Optical realization of the pascal-Characterization of two gas modulated refractometers
Optical realization of the pascal-Characterization of two gas modulated refractometers
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DOI：
10.1116/6.0001042
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发表时间：
2021-07-01
影响因子：
1.4
通讯作者：
Axner, Ove
中科院分区：
文献类型：
--
作者：
Silander, Isak;Forssen, Clayton;Axner, Ove
通过测量气体的活度和温度，可以根据基本原理计算出气体的压力。目前最灵敏的仪器是基于法布里-珀罗腔，其中激光器用于探测腔模式的频率。然而，为了获得最佳精度，这种系统的实现需要出色的机械稳定性。气体调制折射法（GAMOR）先前已经证明了减轻波动和漂移的影响的令人印象深刻的能力，由此它可以提供高精度（亚ppm，即，百万分之几或低于10（-6））的气体活度和压力的评估。在这项工作中，对两个独立的基于GAMOR的折射计进行了单独表征，相互比较，最后与校准的自重活塞规进行比较，以评估4-25 kPa范围内的压力。第一个系统，称为固定光学帕斯卡（SOP），使用一个微型固定点镓电池来测量温度。第二个系统，表示为可移动的光学帕斯卡（TOP），依赖于校准的Pt-100传感器。对于SOP和TOP，压力评估的扩展不确定度（k = 2）估计分别为[（10 mPa）（2）+（10 × 10（-6）P）（2）]（1/2）和[（16 mPa）（2）+（28 × 10（-6）P）（2）]（1/2）。虽然SOP的不确定度主要受氮摩尔极化率（8 ppm）不确定度的限制，但TOP的不确定度主要受温度评估（26 ppm）的影响。为了验证长期稳定性，在5个月的时间内对系统进行了相互比较。结果发现，所有测量值均在比较测量值（27 ppm）的估计扩展不确定度（k = 2）范围内。这验证了不相关误差的估计误差预算在这段长时间内保持不变。(C)2021年作者。
By measuring the refractivity and the temperature of a gas, its pressure can be calculated from fundamental principles. The most sensitive instruments are currently based on Fabry-Perot cavities where a laser is used to probe the frequency of a cavity mode. However, for best accuracy, the realization of such systems requires exceptional mechanical stability. Gas modulation refractometry (GAMOR) has previously demonstrated an impressive ability to mitigate the influence of fluctuations and drifts whereby it can provide high-precision (sub-ppm, i.e., sub-parts-per-million or sub-10(-6)) assessment of gas refractivity and pressure. In this work, two independent GAMOR-based refractometers are individually characterized, compared to each other, and finally compared to a calibrated dead weight piston gauge with respect to their abilities to assess pressure in the 4-25 kPa range. The first system, referred to as the stationary optical pascal (SOP), uses a miniature fixed point gallium cell to measure the temperature. The second system, denoted the transportable optical pascal (TOP), relies on calibrated Pt-100 sensors. The expanded uncertainty for assessment of pressure (k = 2) was estimated to, for the SOP and TOP, [(10mPa)(2) + (10 x 10(-6)P)(2)](1/2) and [(16mPa)(2) + (28 x 10(-6)P)(2)](1/2), respectively. While the uncertainty of the SOP is mainly limited by the uncertainty in the molar polarizability of nitrogen (8 ppm), the uncertainty of the TOP is dominated by the temperature assessment (26 ppm). To verify the long-term stability, the systems were compared to each other over a period of 5 months. It was found that all measurements fell within the estimated expanded uncertainty (k = 2) for comparative measurements (27 ppm). This verified that the estimated error budget for the uncorrelated errors holds over this extensive period of time. (C) 2021 Author(s).