The effect of space-charge on the secondary current in a triode

Abstract

When electrons strike a surface with sufficient velocity, secondary electrons may be emitted by it, some or all of which may be collected by a suitable electrode having a higher potential than the emitting surface. (“Secondary electrons” are here taken to mean all electrons which leave the surface, whether reflected, rediffused, or actually emitted by the surface.) In the work to be described, a triode is considered, in which the anode receives electrons from the cathode, and emits secondary electrons which are collected by the grid, which is maintained at a higher positive potential than the anode. In the experimental work, a triode with an axially symmetrical configuration of electrodes was used, and such a triode will be considered in the theoretical work.