Characteristics of an ion induced secondary emission electron gun

摘要

This paper presents some fundamental characteristics and performance of a secondary emission electron gun (SEEG) using a pulsed glow discharge wire ion plasma source (WIPS). The positive helium ions extracted from WIPS are accelerated in vacuum toward a negatively biased cold cathode surface, which is set oblique to the ion loci in order to inject the secondary electrons emitted perpendicular to the foil window. The physical mechanisms governing the characteristics such as space charge, charge exchange and secondary electron emission have been reviewed. The dependence of such characteristics on the accelerating voltage of the incident ion and on the ion incidence position has been experimentally investigated. The experimental results are discussed together with available theoretical models of each characteristic to establish the relative understanding of such phenomena in a side-extraction-type SEEG. The experimental results are further discussed in the light of a self-developed numerical simulation using a finite element method, which presents a good understanding of particle trajectories as well as potential distribution inside the gun geometry. [References: 25]