Abstract A scanning mobility particle sizer (SMPS) is one of the most widely used instruments to obtain size distribution for atmospheric particles. In an SMPS measurement, a voltage scanning process on a differential mobility analyzer is required, and it typically takes 30 s to 120 s to obtain one entire size distribution. A size distribution obtained by an SMPS measurement might have significant deviations from actual values due to the scanning process when the measured particle concentrations change over time. In this study, we introduce an analytical approach for estimating particle size distribution under exponentially decaying and growing particle concentrations. The analytical SMPS results are validated by performing experiments using exponentially decaying particle concentrations under the same conditions. Furthermore, the effects of a decay parameter, initial size distribution, and scan time are evaluated, and the deviations from actual (real or true) size distributions obtained by an exact solution are analyzed. Geometric mean diameters and standard deviations of the size distributions from SMPS results increase or decrease with exponentially decaying or growing concentrations, respectively, and total concentrations estimated by the analytical SMPS approach are significantly underestimated or overestimated compared to real total concentrations. While SMPS measurements have been widely employed in various applications such as atmospheric particle characterization in highly variable particle concentrations versus time, very few studies on the influence of changing concentrations on SMPS measurements have been conducted. Therefore, the introduced analytical approach and findings provide valuable insight into the importance of accurate SMPS measurements with changing particle concentrations. Copyright © 2020 American Association for Aerosol Research

中文翻译：

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指数衰减和增长浓度对扫描迁移率粒度仪粒度分布的影响

摘要 扫描迁移率粒度仪（SMPS）是获得大气颗粒粒度分布最广泛使用的仪器之一。在 SMPS 测量中，需要在差分迁移率分析仪上进行电压扫描过程，通常需要 30 秒到 120 秒才能获得一个完整的尺寸分布。当测量的颗粒浓度随时间变化时，由于扫描过程，通过 SMPS 测量获得的尺寸分布可能与实际值有很大的偏差。在这项研究中，我们引入了一种分析方法，用于在指数衰减和增长的颗粒浓度下估算粒度分布。通过在相同条件下使用指数衰减的粒子浓度进行实验来验证分析 SMPS 结果。此外，评估衰减参数、初始尺寸分布和扫描时间的影响，并分析与通过精确解获得的实际（真实或真实）尺寸分布的偏差。SMPS 结果的几何平均直径和尺寸分布的标准偏差分别随着浓度的指数衰减或增长而增加或减少，并且与实际总浓度相比，分析 SMPS 方法估计的总浓度显着低估或高估。虽然 SMPS 测量已广泛应用于各种应用中，例如随时间变化的高度可变的粒子浓度中的大气粒子表征，但很少对浓度变化对 SMPS 测量的影响进行研究。所以，引入的分析方法和发现提供了宝贵的见解，了解随着粒子浓度变化而进行准确 SMPS 测量的重要性。版权所有 © 2020 美国气溶胶研究协会