Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India.
Group for Lasers and Plasmas, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal.
Nat Commun. 2017 Jun 30;8:15970. doi: 10.1038/ncomms15970.
Turbulent magnetic fields abound in nature, pervading astrophysical, solar, terrestrial and laboratory plasmas. Understanding the ubiquity of magnetic turbulence and its role in the universe is an outstanding scientific challenge. Here, we report on the transition of magnetic turbulence from an initially electron-driven regime to one dominated by ion-magnetization in a laboratory plasma produced by an intense, table-top laser. Our observations at the magnetized ion scale of the saturated turbulent spectrum bear a striking resemblance with spacecraft measurements of the solar wind magnetic-field spectrum, including the emergence of a spectral kink. Despite originating from diverse energy injection sources (namely, electrons in the laboratory experiment and ion free-energy sources in the solar wind), the turbulent spectra exhibit remarkable parallels. This demonstrates the independence of turbulent spectral properties from the driving source of the turbulence and highlights the potential of small-scale, table-top laboratory experiments for investigating turbulence in astrophysical environments.
自然界中充满了湍动磁场，广泛存在于天体物理、太阳、地球和实验室等离子体中。理解磁湍流的普遍性及其在宇宙中的作用是一个突出的科学挑战。在这里，我们报告了在由强台式激光产生的实验室等离子体中，磁湍流从最初的电子驱动状态向离子磁化主导状态的转变。我们在饱和湍动谱的磁化离子尺度上的观测结果与航天器对太阳风磁场谱的测量结果惊人地相似，包括谱拐点的出现。尽管源自不同的能量注入源（即实验室实验中的电子和太阳风中的离子自由能源），但湍动谱表现出显著的相似性。这表明湍动谱性质与湍动的驱动源无关，并突出了小型台式实验室实验在研究天体物理环境中的湍动的潜力。
