The Calculation Method of Ion Mobility Spectrum for Single-measurement-electrode Gerdien Tubes

The ion mobility and ion density are key physical parameters in research of ion flow field of high-voltage DC (HVDC) transmission lines. The Gerdien tube is one of the practical tools that can be utilised in situ measurement of ion mobility and ion density of coronated lines. The mobility spectrum, connecting the ion mobility and ion density, is an effective approach in analysis of the characteristics of corona ions and the effects of environmental factors on them. In previous studies, single measurement-electrode Gerdien tube is frequently used to get the mobility of one single ion via graphical method or the total ion density when the tube is operating as a counter. To enable it to obtain the ion mobility spectrum, a method is devised by the analysis of graphical method and the transition phenomenon in current–voltage characteristics of the tube. Furthermore, the method is applied to the raw data of current–voltage characteristics published in the literatures. The ion mobility spectra are obtained and compared with those having been reported. By doing this, the method is validated. This new approach makes applications of Gerdien tubes more advantages in experimental researches of ion flow field of HVDC transmission lines.