A simple negative ion mobility spectrometer(IMS)is designed and used to investigate the factors that influence the number and efficiency of electrons generated by the needle-ring pulsed corona discharge electron source.Simulation with Ansoft Maxwell 12 is carried out to analyze the electric field distribution within the IMS,and to offer the basis and foundation for analyzing the measurement results.The measurement results of the quantities of electrons show that when the drift electric field strength and the ring inner diameter rise,both the number of effective electrons and the effective electron rate are increased.When the discharge voltage becomes stronger,the number of effective electrons goes up while the effective electron rate goes down.In light of the simulation results,mechanisms underlying the effects of drift electric field strength,ring inner diameter,and discharge voltage on the effective electron number and effective electron rate are discussed.These will make great sense for designing negative ion mode IMS using the needle-ring pulsed corona discharge as the electron source.
