CAREER: Non-Adiabatic Effects in Dense Plasmas

这个职业奖支持探索我们所知道的宇宙中存在的一些最极端的物质状态，并且可以在实验室环境中进行探测。所有可见物质都由两部分组成：重原子核被轻得多的电子包围。慢速运动的原子核通常被认为对周围飞驰的电子反应微弱。这个前提是现代物理和化学模拟技术的基石。然而，极端的环境，比如在行星和恒星的中心，会产生非常热的致密物质。这导致快速移动的电子开始与缓慢移动的原子核强烈相互作用，挑战了之前的假设。该奖项支持一些世界上最大的激光器的实验工作，包括国家点火装置-世界上最具能量的激光器。恶劣的天体物理条件将在地球上重现，在数据匮乏的地区测量原子核动力学。基本量的测量，包括粒子扩散和声速，将用于验证最先进的量子力学模拟。该项目将通过向全球等离子体界提供教育和研究机会，帮助培养下一代科学家。教育和推广将侧重于为代表性不足的学生提供使用高性能计算技术的机会和培训。密集等离子体的模拟通常采用绝热近似，通常通过电子和离子运动的不同能量尺度来证明。假设电子会立即适应离子场，而离子则被限制在一个绝热表面。最近的方法超越了这个近似值，导致了等离子体性质预测的显著差异，缺乏实验测量防止了竞争模型之间的区别。该研究计划将采用为Omega和NIF激光设备开发的新实验平台，在热致密物质状态下进行首次扩散测量。该平台将采用菲涅耳衍射射线照相技术，这是一种新型的激光驱动x射线诊断技术，可以测量缓慢的、扩散驱动的密度梯度变化，具有特殊的空间分辨率。实验工作得到了扩散系数预测的支持，该预测使用了新的先进模拟，将电子动力学纳入复杂的量子力学框架。这些模拟将由本科生进行，并在内华达大学里诺高性能计算团队的支持下进行。主要的研究目标是明确区分具有根本不同的非绝热性方法的等离子体模型。该项目由物理系和促进竞争性研究的既定计划（EPSCoR）共同资助。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。

This CAREER award supports exploration of some of the most extreme states of matter we know to exist in the universe and can probe in a laboratory setting. All visible matter is made up of two components, heavy nuclei surrounded by much lighter electrons. The slow-moving nuclei are often assumed to respond weakly to the electrons hurtling around them. This premise is the cornerstone of modern simulation techniques in both physics and chemistry. However, extreme environments, such as in the center of planets and stars, create incredibly hot dense matter. This results in fast-moving electrons that begin to strongly interact with the slow-moving nuclei, challenging previous assumptions. This award supports experimental work at some of the world's largest lasers, including the National Ignition Facility - the world's most energetic laser. The harsh astrophysical conditions will be recreated on Earth to measure the nuclei dynamics in regimes where data is scarce. Measurements of fundamental quantities, including particle diffusion and sound speed, will be used to validate state-of-the-art quantum mechanical simulations. The project will help train the next generation of scientists by offering education and research opportunities to the global plasma community. The education and outreach will focus on providing underrepresented students access to and training in high-performance computing techniques.Simulations of dense plasmas typically employ the adiabatic approximation, usually justified through the disparate energy scales of the electron and ion motion. The electrons are assumed to instantaneously adjust to the ion fields, while the ions are confined to a single adiabatic surface. Recent approaches that go beyond this approximation have led to significant differences in the predictions of plasma properties, with a dearth of experimental measurements preventing discrimination between competing models. This research program will employ a new experimental platform, developed for the Omega and NIF laser facilities, to perform the first measurement of diffusion in the warm dense matter regime. This platform will employ Fresnel Diffractive Radiography, a novel diagnostic technique for laser-driven X-rays that measures the slow, diffusion-driven changes in density gradients with exceptional spatial resolution. The experimental work is supported by predictions of the diffusion coefficient using new advanced simulations that incorporate the electron dynamics within a complex, quantum-mechanical framework. These simulations will be conducted by undergraduate students and performed with support from the University of Nevada, Reno High-Performance Computing team. The primary research goal is to clearly discriminate between plasma models with fundamentally different approaches to non-adiabaticity. This project is jointly funded by the 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.