IRFP: High energy ion interactions in warm dense matter

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该计划的奖项提供了联合研究的机会，以及使用国外独特或互补的设施，专业知识和实验条件。该奖项将支持博士Sophia N。在法国帕莱索的理工学院，陈博士将与Julien Fuchs Lee博士一起工作。目前的高强度短脉冲激光器已经使研究暖稠密物质（WDM）的性质成为可能。 这是一个众所周知的困难研究领域，因为它位于凝聚态，稠密等离子体和核物理之间的交界处，涵盖了广泛的研究课题，包括高压物理，应用材料研究，天体物理，电子物理，惯性聚变以及许多工业应用。在这种状态下的等离子体的密度范围从固体密度高达10倍，温度从0.1到100 eV不等。这种瞬态的性质的实验室研究具有双重挑战性：首先，在产生WDM的均匀样本中存在足够长的时间以在皮秒时间尺度上进行探测是非常困难的，其次，在理论和模型方面，这种物质是部分相关和退化的，这使得数值建模成为一个巨大的挑战。 因此，这自然表明需要实验数据来衡量当前的代码。现在，随着这些采用短脉冲高功率激光器来创建WDM的新技术，它开辟了许多现在可以研究的课题。这个项目，通过实验和建模，将回答一些基本问题。首先，由于目前的停止模型是依赖于有效的电荷状态Z* 的弹丸，如何修改Z* 取决于等离子体的特性，它通过？目前的理论模型密切预测这种相互作用，在哪些条件下？其次，需要开发什么样的基础平台来研究等离子体中的离子阻止能力，以将冷阻止数据与热等离子体阻止数据联系起来？这一方案由法国的两个实验室实施，即LULI（巴黎综合理工学院激光强度利用实验室）和CELIA（波尔多大学激光强度与应用中心）。LULI拥有独特的实验能力，即其灵活的高功率，多光束激光用户设施。利用该系统，多个激光束将允许物质在固体密度下被加热到几个eV的温度（即WDM等离子体），产生高达数十MeV的宽带离子束，并提供用于诊断的短持续时间探测束。现场诊断分为两类：测量离子束特性的诊断和提供离子束通过的等离子体条件信息的诊断。利用CELIA开发的适用于模拟短脉冲激光-等离子体相互作用的PIC和QMD程序，将为实验工作提供理论基础。最重要的是，在更广泛的范围内，这种方法将有助于验证和验证目前正在美国和欧洲开发的模拟。此外，这项研究将补充和开发在X-FEL，加速器和HiPER（欧洲激光聚变项目）研究WDM的平台，所有这些最终将在国家点火设施（NIF）准备实验。

1064468 Chen The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four-month research fellowship by Dr. Sophia N. Chen to work with Dr. Julien Fuchs Lee at Ecole Polytechnique in Palaiseau, France. Current high intensity short pulse lasers have now made possible investigations into the properties of warm dense matter (WDM) regime. This is a notoriously difficult area to study since it lies at the junction between condensed matter, dense plasma and nuclear physics, which covers a wide panel of research topics including, high-pressure physics, applied material studies, astrophysics, geophysics, inertial fusion as well as many industrial applications. Plasmas in this state have density ranging from the solid density up to 10 times greater and temperature that vary from 0.1 to 100 eV. Laboratory studies of the properties of this transient state are doubly challenging: first, there is tremendous difficulty in producing homogeneous samples of WDM which exist long enough to be probed over picosecond time-scales, and second, in regards to theory and model, such matter is partially correlated and degenerate which renders numerical modeling a tremendous challenge. This therefore naturally points to the need for experimental data to benchmark current codes. Now, with these new techniques of employing short-pulse high-power lasers to create WDM, it opens up numerous topics which can now be studied. This project, through experiments and modeling, will answer some basic questions. First, since present stopping models are dependent on the effective charge state Z* of the projectile, how does the modification of Z* depend on the characteristics of the plasma that it passes through? Which current theoretical model closely predicts this interactions and over which conditions? Second, what foundational platform would need to be developed to study ion stopping power in plasmas to bridge cold stopping to hot plasma stopping data?This program is being carried out with two laboratories in France, namely LULI (Laboratoire pour l'Utilisation des Lasers Intenses at Ecole Polytechnique) and CELIA (Centre Lasers Intenses et Applications at Université de Bordeaux). LULI houses unique experimental capability available there, namely their flexible high-power, multi-beams laser user facility. With this system, the multiple laser beams will allow matter to be heated to several eV temperatures at solid density (i.e. WDM plasmas), create a broadband ion beam up to tens of MeV, and provide short duration probe beams for diagnostics. Diagnostics fielded fall into two categories: those that measure the characteristics of the ion beams and those that provide information of the plasma conditions that the ion beam had passed through. With the PIC and QMD codes which have been adapted to simulating short pulse laser-plasma interactions developed at CELIA, the experimental effort will be grounded in theory. Most importantly on a broader scale, this approach will aid in verifying and validating simulations that are currently being developed both in the US and in Europe. Also, this research will compliment and develop platforms for studying WDM at X-FELs, accelerators, and HiPER (the European laser fusion project), all of which will ultimately prepare experiments at the National Ignition Facility (NIF).