Magnetic Field Advection in High Energy Density Plasmas Produced by Radial Foil Configurations

开发可持续的清洁能源，研究物质的简并态或理解宇宙动力学，都需要对控制极高压电离气体（也称为高能量密度等离子体）的基本机制有详细的了解。特别是高能等离子体对磁场的平流，对国际科学界来说仍然是一个悬而未决的问题。本研究计划使用径向箔结构来研究这一主题。在这个实验装置中，薄金属箔是由一个大型脉冲发电机驱动的。一个引脚阴极与箔的几何中心接触，而箔的外围与一个圆形阳极相连。汇聚的电流产生的等离子体压力接近兆巴，是地球大气压力的一百万倍。实验装置得益于准对称等离子体动力学和良好的诊断通路。这种结构允许三维重建等离子体的特性，如磁场、质量密度、速度和温度。本研究结合多个时间间隔的测量结果，分析了等离子体参数的时间演化，揭示了等离子体磁场平流的机制。这个研究项目也影响了等离子体物理的其他领域。我们计划将实验结果与数值计算进行比较，以验证先进的等离子体模型。由于等离子体理论和数值模拟可以被更大的等离子体物理界使用，这项研究将有益于等离子体研究的其他领域，如磁约束聚变。此外，该研究还研究了磁场与超音速等离子体流的相互作用，超音速等离子体流是在超新星和黑洞周围的吸积盘中普遍存在的天体物理现象。由于良好的标度定律，径向箔产生的等离子体可以通过提供详细的超音速等离子体测量来帮助解开天体物理机制。反过来，这些数据可以用来验证天体物理理论和数值代码，促进HED物理学和天体物理学社区之间的交叉授粉。

Developing sustainable clean energy sources, studying the degenerate states of matter or understanding the dynamics of the Universe require a detailed knowledge of the basic mechanisms ruling extremely high pressure ionized gases, also called high energy density (HED) plasmas. In particular, the advection of the magnetic field by HED plasmas remains an open question to the international scientific community. This research program investigates this topic using radial foil configurations. In this experimental arrangement, a thin metallic foil is driven by a large pulsed power generator. A pin cathode contacts the foil at its geometrical center while the foil periphery is connected to a circular anode. The converging electrical currents produce a plasma pressure close to a mega-bar, a million times the earth atmospheric pressure. The experimental setup benefits from quasi symmetric plasma dynamics and excellent diagnostic access. This configuration permits a three dimensional reconstruction of plasma properties such as magnetic field, mass density, velocity and temperature. By combining multiple measurements spaced in time, this research analyzes the time evolution of the plasma parameters and highlights the mechanisms ruling magnetic field advection in HED plasmas.This research program also impacts other area of plasma physics. We plan to compare experimental results to numerical computations to validate advanced plasma models. As plasma theory and numerical modeling can be used by the larger plasma physics community, this research will benefit other areas of plasma research, such as magnetic confinement fusion. Furthermore, the research investigates the interaction of the magnetic field with supersonic plasma flows, which are ubiquitous astrophysical occurrences encountered in supernovae and accretion disks surrounding black holes. Due to favorable scaling laws, plasmas generated by radial foils can help to unlock astrophysical mechanisms by providing detailed plasma measurements in supersonic regimes. In turn, this data can be used to validate astrophysical theory and numerical codes, fostering cross-pollination between the HED physics and astrophysics communities.