Charging of Fine Particles in Negative Corona near Sparkover

The conventional theory for the charging of fine particles assumes that only ions are responsible for particle charging. Thus, the possibility of the presence of free electrons is neglected. Tests reported in this paper indicate that free electrons cannot be neglected and that these free electrons may be responsible for the abnormally high particle charge or mobility in negative corona near sparkover. In air it is assumed that oxygen molecules are primarily responsible for the attachment of free electrons to form negative ions. In stack gases where the percentage of oxygen is low, there may be other gas components that may tend to increase or decrease the percentage of free electrons. Measurements of particle mobility are made to study the effect of various gas components that may be of importance in stack gases.