Development of the forced Rayleigh scattering method with CO_2 laser

本课题的研究成果总结如下：1。研制了一种用CO_2激光用强迫瑞利散射法在不添加染料的情况下测量多种物质热扩散率的仪器。该装置的特点是光栅周期可在20 ~ 300 μ m范围内调节，激光束既可以从水平方向照射，也可以从垂直方向照射在样品上。为了证实该装置可以适用于液体，我们使用7-nSe细胞窗测量了甲苯和水的热扩散率。通过实验考察，通过改变光栅周期、试样厚度、加热时间等可调参数，找到了最佳的测量条件。我们开发了不需要细胞窗的自由表面加热方法。结果表明，该方法在高温条件下具有明显的优越性。对误差因素（光束偏心问题和试样厚度）进行了实验研究。在677 ~ 970 K的温度范围内，用蓝宝石玻璃电池测量了Li_2CO_3-Na_2CO_3-K_2CO_3 = 41.5: 31.5: 25.0 mol%的混合物的热扩散率，重现率为+^^-10%。

The results obtained from the present research project are summarized as follows.1. An apparatus to measure the thermal diffusivity of wide variety of substances without adding the dye material using CO_2 laser by the forced Rayleigh scattering method was developed. The characteristics of the apparatus is that the grating period can be adjustable from 20 mum to 300 mum and laser beam can be irradiated not only from horizontally but vertically on the sample.2. In order to confirm that this apparatus can be applicable to liquids, we measured thermal diffusivity of toluene and water using 7-nSe cell windows. We found the optimum measuring conditions through experimental examinations by changing adjustable parameters such as grating period, sample thickness and heating time.3. We developed the free surface heating method which does not require the cell windows. It was verified that this method has the advantage when the method is applied to high temperature conditions.4. The error factors (the beam off-center problem and sample thickness) were experimentally investigated.5. Thermal diffusivity of the mixture of Li_2CO_3-Na_2CO_3-K_2CO_3 = 41.5 : 31.5 : 25.0 mol% was measured using sapphire glass cell in the temperature range from 677 K to 970 K with the reproducibility of +^^-10%.