随着高超声速飞行器速度的不断提高，防热材料表面和高焓非平衡来流之间的气-固耦合效应逐渐显著，机体表面气动热载荷受到严重影响，如何深入揭示气-固耦合效应作用机制已成为发展高超声速飞行器亟待解决的关键问题之一。针对上述问题，传统的以表面温度等宏观参数为指导、将材料催化特性视为常数以弱化长时气动加热下时序累积效应的研究方法已不再适用，气-固耦合效应研究对表征流场特性的精细化参数提出了迫切需求。光谱学测量方法可以直接反映宏观物理效应中的量子跃迁过程，这一优势为深入微观原子尺度研究气-固耦合效应提供了技术支撑。
本文利用辐射光谱和激光吸收光谱测量技术的优势，围绕防热材料与离解气流间的气-固耦合效应问题，提出多方法融合的光谱视角研究方案。在准静态等离子体炬流场环境下完成方案的实验验证后，将该方案应用于高频感应等离子体风洞流场环境下材料表面的气-固耦合效应研究，重点针对碳化硅、碳/碳复合材料表面的反应路径及耦合机制开展实验研究，此外，利用该方案探索了磁流体调控下隔热瓦材料表面气-固耦合效应的响应机制。具体内容如下：
基于所构建的光谱视角研究方案，重点针对放电功率和压强对电感耦合等离子体光谱特性的影响开展实验研究。利用成像技术、辐射光谱技术和激光吸收光谱技术同步获得了宽波段内不同粒子的空间分布特征和时序演化特征，根据辐射光谱特性和原子平动温度及数密度对等离子体流场品质开展分析，总结了放电功率和压强对等离子体流场空间分布特征和时序稳定性的影响规律，为在该平台开展防热材料气-固耦合效应实验研究奠定基础。
利用光谱视角研究方案，在上述电感耦合等离子体炬流场中开展防热材料气-固耦合效应实验研究。在该实验台产生的准静态等离子体环境下，重点针对以微烧蚀防热主导的碳化硅材料、以烧蚀型防热主导的碳/碳复合材料开展研究，获得了材料表面氧原子平动温度、氧原子数密度以及产物粒子辐射光谱的动态演化特性和空间分布特征，初步分析了两类材料在气-固界面处的特点。
在上述实验基础上，将光谱视角研究方案应用于高频感应等离子体风洞中碳化硅高温界面气-固耦合效应的实验研究，同时将石英作为参考材料进行对比分析。根据辐射光谱动态演化特征辨析了材料高温界面处的反应路径及竞争机制，基于激光吸收光谱透射光强特性分析了材料轮廓演化过程及其对表面反应的影响，发现碳化硅高温界面处的反应活性和轮廓演化动态特性均高于石英材料表面；此外，利用激光吸收光谱技术定量测量了材料表面的平动温度和数密度，对比分析发现对于催化特性更高的碳化硅材料，其表面氧原子数密度动态演化特性比石英材料更强，且其数值更低、轴向梯度更大。
基于上述相同的高焓等离子体加热环境，将光谱视角研究方案应用于碳/碳复合材料高温界面的气-固耦合效应实验研究。根据特征粒子辐射光强以及吸收光谱中激光透射光强的时序演化特性进行分析，发现碳/碳复合材料表面的反应进程存在氧化反应主导、反应竞争主导、氮化反应主导以及材料表面退移主导四个主要阶段。此外，激光吸收光谱技术针对氧原子平动温度和数密度开展定量测量，通过分析两参数的时序演化和空间分布特性，发现了其与化学反应机制间存在紧密的依赖关系。
利用光谱视角研究方案，探索磁流体调控下隔热瓦材料表面气-固耦合效应的响应机制。在高频感应等离子体风洞加热环境中，分别对加载N极向外磁场、加载S极向外磁场以及未加磁场条件的隔热瓦材料开展实验，通过对比材料表面光谱特性的差异性，发现相比于N极向外磁场和未加磁场工况，加载S极向外磁场工况下，隔热瓦表面温度、氧原子辐射强度、材料热解程度以及氧原子数密度消耗量均显著降低。

Gas–surface interactions between thermal protection materials (TPMs) and high-enthalpy nonequilibrium flow become increasingly significant as the velocity of the hypersonic vehicle continues to be higher, which severely affecting the aerodynamic thermal load on the vehicle's thermal protection system. Elucidating the underlying mechanisms of the gas–surface interactions has become one of the critical issues to be addressed in the development of hypersonic vehicles. Regarding these issues, the traditional research approach, which is guided by macroscopic parameters such as surface temperature and treats the catalytic properties of materials as constants (diminishing the influences induced by the dynamic characteristics of the interface), is no longer reliable. Breaking through the cognitive bottleneck of the gas–surface interactions has been in an urgent demand for refined parameters that depict the finer details of the multi-physics between high-enthalpy gas flow and material surfaces. Spectroscopic measurement techniques, with quantum-state-specific characteristics, can provide a unique perspective for gas–surface interactions. It enables the in-depth analysis of reaction mechanisms at the microscopic molecular and atomic scale, and is promising to bridge the gap between the macroscopic phenomena with quantum transitions.
