Equilibration and Correlations in Strongly-Coupled Plasmas

超冷中性等离子体提供了一个理想的环境，在其中研究基本过程，如建立空间相关性，相变，热传输和非平衡动力学。在超冷等离子体中，相关的时间尺度很长，存在强大的光学诊断，并且初始密度分布，能量和电离状态是准确已知和可控的。所有这些都使得研究在其他实验中难以获得的现象成为可能。这项建议围绕两个诊断，这是相对简单的，但可以应用于超冷中性等离子体，以独特的方式研究平衡和相关性。荧光成像将提供空间分辨的光散射光谱，该光谱由于离子速度而被多普勒展宽和移位。通过适当选择激发和检测几何形状，由于等离子体膨胀的离子速度将与热离子速度区分开，这在以前是不可能的，并且对于研究光电离后稍后的平衡和热输运是至关重要的。小角光散射是研究液体中空间相关性的一种成熟技术。通常，当颗粒间距为埃量级时，这是用X射线完成的。但在超冷中性等离子体中，间距为微米量级，允许使用与主离子跃迁共振的可见光，并利用巨大的共振散射截面。前向散射光的角度依赖性将提供离子的静态结构因子和空间相关性的测量。由于与快脉冲激光等离子体的联系，这一提议的影响将远远超出超冷中性等离子体领域，它还将促进大量的培训和外联工作。在研究小组工作的研究生利用赖斯的地理位置和教育理念，为科学的多样性做出了巨大贡献。本科研究人员的支持，特别是从历史上代表性不足的群体，也是一个优先事项。正在为REU学生开发一个光学暑期学校。在当地学区也有为有天赋的高中生提供研究机会。

Ultracold neutral plasmas provide an ideal environment in which to study fundamental processes such as the establishment of spatial correlations, phase transitions, heat transport, and non-equilibrium dynamics. In ultracold plasmas the relevant time scales are long, powerful optical diagnostics exist, and initial density profiles, energies, and ionization states are accurately known and controllable. All of which make it possible to study phenomena that are difficult to access in other experiments. This proposal centers around two diagnostics that are relatively straightforward but can be applied to ultracold neutral plasmas to study equilibration and correlations in unique ways. Fluorescence imaging will provide a spatially-resolved light-scattering spectrum that is Doppler broadened and shifted due to ion velocity. With proper choice of the excitation and detection geometry, ion velocity due to plasma expansion will be distinguishable from thermal ion velocity, which has not been possible before and is crucial for studying equilibration and thermal transport at later times after photoionization. Small-angle light scattering is a well established technique to study spatial correlations in liquids. Typically this is done with x-rays when the particle spacing is on the order of angstroms. But in ultracold neutral plasmas, the spacing is on the order of microns, allowing use of visible light that is resonant with the principle ion transition and takes advantage of the enormous resonant scattering cross-section. The angular dependence of forward scattered light will provide the static structure factor of the ions and a measurement of spatial correlations. This proposal will have impact well beyond the field of ultracold neutral plasmas because of the connection to fast-pulse laser plasmas, and it will also foster substantial training and outreach efforts. graduate students working in the research group leverage Rice's geographical location and educational philosophy to contribute greatly to diversity in science. Support of undergraduate researchers, especially from historically under-represented groups, is also a priority. An optics summer school at Rice for REU students is being developed. There are also research opportunities for gifted high school students in a local school district.