系统探究和实验验证磁共振机理对提高近场辐射传热的影响

According to the distance between two objects and the characteristic wavelength of their thermal radiation, the radiative heat transfer can be divided into far-field radiation and near-field radiation. When the distance is equivalent to or even smaller than the characteristic wavelength, it is called near-field radiation. Near-field radiative heat transfer can exceed the blackbody radiation limit with several orders of magnitude, thus it has a huge application prospect. In order to further enhance the near-field radiative heat transfer, people tried various mechanisms like surface plasmon/phonon polaritons, hyperbolic metamaterial, and epsilon-near-zero/pole modes. Compared to other mechanisms, which require the similarity between the resonance frequencies of the emitter and the receiver to enhance near-field radiation, the mechanism of magnetic polariton demonstrated by the project applicant in 2016 is not restricted to this rule. Magnetic polariton has its unique advantages and great value in systems where the emitter and the absorber are quite different, like near-field thermophotovoltaic system. The current work only demonstrated the existence of magnetic polariton in the near-field radiation, but how to maximize its impact on enhancing near-field radiative heat transfer and the relationship between magnetic polariton and other mechanisms need to be further explored. The research content of this project is to systematically investigate the influence of magnetic polariton on near-field radiative heat transfer and finally to verify it by means of experimental measurement, to achieve the purpose of maximizing the near-field radiation. The scientific significance of this project is to seek a new path to further enhance the heat transfer in near-field radiation and further promote the practical applications based on near-field radiation.

依据物体间的间距与热辐射峰值波长的大小关系，辐射传热可分为远场辐射和近场辐射。当物体间距与热辐射峰值波长相当甚至更小时为近场辐射换热范畴，其换热量可超出黑体辐射换热热流几个数量级，具有巨大的应用前景。目前已提出的增强近场辐射传热的机理包括表面等离子体/声子共振、双曲超材料、近零/近极超材料，它们均需要发射体和吸收体共振频率相近才能增强近场辐射传热。项目申请人于2016年论证的磁共振增强机理则不受限于此，利用该机理可使得发射体和吸收体在无法满足材料相似条件的应用中获得近场辐射换热增强。目前磁共振机理的研究仅论证了其在近场辐射传热中是否存在的问题，对于如何最大化磁共振对近场辐射传热的增强影响以及磁共振与其他机理之间的相互作用问题亟待进一步探究。本项目拟系统探究磁共振对近场辐射传热的影响和强化机制，并通过实验测量进行验证。该项目研究的科学意义在于为更进一步提高近场辐射传热寻求新的路径。

与远场辐射不依赖物体间间距不同的是，近场辐射传热量随着物体间间距的减小而迅速增加，可超出远场黑体辐射极限几个数量级，在热管理和光电转换等领域具有重要的应用前景。而探究新的机理用于进一步提高近场辐射传热量，人们也一直在做着不懈的努力。本项目的研究内容就是系统探究磁共振机理对近场辐射传热的影响，以及与其他共振机理之间的相互作用，达到最大程度提高近场辐射传热的目的。本项目探究了包括磁共振、米氏共振、表面等离子体共振等多种机理之间的相互耦合关系，以及对近场辐射传热的影响机制，实现了不同材料和结构组合间近场辐射传热的进一步提升。同时，在现有纳米柱和纳米位移法基础上提出了精度更高的纳米传感-位移法用于近场辐射传热的测量。具体重要结果及科学意义包括：（1）探究了磁共振与米氏共振机理之间的耦合关系，实现了全介质超材料间近场辐射传热的进一步提升，使得近场辐射传热的提升不再只依赖于金属或极性材料；（2）探究了二维超材料间的近场辐射传热，在表面等离子体共振机理主导作用下，通过激发高波矢表面等离子体共振，实现了二维材料间近场辐射传热数量级的提升；（3）基于磁共振、表面等离子体共振机理对近场辐射传热提升作用的理解，提出了以石墨烯为中间体的三体近场热辐射调制器，能够实现近场辐射传热量在大范围内的动态调控，在热管理器件中具有重要应用前景；（4）通过精确求解超材料间的近场辐射传热，系统探究了有效介质理论在近场辐射中的适应性，提出了其适用范围，对近场辐射传热计算的理论发展具有重要意义；（5）通过耦合多维度纳米尺度的传感和位移系统，提出了精度更高的纳米传感-位移法用于近场辐射传热的测量，并完成实验平台的初步搭建，该方法的提出有望解决现有方法无法动态捕捉由于温差或机械振动带来的表面实时形变信息的缺陷，从而进一步提升近场辐射传热测量精度。