Flat emitter

摘要

A flat emitter comprises four current-supply heating legs. Half lighting for a small focus in which a current is supplied to heat only a region narrower and full lighting for a large focus in which a current is supplied to heat the entire region are selectable according to the combination of the legs. Either one of a set of the two full-lighting current-supply heating legs for the full lighting and a set of the two half-lighting current-supply heating legs for the half lighting is linearly formed, and the other is formed to be bent plural times in zigzag to set the space between the full-lighting current-supply heating leg and the half-lighting current-supply heating leg, which are adjacent to each other, at their terminals to be larger than the space at their base parts.

主权项

1. A flat emitter used for an electron source, the flat emitter comprising:
four current-supply heating legs; wherein half lighting for a small focus in which a current is supplied to heat only a region narrower than an entire region to emit electrons and full lighting for a large focus in which a current is supplied to heat the entire region to emit electrons are selectable according to the combination of the legs, all of the four current-supply heating legs are folded at a base part of an electron emission portion, and either one of a set of the two full-lighting current-supply heating legs for the full lighting and a set of the two half-lighting current-supply heating legs for the half lighting is linearly formed, and the other is formed to be bent plural times in zigzag to set the space between the full-lighting current-supply heating leg and the half-lighting current-supply heating leg, which are adjacent to each other, at their terminals to be larger than the space at their base parts.