Dependence of the average mobility of ions in air with pressure and humidity

The ion mobility is the one of the basic parameters in the study on gas discharge. There are many environmental parameters affecting the average mobility of ions in air. Among them pressure and humidity are important factors. Until now there is no uniform average mobility of ions in air in practice. This paper presents the results of a series of experiments on the influence of pressure and humidity on the average mobility of ions in air. Firstly, an improved analysis method to deduce the average air ion mobility in air is presented with the help of an apparatus for generating parallel-plane ion flow field. Then, the mobility is measured in a climatic test cabinet. The positive and negative mobilities in the air with the pressure from 80 to 110 kPa and the relative humidity from 20% to 80% at the room temperature are provided. Finally, the rule of mobility-pressure-humidity variation curve is discussed and the specific formula for average mobility of ions in air with respect to pressure and humidity is then raised.