Based on optical emission spectroscopy (OES) and laser absorption spectroscopy (LAS), a research approach based on spectral diagnosis has been established in this work, providing a spectral insight of the gas−surface interactions. After this approach was validated in a quasi-static plasma flow, the proposed approach is applied to gas−surface interactions in a high-enthalpy plasma flow provided by a wind tunnel. Focuses are placed on reaction pathways and coupling mechanisms on the silicon carbide (SiC) and carbon/carbon (C/C) composite materials. Furthermore, this approach is utilized to investigate the mechanisms of gas-solid coupling effects on the surface of insulating tile materials under magnetohydrodynamic (MHD) control. The specific content includes:
Based on the established approach, experimental investigations are conducted to find the influence of the charge power and the gas pressure to the plasma properties. Utilizing the imaging technology, OES and LAS, the spatial distribution features and temporal evolution characteristics of emission intensity within a broad wavelength range were simultaneously obtained. Analysis was conducted on the plasma flow field quality based on radiative characteristics, atomic translational temperature and number density. Influence patterns of the discharge power and pressure on the spatial distribution characteristics and temporal stability of the plasma flow field has been summarized, laying the foundation for conducting experiments on the gas–surface interactions of TPMs on this platform.

Utilizing the spectroscopic perspective research approach, experiments on the gas–surface interactions of TPMs were conducted in the flow field generated by the inductively coupled plasma generator. Within the quasi-static plasma produced by this experimental setup, the study focused on SiC dominated by micro-ablation thermal protection and C/C composite dominated by ablative thermal protection. Emission spectra of various particles, translational temperature and oxygen atom number density of the atomic oxygen and their dynamic evolution characteristics and spatial distribution features have been obtained, providing a preliminary analysis of the characteristics of these two types of materials at the gas-surface interface. Additionally, repeated heating experiments were carried out on these materials, the influences of the repeated heating to the flow properties at the interface have been analyzed.
Based on the aforementioned experiments, the spectroscopic perspective approach was extended to the study of gas–surface interactions at the high-temperature interface of SiC in a high-frequency inductively coupled plasma (ICP) wind tunnel, with quartz used as a reference material for comparative analysis. The dynamic evolution features of the radiative spectra were used to discern the reaction pathways and competitive mechanisms at the materials' high-temperature interfaces. The effect of surface profile evolution on reaction mechanisms was analyzed based on the characteristics of the transmitted laser intensity of the LAS. It was found that the reaction activity and the temporal dynamics at the high-temperature interface of silicon carbide were higher than those on the quartz surface. Additionally, the translational temperature and number density on the material surface were quantitatively measured using LAS. Comparative analysis revealed that SiC materials with higher catalytic properties exhibited higher dynamic characteristics of surface oxygen atom number density, which also presented lower values and greater axial gradients compared those to quartz.
Under the same high-enthalpy plasma heating environment, the spectroscopic perspective research approach was applied to C/C composite regarding the gas−surface interactions. Based on the temporal evolution characteristics of emission spectra and transmitted laser intensity in LAS, it was found that the reactions on C/C composite sequentially encompassed four dominant processes: oxidation-dominant, intense competitive, nitridation-dominant and recession dominant period. The temporal evolution and spatial distribution of the quantitative LAS results were found a close relation with chemical reaction mechanisms.
The spectroscopic perspective approach was also used to preliminarily explore the gas−surface interactions on insulation tiles under MHD control in a high-frequency ICP wind tunnel. Experiments were performed on different magnetic field conditions including N-pole, S-pole and without a magnetic field. By comparing the differences in the spectral characteristics, it was discovered that, compared to those in the N-pole and without a magnetic field condition, there was a significant reduction in the surface temperature, the O atom emission intensity, the extent of material pyrolysis, and the consumption of O atom number density the insulation tiles under S-pole condition.