Study of radiation effect on thermal conduction in solids using picosecond thermoreflectance technique and ion irradiation

利用皮秒热反射技术和离子辐照研究辐射对固体热传导的影响

• 批准号: 11308018
• 负责人: NAGASAKI Takanori
• 金额: $ 19.35万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11308018/
• 关键词: thermoreflectance; thermalconduction; thermal diffusivity; radiation effect; lattice defect; pulse laser; 熱拡散率; 熱反射法

We have developed an apparatus based on the transient thermoreflectance technique to measure the thermal diffusivity of thin surface layer of a bulk material as well as thin film on a thick substrate.- We observed thermoreflectance signal for aluminum sheets, aluminum film, gold film, stainless steel sheets.- Transient thermoreflectance for the aluminum sheets obeyed the parabolic one-step radiation heating model (POS model). This means that in aluminum, the electron-phonon thermalization time is much shorter than the measurement time scale so that a local equilibrium between electrons and phonons is achieved throughout the measurement. The thermal diffusivity determined by curve fitting was, however, not so reliable because of the undesirable property of the theoretical curve and the large thermal diffusivity of aluminum.- Transient thermoreflectance for the gold film was much faster than that for the aluminum sheets. This is because the thermalization time in gold is comparable to the measurement time scale; for a few picoseconds after pulse heating, the electron temperature is higher than the lattice temperature. It is cooling of the sample surface due to the relaxation of and/or heat transfer by these non-equilibrium electrons that was detected as transient thermoreflectance.- Transient thermoreflectance for the stainless steel sheets was basically described by the POS model. The thermal diffusivities determined were an order of magnitude smaller than those of aluminum.- We tried to measure the thermal diffusivity of an aluminum sheet irradiated by 2 MeV He ions. Although the degradation due to the irradiation was not clear in this sample, we believe the apparatus itself is applicable to determine the thermal diffusivity of ion-irradiated materials. We are trying to measure the thermal diffusivity of heavily irradiated materials and will discuss the radiation effect on thermal conduction in solids.

我们已经基于瞬态热室内技术开发了一种设备，以测量厚材料的薄表面层的热扩散性以及在厚的底物上的薄膜。-我们观察到铝制薄膜，铝制薄膜，金色薄膜，不锈钢材料的铝薄片的热反射信号。 模型）。这意味着在铝制中，电子 - 音波热化时间比测量时间尺度短得多，因此在整个测量过程中可以实现电子和声子之间的局部平衡。然而，通过曲线拟合确定的热扩散率并不是那么可靠，因为理论曲线的不良特性和铝的较大热扩散率。-金膜的瞬时热反射率要比铝片的瞬时热我表现要快得多。这是因为黄金中的热化时间与测量时间尺度相当。对于脉冲加热后的几秒钟，电子温度高于晶格温度。由于这些非平衡电子的放松和/或热传递的放松，它是样品表面冷却的。确定的热扩散度比铝的热扩散率小。尽管该样品中由于辐照引起的降解尚不清楚，但我们认为该设备本身适用于确定离子辐照材料的热扩散率。我们正在尝试测量重辐照材料的热扩散率，并将讨论对固体热传导的辐射影响。