Development of the forced Rayleigh scattering method with CO_2 laser

本研究项目所取得的成果概括如下：1.利用强迫瑞利散射法，研制了一种利用CO2激光测量多种物质热扩散率的装置，该装置无需添加染料材料。该装置的特点是：光栅周期在20~300微米范围内可调，激光不仅可以从水平方向照射，还可以垂直照射到样品上。为了确定该装置适用于液体，我们用7-NSE电池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、样品厚度、加热时间等可调参数，找到了最佳的测量条件。我们开发了不需要电池窗口的自由表面加热法。验证了该方法在高温条件下的应用优势。对误差因素(光束偏心问题和样品厚度)进行了实验研究。用蓝宝石玻璃池测量了Li_2CO_3-Na_2CO_3-K_2CO_3=41.5：31.5：25.0摩尔%的混合物在677-970K温度范围内的热扩散率，重复性为+^-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%.