Abstract
A gas pressure measurement device is built based on the gas refractive index method, and the measurement range is from 10 kPa to 100 kPa, and the device is tested by a dual-cavity comparison method. The temperature of the two vacuum chambers is separately controlled and the two cavities are connected to ensure that the gas pressures in the two cavities are the same. Using high-purity nitrogen (6N) as the gas medium, under the condition of different gas pressures, the dual-cavity comparative measurements are conducted. The results show that the optical pressure gauge has a repeatability better than 30 × 10<sup>–6</sup>, which is significantly better than the commercial capacitive pressure gauge, indicating that this method has great potential applications. Sources of error and uncertainty in the measurement are analyzed, and it is planned to design a new system to improve the measurement.
Highlights
图 3 左:1#腔体控温结果,右:2#腔体控温结果,其中 A 为腔体侧面温度,B、C 为两端盖板温度 Fig. 3 Left: 1# cavity temperature controlled result, right: 2# cavity temperature controlled result, where A is the temperature of the side of the cavity, B and C are the temperatures of the cover plates at each end
图 6 充气过程中测温 sensor 读数,其中黄色部分为充气过程,绿色部分为充气稳定时 Fig. 6 The reading of the temperature sensor during the inflation process, the yellow part is the inflation process, and the green part is when the inflation is stable
Summary
刘洋洋 1,胡常乐 1,孙羽 1,2,王进 1,2*,胡水明 1,2 1 中国科学技术大学 化学物理系 合肥 230026 摘 要 本文搭建了基于气体折射率方法的气体压力测量装置,气体压力测量区间为 10kPa 至 100kPa,并采用双腔比对方法对装置进行检验。通过将两个真空腔体分别控温,并且真 空连通,以保证两个腔内气体压力相同。以高纯氮气(6N)为气体介质,在不同气体压力 条件下,得到了双腔对比测量的初步结果。结果显示,基于光学方法的气体折射率压力计重 复度好于 30ppm,显著好于商用电容式薄膜压力计,说明该方法具有很大潜力。本文还分析 了测量中的误差来源,并计划通过改进系统设计以提高测量精度。 关键词 计量学; 气体压力; 气体折射率; 双腔比对 几个世纪以来,低压区(1Pa-100kPa)的气体压力基准测量一直采用水银压力计,测量 依据的是公式P = ρgh,其中 h 是水银柱的高度,g 是水银压力计所在位置的重力加速度,ρ 是水银密度。重力加速度和水银密度的测量精度较高,因此水银柱高度 h 的测量精度决定了 最终气体压力的测量精度。目前世界上水银柱高度测量最精确的是由美国国家标准局 (National Institute of Standards and Technology , NIST)研制的超声水银压力计(Ultrasonic interferometry Manometer , UIMs ) , 其压力测量的不确定度为u = √(3mPa)2 + (2.6 × 10−6)2[1,2]。水银压力计以其测量精度高的优点,至今没有被其他测 量方法取代。
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