Laser based modulated thermoreflectance (MTR) technique is an attractive method for measuring thermal conductivity in ion irradiated samples. Unlike laser flash analysis, traditionally used for measuring thermal conductivity in nuclear materials, the MTR method is sensitive to damage that is only a few micrometers thick. This allows MTR to detect damage resulting from a few MeV ion beam irradiation. MTR combined with tailored ion beam irradiations offers a promising opportunity for validation of lower-scale thermal conductivity models developed for irradiated materials. In this technique, a harmonically modulated laser pump heats the irradiated sample and a probe beam measures the temperature induced changes in the sample's reflectivity. Interpretation of the measured temperature profiles in ion irradiated samples is complicated by the nonhomogeneous damage profile and the presence of an additional thin metal transducer layer. In this work, we present a detailed analysis of the experimentally measured thermal wave profiles in UO₂ samples irradiated with 2.6 MeV H⁺ ions using different multilayer approximations of the damaged region. The limitation of an infinite damage layer approximation that assumes uniform damage across the thickness of the sample and neglects the undamaged region is discussed. Presented analysis outlines the method for determination of the applicability range for the infinite damage model. Finally, an analysis of the impact of point defects on thermal transport in irradiated samples is presented as an example for implementation of the MTR approach for validation of thermal transport models.

基于激光的调制热反射（MTR）技术是一种用于测量离子辐照样品中热导率的有吸引力的方法。与传统上用于测量核材料热导率的激光闪光分析不同，MTR方法对仅几微米厚的损伤敏感。这使MTR能够检测到由于几次MeV离子束辐照而造成的损坏。MTR与量身定制的离子束辐照相结合，为验证为辐照材料开发的小规模热导率模型提供了一个有希望的机会。在此技术中，谐波调制激光泵加热辐照的样品，而探测光束则测量温度引起的样品反射率变化。非均匀损伤曲线和附加的薄金属换能器层的存在使离子辐照样品中测得的温度曲线的解释变得复杂。在这项工作中，我们提供了对UO中实验测量的热波剖面的详细分析使用损坏区域的不同多层近似，用2.6 MeV H ⁺离子辐照_2个样品。讨论了无限损坏层近似的局限性，该局限假设整个样品厚度上的损坏均匀，而忽略了未损坏的区域。提出的分析概述了确定无限损伤模型适用范围的方法。最后，分析了点缺陷对辐照样品中热传输的影响，作为实施MTR方法验证热传输模型的示例。