RII Track-4: Experiments on a High Intensity, Coherent Plasma Laser through Stimulated Raman Backscattering

激光器（受激辐射光放大）本质上是一种放大器，其工作依赖于将能量泵入称为激光介质的气体、液体或固体物质中的原子电子中。高功率（几十亿瓦）、超短（几十亿分之一秒）激光脉冲的产生对激光介质提出了严格的要求。科学家们利用先进的光学技术和可以在极端强度下工作的等离子体（电离气体）来开发高功率脉冲激光器。然而，进一步的进步需要了解放大介质内部的过程，并克服限制输出功率的技术挑战。该项目致力于通过结合特拉华州立大学和劳伦斯利弗莫尔国家实验室（LLNL）的专业知识和仪器，提高基于等离子体的超快激光器的输出功率。由美国国家科学基金会（NSF）建立的刺激竞争性研究计划（EPSCoR）提供的奖学金资助，为首席研究员（PI）和她的学生提供必要的支持，以追求涉及实验、理论和模拟的综合努力。该项目为来自特拉华州立大学的早期职业研究员和学生提供了一个独特的机会，特拉华州立大学是历史上黑人学院和大学（HBCU）的成员，他们可以在一个一流的国家设施中训练建造台式高功率等离子体激光器。技术描述EPSCoR研究奖学金的目标是在台式等离子体激光器中实现峰值功率为佩瓦/亿瓦/泽瓦的超短（20-30飞秒）脉冲。实验将使用受激拉曼后向散射（SRBS），在反向传播泵浦和种子光束的配置中，通过激发等离子体朗缪尔波来放大种子激光脉冲功率。种子激光器将从特拉华州立大学运来，实验将在劳伦斯利弗莫尔国家实验室（LLNL）使用LLNL的木星激光设备（JLF）提供的泵浦激光器进行。该项目包括种子激光器的安装，等离子体波导的开发及其特性的研究，JLF激光器泵浦的单级SRBS实验的实施，最后是两级（两个气体射流）实验。这些实验将探索粒子在细胞（PIC）模拟中预测的饱和机制，并结合理论分析、模拟和实验研究来解决基于等离子体的高功率激光器的峰值功率饱和问题。该项目为PI和她的学生提供了一个独特的机会，将家庭机构的仪器与大型国家设施的仪器相结合，以理论和模拟为指导进行实验，并反过来提供有用的反馈，以验证和帮助改进理论模型。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical DescriptionA laser (Light Amplification by Stimulated Emission of Radiation) is essentially an amplifier, whose operation depends on pumping energy into the electrons of atoms in a gas, liquid, or solid substance called the lasing medium. The production of very high-power (on the order of a few billion watts), ultra-short (a few billionth of a second) laser pulses places stringent demands on the lasing medium. Scientists have used elegant optical techniques and plasmas (ionized gas) that can operate at extreme intensities to develop high-power pulsed lasers. However, further advancement requires understanding processes within the amplifying medium and overcoming technological challenges that limit the output power. This project focuses on achieving increased output power of plasma based ultrafast lasers by combining the expertise and instrumentation available at Delaware State University with those of the Lawrence Livermore National Laboratory (LLNL). The fellowship grant from the National Science Foundation (NSF) Established Program to Stimulate Competitive Research (EPSCoR) provides the Principal Investigator (PI) and her students the support needed to pursue an integrated effort involving experiments, theory, and simulations. The project offers a unique opportunity for an early career researcher and students from Delaware State University, a member of the Historically Black Colleges and Universities (HBCU), to train at a premier national facility in building a table-top high-power plasma laser. Technical DescriptionThe goal of this EPSCoR Research Fellowship is to achieve ultrashort (20-30 femtosecond) pulses at petawatt/exawatt/zettawatt peak power in a table-top plasma-based laser. The experiments will use Stimulated Raman Backscattering (SRBS), in which amplification of a seed laser pulse power occurs via excited plasma Langmuir waves in a configuration of counter-propagating pump and seed beams. The seed laser will be shipped from Delaware State University and the experiments will be performed at the Lawrence Livermore National Laboratory (LLNL) using a pump laser available at LLNL's Jupiter Laser Facility (JLF). The project involves the installation of the seed laser, development of a plasma waveguide and studies of its characteristics, implementation of a single stage SRBS experiment pumped by a JLF laser, and finally a two stage (two gas jets) experiment. These experiments will explore the saturation mechanism predicted by the particle in cells (PIC) simulations by the PI's group and use an integrated effort that combines theoretical analysis, simulations, and experimental investigation to address the peak power saturation in plasma-based high-power lasers. The project provides a unique opportunity for the PI and her students to combine home institution's instrumentation with those available at large scale national facilities to conduct experiments that are guided by theory and simulation, and in turn provide useful feedback to validate and help improve theoretical models.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.