Abstract. One of the most important parameters to quantify an aerosol is the particle number concentration. Condensation Particle Counters (CPCs) are commonly used to measure the aerosol number concentration in the nanometer range. To compare the data from different measurement stations and campaigns it is important to harmonize the instrument specifications, which is why the Technical Specification CEN/TS 16976:2016 was introduced for CPCs. There, the parameters of the CEN-CPC are specified for standard pressure and temperature. However, CEN-CPCs are used in various surroundings, on high mountains or on airplanes, where they are exposed to low-pressure conditions. Here, we present the pressure-dependent performance (including the concentration linearity and counting efficiency) of two different models of CEN-CPCs, the Grimm 5410 CEN and the TSI 3772-CEN. We found that their performance at 1000 hPa and 750 hPa was in accordance with the CEN-technical-specifications. Below 500 hPa, the performance decreased for both CPC-models, but the decrease was different for the two models. To gain insight into the performance of the two CPC-models, we performed a simulation study. This study included simulations of the saturation profiles and calculations of internal particle losses within the CPCs. The simulations reproduced the overall performance decrease with decreasing pressure and reveal that the internal structure of the CPC has a significant influence on the performance. We anticipate our publication to provide a deeper understanding of the counting efficiency of CPCs and their pressure dependence. Our findings might be a starting point for new standards that include the pressure-dependent performance or they could help for designing new CPCs.

中文翻译：

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CEN 指定的冷凝粒子计数器的压力相关性能

摘要。量化气溶胶的最重要参数之一是粒子数浓度。冷凝粒子计数器 (CPC) 通常用于测量纳米范围内的气溶胶数浓度。为了比较来自不同测量站和活动的数据，协调仪器规格非常重要，这就是为 CPC 引入技术规范 CEN/TS 16976:2016 的原因。在那里，CEN-CPC 的参数是针对标准压力和温度指定的。然而，CEN-CPC 用于各种环境，如高山或飞机上，它们暴露在低压条件下。在这里，我们展示了两种不同型号的 CEN-CPC、Grimm 5410 CEN 和 TSI 3772-CEN 的压力相关性能（包括浓度线性和计数效率）。我们发现它们在 1000 hPa 和 750 hPa 下的性能符合 CEN 技术规范。在 500 hPa 以下，两种 CPC 模型的性能均有所下降，但两种模型的下降幅度不同。为了深入了解两种 CPC 模型的性能，我们进行了模拟研究。该研究包括 CPC 内饱和度曲线的模拟和内部粒子损失的计算。模拟再现了整体性能随着压力的降低而降低，并揭示了 CPC 的内部结构对性能有显着影响。我们期望我们的出版物能够更深入地了解 CPC 的计数效率及其压力依赖性。