arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2209.02565physics.plasm-ph
收藏

laser驱动等离子体中韦伯不稳定性产生的电磁场结构的观测

Observation of electromagnetic filamentary structures produced by the Weibel instability in laser-driven plasmas

G. D. Sutcliffe, P. J. Adrian, J. A. Pearcy, T. M. Johnson, J. Kunimune, B. Pollock, J. D. Moody, N. F. Loureiro, C. K. Li

摘要:

本文介绍了用中等强度的$\sim 2 \times 10^{14}$ W/cm $^2$,$\sim1$ ns激光产生的膨胀高能量密度(HED)等离子体中电子尺度结构的实验观察。观察到的结构具有与电子驱动的韦伯不稳定性一致的波长($\sim 150-220 μm$)和生长速率($\sim 0.4-1.0$ ns $^{-1}$),其中电子分布的各向异性小,即$A\sim 0.002$。这种不稳定性被认为是一个更好的匹配所观察到的现象比其他典型的场产生机制中发现的HED等离子体,包括逆流离子韦伯和磁热不稳定性。这些观察实验表明,第一次,电子韦伯不稳定性必须被认为是与其他磁场的产生和放大机制,在扩大烧蚀等离子体,这是无处不在的HED研究。它们还提供了物理学的洞察力,在大规模天体物理等离子体中产生磁场。此外,磁功率谱的检查表明,在低于电子拉莫尔半径的尺度上,可能与分析陀螺动力学预测$|B_k|^2\propto k^{-16/3}$匹配。

英文摘要:

We present experimental observations of electron-scale structures in an expanding high-energy-density (HED) plasma generated with a modest intensity $\sim 2 \times 10^{14}$ W/cm$^2$, $\sim1$ ns laser. The observed structures have wavelengths ($\sim 150-220 μm$) and growth rates ($\sim 0.4-1.0$ ns$^{-1}$) consistent with an electron-driven Weibel instability where the anisotropy in the electron distribution is small, $A\sim 0.002$. This instability is found to be a better match to the observed phenomena than other typical field-generation mechanisms found in HED plasmas, including counter-streaming ion Weibel and magnetothermal instabilities. These observations experimentally demonstrate for the first time that the electron Weibel instability must be considered alongside other magnetic field generation and amplification mechanisms in expanding ablation plasmas, which are ubiquitous in HED research. They also provide physics insight into the generation of magnetic fields in large-scale astrophysical plasmas. Additionally, inspection of the magnetic power spectrum shows a possible scaling match to analytic gyrokinetic predictions, $|B_k|^2\propto k^{-16/3}$, at scales below the electron Larmor radius.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