空间低温辐射计黑体腔与光电不等效性研究

	空间低温辐射计黑体腔与光电不等效性研究
	方茜茜
学位类型	博士
导师	方伟
	2014-07
学位授予单位	中国科学院大学
学位专业	光学工程
摘要	低温辐射计+激光光源的测量模式将地基光辐射测量精度提高至少十倍，得到可溯源至国际单位制（SI）的光辐射测量结果。工作在低温（4K-30K）的辐射计，由于黑体腔金属材料OFHC铜热学性质极大改善，能够有效提高辐射测量灵敏度和降低响应时间常数。借鉴地面低温辐射计的测量模式，在空间中以太阳光为稳定光源，建立空间低温辐射计，将目前空间光辐射测量精度提高十倍，分别在0.02%和0.1%的不确定度水平上测量太阳总辐射功率和光谱辐射功率。在空间中得到可溯源至SI的光辐射测量结果。本文首先对空间低温辐射计的结构、工作原理进行阐述。通过建立光功率测量的数学模型，得到影响测量结果的9个影响量。经过不确定度的归类以及粗略分配，提出两项对测量结果影响深远、目前尚未被深入探究的量——吸收率和光电不等效。本论文主要针对吸收率和光电不等效进行深入的理论研究和实验测量。为得到超高精度的太阳总辐射测量结果，入射到黑体空腔的光线应尽可能被吸收。通过蒙特卡罗算法计算黑体空腔有效吸收率，指导太阳总辐照度腔设计。理论上得到吸收率近似为1（0.99999）的空腔。为尽量测准黑体空腔的吸收率，减小影响量对总测量不确定度的贡献，提出同时引入白板、黑板和空腔对比测量的方法，经过多次测量能够使的相对标准不确定度满足要求。对光电不等效的研究，首先根据常温辐射计(SIAR)的实验结果，建立等效的有限元模型，ANSYS热分析研究发现：多层的锥腔传热结构可以简化成单层——主体层的传热。然后，通过格林函数法求解SIAR圆锥腔的导热微分方程发现：只有对黑体腔的认识深入到微元的程度，才能全面掌握黑体腔的响应特性。这给由于光电加载区域差异引入的光电不等效的研究提供强大的计算方法。在有限元分析中，通过细化网格，将单元近似看成微元，对SIAR微元的响应特性进行计算，就能够掌握所有情况下黑体腔测温点总温度响应值。最后，有限元法求解空间低温辐射计TSP腔和HS腔的微元响应关系。由于缺乏实验数据，无法建立准确的有限元模型，在假设TSP腔有限元模型上计算微元响应关系，得到TSP腔和HS腔的格林函数解。对空间低温辐射计黑体腔的计算，目的不是得出准确的结果，旨在捋顺和指明研究思路和方法，为后续表征TSP腔光电不等效和HS腔响应特性打下扎实的理论基础。
其他摘要	Optical radiation measurement accuracy is improved by at least tenfold on the ground by Cryogenic Radiometer and laser, and measurement results could be traceable to the International System of Units. Because of greatly improved thermal properties of OFHC copper, the sensitivity and response time constant of radiometer were optimized greatly in a very low temperature (4K-30K). Learning from Cryogenic Radiometer on the ground, Spatial Cryogenic Radiometer is intend to be bulided, and the current spatial optical measurement accuracy will be improved tenfold with stable sunlight as light source. A 0.02% and 0.1% level of uncertainty will be achieved for solar total power and spectral power, respectively. Optical radiation measurements which can be traceable to SI will be achieved in space.Firstly, the structure and working principle of spatial cryogenic radiometer were elaborated. Through the establishment of a mathematical model of optical power measurements, nine factors were found. After a rough classification and distribution of total uncertainty, two main factors—the absorptivity and nonequivalence were attended which are very important but not yet explored in depth. This two main factors were researched theoretically and experimentally in depth in this paper.In order to get a ultra-high-precision measurement of solar total power, the radiation should be almost completely absorbed. The Monte-Carlo method was used to calculate the absorptivity of black cavities, and the calculation results directed the research of the shape of cavities. A almost perfect cavity was designed theoretically. In order to measure the absorptivity of blackbody cavities precisely, a new measurement method was proposed which included a standard whiteboard, a standard blackboard and blackbody cavity. After several measurements, the measurement accuracy can be enabled.On the research of nonequivalence, a finite element model was established according to experimental results in vacuum. From the ANSYS thermal analysis, we found that multilayer cavity structures can be simplified to monolayer structure.Then, through solving SIAR’s heat conduction equations, we found that in order to fully grasp the response characteristics of the blackbody cavity, elements’ response characteristics were important. This is an effective method for the calculation of nonequivalence which is due to different optical or electrical loading areas. Through the calculation of elements’ response in FE analysis, the response of the blackbody cavity can be grasped.Finally, the FE method was used to solve the TSP and HS cavities’ response. Due to the lack of experimental data, the TSP and HS cavities’ FE model were based on the assumption. The calculation aim of Spatial Cryogenic Radiometer was not for accurate results, but for clear calculation ideas and effective calculation methods. The aim of this part of work is to establish a solid theoretical basis for subsequent research.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41403
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	方茜茜. 空间低温辐射计黑体腔与光电不等效性研究[D]. 中国科学院大学,2014.

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