Technical Note: Calibration device for the krypton hygrometer KH20

[摘要] A calibration device for krypton hygrometers (KH20, Campbell Scientific,Inc.) with variable path length is presented. This unit allows for in-situcalibrations of the krypton hygrometer, which is typically not very stableover time, during measuring campaigns. It was constructed mainly forapplication at high altitudes and low temperatures, where furtherimprovements are needed to the IR-hygrometers which are normally used. Thechanging path length requires that a changing concentration of the absorberbe simulated. Because oxygen absorbs more strongly than water vapour, thecalibration is made against oxygen and transferred to water vapour. Thedesign of the calibration instrument is made as one unit containing astepper motor system, PC and humidity sensor. For the calibration, it isnecessary to install the krypton hygrometer on this unit.

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