Study of Nonthermal Electron Driven Warm Dense Plasmas Using X-Ray Free Electron Lasers

利用 X 射线自由电子激光器研究非热电子驱动的暖致密等离子体

• 批准号: 2010502
• 负责人: Hiroshi Sawada
• 金额: $ 49.5万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2010502&HistoricalAwards=false
• 关键词: Study; Nonthermal; Electron; Driven; Warm

This project will explore fundamental properties of warm dense matter, a relatively low temperature but very high density plasma composed of electron and ions. In particular, the properties of so-called "non-thermal" electrons, a small but important population of high-energy electrons that are not in thermal equilibrium with the rest of the plasma, will be studied experimentally and computationally. Theoretical and numerical modeling of warm dense matter (WDM) is challenging because temperature and density ranges of WDM are too cold and dense to apply traditional plasma physics theory, but its temperature is too high to be treated with condensed matter physics techniques. In experiments, the high density and low temperature of WDM also prevent the use of conventional plasma diagnostics. To overcome these challenges, this project will use ultrashort hard x-ray pulses delivered by X-ray Free Electron Lasers (XFEL) to study the creation and characterization of nonthermal electron driven warm dense matter with a high-power short-pulse laser. The XFEL’s hard x-ray pulses penetrate through dense plasma to provide the conditions of its interior, while the ultrashort pulses enable capturing snapshots of time-evolving plasma states. Ultrafast time-resolved measurements of short-pulse laser-driven WDM could both help develop theoretical and computational models connecting condensed matter physics and plasma physics, and reveal the role of nonthermal electrons in unexplored WDM regimes relevant to astrophysical and fusion plasmas. This project will also include training of graduate and undergraduate students at state-of-the-art XFEL facilities in Japan and Germany.The goals of this project are to infer conditions of nonthermal electron driven warm dense matter with XFEL-based diagnostic techniques, and to obtain time-resolved information on heating, equilibration and cooling phases of matter. The interaction of a femtosecond relativistic intensity laser with a solid target can produce a beam of nonthermal electrons with the energies ranging between 10's of keV to several MeV. The transport of the electrons isochorically heats and transforms the solid into warm dense matter, while the density remains constant. Using ~10 fs XFEL pulses, instantaneous conditions of the heated target, specifically electron temperatures and ionization states, can be diagnosed with X-ray Thomson Scattering and x-ray transmission imaging with a ~100 fs temporal resolution. Subsequently, time histories of the plasma conditions can be constructed by varying a time delay between the XFEL and the optical laser. Experimental results will be compared with two-dimensional particle-in-cell plasma simulations and density functional theory-based quantum electron simulations. This project is jointly funded by Division of Physics and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这个项目将探索温暖致密物质的基本性质，这是一种温度相对较低但密度非常高的等离子体，由电子和离子组成。特别是，将通过实验和计算来研究所谓的“非热”电子的性质，“非热”电子是一小部分但重要的高能电子，它与等离子体的其余部分不处于热平衡状态。热致密物质(WDM)的温度和密度范围太冷和太密，不能应用传统的等离子体物理理论，而它的温度太高，不能用凝聚态物理技术来处理，因此对WDM的理论和数值模拟是具有挑战性的。在实验中，波分复用器的高密度和低温度也阻碍了常规等离子体诊断的使用。为了克服这些挑战，该项目将使用X射线自由电子激光(XFEL)提供的超短硬X射线脉冲来研究高功率短脉冲激光产生和表征非热电子驱动的热致密物质。XFEL的硬X射线脉冲穿透稠密的等离子体，提供其内部的条件，而超短脉冲能够捕捉到时间演变的等离子体状态的快照。对短脉冲激光驱动的波分复用器进行超快时间分辨测量，可以帮助建立联系凝聚态物理和等离子体物理的理论和计算模型，并揭示非热电子在与天体物理和聚变等离子体相关的未知波分复用器中的作用。该项目还将包括在日本和德国最先进的XFEL设施中对研究生和本科生进行培训。该项目的目标是利用基于XFEL的诊断技术来推断非热电子驱动的热致密物质的条件，并获得关于物质加热、平衡和冷却阶段的时间分辨信息。飞秒相对论强度激光与固体靶的相互作用可以产生能量从10‘S电子伏特到几个MeV的非热电子束。在密度保持不变的情况下，电子的传输等温地加热固体，并将其转变为温暖的致密物质。利用X射线汤姆逊散射法和X射线透射法，利用~10fs的XFEL脉冲，可以诊断加热目标的瞬时状态，特别是电子温度和电离态，时间分辨率为~100fs。随后，可以通过改变XFEL和光学激光器之间的时间延迟来构建等离子体条件的时间历史。实验结果将与二维胞内粒子等离子体模拟和基于密度泛函理论的量子电子模拟进行比较。该项目由物理部和已建立的激励竞争性研究计划(EPSCoR)共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Ultrafast time-resolved 2D imaging of laser-driven fast electron transport in solid density matter using an x-ray free electron laser

使用 X 射线自由电子激光器对固体密度物质中激光驱动的快速电子传输进行超快时间分辨二维成像

• DOI: 10.1063/5.0130953
• 发表时间: 2023
• 期刊: Review of Scientific Instruments
• 影响因子: 1.6
• 作者: Sawada, H.;Yabuuchi, T.;Higashi, N.;Iwasaki, T.;Kawasaki, K.;Maeda, Y.;Izumi, T.;Nakagawa, Y.;Shigemori, K.;Sakawa, Y.
• 通讯作者: Sakawa, Y.

2D monochromatic x-ray imaging for beam monitoring of an x-ray free electron laser and a high-power femtosecond laser

用于 X 射线自由电子激光器和高功率飞秒激光器光束监测的 2D 单色 X 射线成像

• DOI: 10.1063/5.0014329
• 发表时间: 2021
• 期刊: Review of Scientific Instruments
• 影响因子: 1.6
• 作者: Sawada, H.;Trzaska, J.;Curry, C. B.;Gauthier, M.;Fletcher, L. B.;Jiang, S.;Lee, H. J.;Galtier, E. C.;Cunningham, E.;Dyer, G.
• 通讯作者: Dyer, G.