A Chemiluminescent NOx-Detector for the Aircraft Measurement

Abstract

A high sensitive chemiluminescent detector of NOx (NO and NO2) has been developed for the aircraft measurements in the clean troposphere. The characteristics of the first version of the instrument is presented. The measurement of NO is based on the chemiluminescent reaction with ozone supplied in the instrument. For NO2 measurements, a ferrous sulfate converter is used to convert NO2 to NO before introducing into the reaction chamber. The pressure in the reaction chamber is controlled to be a constant value to keep the sensitivity stable in the ambient variable atmospheric pressure. The sensitivity response of the detector in the region below 10ppb is linear within 5% and has been found to be 250-300counts/s/ppb in the altitude range from the ground to 7km. The sensitivity of the detector is repeatedly checked during flights. The detection limit of NOx determined by the sensitivity and the fluctuation of the background signal is 10-15ppt.