Sources of Multi-Electron Emission in Very Low Dark Cureit Image Intensifiers

High gain, multi-stage cascade image intensifiers with Sb (KNa) bi-alkali input photocathodes exhibit exceptionally low dark current. Because of the imaging properties of these tubes, the spatial distribution of dark current events, especially those involvirf instantaneous multielectron emission, can be investigated to yield information on the causes of dark current sources which are not related to the thermal conditions of the photocathode.