ELECTRON BEAM GENERATING DEVICE

摘要

PROBLEM TO BE SOLVED: To remarkably improve the ratio of a light emission current to a field emission current when excited by visible light in particular by using a metal carbide as a film at one end of a light guide. SOLUTION: This electron beam generating device 4 is formed as a photoelectric cathode 40. A sharp chip is formed at one end of a light guide 41, and a film 43 is provided in the region of the chip to be used as an emitter. A light source is connected to the other end of the light guide 41 by a proper method. The light guide 41 is constituted of a core 41a and a glass fiber having a cladding 41b. A metal carbide having a low work function is used for the film 43. An extracting electrode 44 charged positively against the photoelectric cathode 40 is provided to cause light emission by the visual light from the light source, and a light emission current is generated. The ratio of the light emission current against a field emission current can be remarkably improved when excited by the visible light in particular.