Mobilities of charge carriers generated by corona discharge in low temperature helium gas

This paper describes a new method of apparent mobility measurement in a space charge flow field generated by corona discharge. The positive helium ion mobility at cryogenic temperatures down to 4.2 K is newly measured and the results obtained agree well with theoretical values for the atomic helium ion He⁺. The mobility of negative charge carriers is also obtained at 4.3 K. The results suggest the transition from free electron to electronic bubble in dense helium gas and support the discharge mechanism of a negative pulse corona in which an electronic bubble has the same space charge effect as a negative ion in electronegative gas.