IRFP: Investigation of the Radiative Interaction between Plasmas and Ablating Heat Shields

国际研究奖学金项目使美国科学家和工程师能够在国外进行9至24个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Megan E. MacDonald博士与Christophe Laux博士在法国巴黎中央学院进行为期24个月的研究。任何进入行星大气层的航天器都需要热保护，以防止航天器在进入大气层时过热和烧毁。防止这种极端加热环境的一种方法是烧蚀热保护系统。作为一种将热量从航天器传输出去的方法，这种类型的热防护被设计成热裂解。这导致在热屏蔽层和大气等离子体之间有一个边界层，该边界层富含来自热屏蔽层和等离子体的物质。虽然我们知道这种边界层混合物可以通过吸收大气等离子体辐射的某些波长，在航天器的辐射加热中发挥重要作用，但很少有实验研究这些边界层种类对辐射阻挡的定量影响。目前的项目研究了边界层的组成和这些烧蚀热解物质吸收辐射的程度。这是通过等离子体火炬实验室的空气等离子体/烧蚀系统的光谱研究进行的。目前正在使用等离子体建模代码SPECAIR对系统进行并发建模，以进一步验证该代码。该项目对于再入应用具有明显的重要性，其中SPECAIR代码验证的直接结果将是将其用作烧蚀隔热板的预测设计工具。这不仅将提高欧洲最先进的烧蚀能力（这对任何未来的国际行星进入或样本返回任务都是必不可少的），而且还将增加美国的知识水平，因为麦克唐纳博士打算返回并加入美国研究界的国家实验室。

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. Megan E. MacDonald to work with Dr. Christophe Laux at Ecole Centrale Paris in Paris, France.Any spacecraft entering a planetary atmosphere requires thermal protection to prevent overheating and burn-up of the spacecraft upon entry. One method of protecting against such extreme heating environments is an ablative thermal protection system. As a method of transporting heat away from the spacecraft, this type of thermal protection is designed to pyrolyse. This results in a boundary layer between the heat shield and the atmospheric plasma which is rich with species from both the shield and the plasma. While it is known that this boundary layer mixture can play an important role in the radiative heating of the spacecraft by absorbing certain wavelengths radiated from the atmospheric plasma, few experimental efforts have been carried out to study the quantitative effects of these boundary layer species on radiative blocking.The current project studies both the composition of the boundary layer and the degree to which these ablator pyrolysis species absorb radiation. This is being carried out through spectroscopic studies of an air plasma/ablator system in a plasma torch laboratory. Concurrent modeling of the system with a plasma modeling code, SPECAIR, is being carried out to further validate this code.This project is of clear importance for reentry applications, where a direct result of the validation of the SPECAIR code will be its use as a predictive design tool for ablative heat shields. This will not only advance the state of-the-art in ablator capabilities in Europe (which will be essential to any future international planetary entry or sample-return missions) but also increase the state of the knowledge in the U.S., as Dr. MacDonald intends to return and join the U.S. research community at a national laboratory.