72 / 2023-04-12 15:25:15

Probing multi-scale spatio-temporal electron transport of relativistic laser-plasma interactions at European XFEL

极端光下的基础物理学 > 基础物理-II

Understanding the transport dynamics of electrons with a large current density in the order of 10¹² A/cm² driven by an ultra-short relativistic laser pulse irradiating upon a solid target is of fundamental importance to a wide range of topics such as particle acceleration, isochoric heating, ionization and recombination, plasma instabilities and dynamic compression in the high energy density conditions. At present, a predictive understanding of the electron transport dynamics in the solid density plasmas comes from the numerical simulations that strongly depend on the implemented physics models. Yet, the models including collision and ionization are not well benchmarked due to the lack of experimental data and thus severely hamper the understanding of electron transport dynamics. The recent commissioning of experimental platforms equipped with both optical high power laser and X-ray free electron laser (XFEL), such as European XFEL-HED, LCLS-MEC and SACLA beamlines, provides unprecedented opportunities to probe the dynamics of solid density plasmas with simultaneous high spatial and temporal resolution. In this talk, we will present the very first experimental results to study the electron transport in the solid wires driven by the 3J/30fs/100 TW laser ReLaX performed at European XFEL-HED station. By fielding the X-ray diagnostics of small angle X-ray scattering (SAXS), X-ray phase contrast imaging (PCI) and X-ray emission spectroscopy (XES) simultaneously, we are able to investigate the following multi-scale spatio-temporal processes induced by the hot electron transport ranging from femtoseconds to hundreds of picoseconds: i) plasma expansion with density gradient at ~10 nm resolution during the pre- and intra-short-laser-pulse wire interactions indicated by the time resolved SAXS; ii) the dynamics of plasma heating, ionization and possibly recombination revealed by resonant XES  up to 10 ps; iii) plasma expansion with density gradient at ~ 1 µm resolution in hydrodynamic time scales measured by the time resolved PCI. The vast hybrid magnetohydrodynamics (MHD), particle-in-cell (PIC), as well as collisional-radiative atomic simulations will be also presented to gain a comprehensive understanding of the experimental results.