黑体空腔发射率计算的蒙特卡罗模型

在均匀镜－漫反射假设的基础上，给出了利用蒙特卡罗方法计算黑体空腔有效发射率的数学模型。该模型首先使用光束跟踪方法求得等温空腔有效发射率，然后逆向跟踪各反射光束，考虑了空腔不等温性和环境辐射对空腔有效发射率的修正。利用该模型对中国计量科学研究院的低温黑体实际空腔进行了计算研究，结果表明：镜反射成分的影响取决于空腔形状和壁材表面光学性质；环境辐射总是增加空腔的有效发射率，腔口附近壁温分布对空腔法向有效发射率影响不大。

Monte Carlo model for calculaton of cavity effective emissivities

A Monte Carlo model is described for calculation of effective emissivities of uniform specular diffuse cavities. In the model, a new algorithm for tracing ray bundles is used to obtain isothermal cavity effective emissivity firstly, and then reversely trace route of the reflective rays which has been recorded, to consider the corrections caused by the non uniform temperature distribution along the cavity and surrounding radiation. Using the model, the effective emissivities of a low temperature blackbody of National Institute of Metrology of China were studied and calculated, some interesting conclutions were received as follows: the effect caused by specular reflection is subject to cavity shape and optical characters; surrounding radiation is always increasing cavity effective emissivities; temperature distribution near the aperture has little effect on the cavity normal effective emissivity.