PPRTs偏差方程外推至-189.3442~156.5985℃温区的研究

Research on Extrapolation of PPRTs Deviation Equation to-189.3442~156.5985℃

由于ITS-90定义固定点数量少且温度间隔大,基于偏差方程的外推是解决超出温区范围的温度计标定问题的有效方法。实验对16支精密铂电阻温度计在超出温区范围标定,验证了固定点法和比较法偏差方程从窄温区范围外推至-189.3442~156.5985℃温区的可行性。实验结果表明:-38.8344~0.01℃温区新偏差方程外推至-189.3442℃的平均最大差值为5.2 mK;0~29.7646℃温区偏差方程外推至156.5985℃的平均最大差值为2.0 mK;基于比较法的偏差方程在-189.3442~156.5985℃温区的平均差值小于3.3 mK。3种方程均提高了精密铂电阻温度计在超出温区范围的外推精度,为星载黑体辐射源的量值溯源提供了数据支撑。

The traceability of precision platinum resistance thermometers(PPRTs)can be improved by using the fixed-points method defined by the International Temperature Scale of 1990(ITS-90).Due to the small number of fixed-points and the large temperature interval in ITS-90,the extrapolation based on deviation equation is an effective method to solve the problem of thermometer calibration beyond the temperature range.In the experiment,16 PPRTs were calibrated in the temperature range of-189.3442~156.5985℃to verify the extrapolation feasibility of the fixed-points method deviation equation and comparison method deviation equation.The experimental results showed that the average maximum difference using the new deviation equation from-38.8344~0.01℃was 5.2 mK when extrapolating to-189.3442℃;the average maximum difference using the deviation equation from 0~29.7646℃was 2.0 mK when extrapolating to 156.5985℃;and the average difference using comparison method deviation equation was less than 3.3 mK.All the three equations improved the extrapolation accuracy of PPRTs out of the fixed-points temperature range and provided supporting data for the traceability of spaceborne blackbody radiation source.