Electron beam generator

摘要

The invention relates to an electron beam generator for generating an electron beam, comprising an electron source and an extractor. The combination of electron source and extractor in use forms a negative lens, wherein said extractor has a positive voltage with respect to the source. The extractor and the electron source are positioned such that, in use, a space charge limited region is present between them. In an embodiment, the extractor is a planar extractor. In another embodiment, the source is a thermionic source.. The generator may comprise an illumination system for collimating the electron beam.