Warm dense matter explored with shock wave experiments

近几十年来，高能量密度物理学取得了令人印象深刻的进展，目前仍在由领先的研究小组迅速发展。推动这一发展的是在实验室条件下产生和诊断具有高能量密度的物质状态的新可能性，以及观察和探测实现这种状态的天体物理物体的新方法，以及与应用相关的应用，例如航天器的反陨石保护、惯性热核合成或核电安全。最新的实验方法将极高的能量输入到所研究的目标中，使得在各种环境中产生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学的基本问题。俄罗斯方面将对激波压缩强相关等离子体的光学和输运特性进行实验研究。理论建模将由德国方面使用现代量子统计方法（格林函数技术，响应形式，数值模拟）来计算系统光学响应表征的介电函数。模拟热力学参数所需的专门知识将由俄罗斯方面提供。在这个项目中，我们关注的是反射率和粘度。反射率将作为压力和温度的函数进行研究，以便了解探针表面出现的等离子体剖面的物理特性。设计新的冲击波实验。密集的惰性气体（氙、氩和密码子）将被用作目标材料。所获得的关于致密等离子体极化特性的数据将用于创建一个详细的介质物理模型，并考虑到激波前沿的微观过程。对于最小剪切粘度与熵密度之比的要求仍然是一个未解决的问题，该问题将在两个项目合作伙伴的共同努力下进行实验和理论上的解决。这些合作的实验和理论研究将使人们更好地理解强相关介质中的物理过程，并解决有关物质结构的基本问题。这些研究的结果将具有重要的基础意义，并可为相关专家在进行应用工作时使用。

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.