Warm dense matter explored with shock wave experiments

近几十年来，高能密度物理取得了令人印象深刻的进展，目前正由领先的研究小组继续快速发展。推动这一发展的是在实验室条件下产生和诊断处于高能量密度的物质状态的新可能性，以及实现这种状态的观察和探测天体物理物体的新方法，以及与应用的相关性，例如航天器的反陨石保护、惯性热核合成或核动力的安全。对正在研究的靶进行极高能量输入的最新实验方法使在各种环境中产生GPA压力成为可能，从而为研究各种材料的结构和物理性质开辟了新的机会。IPCP RAS(俄罗斯)和罗斯托克大学(德国)科学家的联合项目旨在解决非理想等离子体物理的基本问题。俄方将对激波压缩强关联等离子体的光学和输运性质进行实验研究。理论建模将由德方使用现代量子统计方法(格林函数技术、响应公式、数值模拟)进行，以便计算用于表征系统光学响应的介电函数。俄罗斯方面将提供热力学参数模拟所需的专业知识。在该项目中，我们的重点是反射率和粘度。反射率将作为压力和温度的函数进行研究，以了解探头表面出现的等离子体轮廓的物理特性。应设计新的冲击波实验。稠密的惰性气体(氙气、氩气和隐爆气体)将被用作靶材。所获得的关于稠密等离子体的偏振特性的数据将被用来创建该介质的详细物理模型，同时考虑到冲击波前沿的微观过程。剪切粘度与熵密度之比的最小要求仍然是一个悬而未决的问题，将在两个项目合作伙伴的共同努力下，从实验和理论上加以解决。这些合作的实验和理论研究将使我们能够更好地理解强关联介质中的物理过程，并解决与物质结构有关的基本问题。这些研究的结果将具有重要的基础性意义，可供有关专家在开展应用工作时使用。

In recent decades, the physics of high energy density has made an impressive progress and, at present, continues to be developed rapidly by leading research groups. This development is driven both by new possibilities to generate and diagnose at laboratory conditions states of matter at and with high energy density as well as new methods to observe and probe astrophysical objects, where such states are realized, and by the relevance for applications, for instance anti-meteorite protection of spacecrafts, inertial thermonuclear synthesis or safety of nuclear power. The latest experimental methods for extremely high energy input into targets under study led to the possibility to create GPa pressure in a variety of environments, and thus open up new opportunities for studying the structure and physical properties of various materials. The joint project of scientists of the IPCP RAS (Russia) and the Rostock University (Germany) is aimed at solving fundamental problems of nonideal plasma physics. Experimental studies of optical and transport properties of shock-compressed strongly correlated plasmas will be performed by the Russian side. The theoretical modeling will be executed by the German side using modern quantum-statistical methods (Green's function techniques, response formalism, numerical simulations) in order to calculate the dielectric function for the characterisation of the sytems' optical response. The required expertise for the simulation of thermodynamic parameters will be provided by the Russian side.Within the project we focus on reflectivity and viscosity. The reflectivity will be investigated as a function of pressure and temperature in order to understand the physics of the emerging plasma profile on the probe surface. New shock wave experiments shall be designed. Dense noble gases (xenon, argon and crypton) will be used as target materials. The obtained data on polarization properties of dense plasmas will be used to create a detailed physical model of the medium taking into account microscopic processes in the shock wave front. The claim for a minimum ratio of shear viscosity to entropy density is still an unsolved problem which will be tackled experimentally and theoretically in a combined effort of both project partners.These collaborative experimental and theoretical studies will allow a better understanding of physical processes in strongly correlated media and solve fundamental problems with respect to the structure of matter. The results of these studies will be of great fundamental importance and can be used by relevant experts when performing applied work.