和光学现象研究领域。

The direct coupling of energy from an optical laser to a near-solid-density plasma is limited due tonegligible penetration depths of light beyond the critical density of a material, making it difficult tocreate homogeneous, dense, high-energy-density systems. However, by tailoring the surfaceproperties of materials at the nanoscale - in particular by producing nano-structured targetscomposed of oriented, anisotropic nano-wires - novel samples can be developed with substantiallydifferent optical properties. Such nano-wires have recently been shown capable of stronglyenhancing the coupling of matter with optical light, yielding absorptions exceeding 95%, and largepenetration depths in metallic samples.This project will focus on investigating the interaction of light with such nano-structured targets, andwill study their behaviour when interacting with large-scale PW laser systems. These systemsshow promise as a new way to access matter in conditions relevant to astrophysical and inertialconfinement fusion research, but also show potential as a novel source of bright laser-driven X-rayand particle beams. A range of experimental diagnostics including X-ray emission spectroscopy willbe employed, and coupled with computational tools based on non-LTE atomic kinetics simulations.This project is part-funded by OxCHEDS and is run in close collaboration with AWE. This projectfalls within the EPSRC research areas of Plasma and lasers, and Light matter interaction andoptical phenomena.