Electric field discharge-type electron source

摘要

Increasing the volume or weight of zirconia which is a diffusion and supply source, to extend the life of a field-emission type electron source causes a problem that the diffusion and supply source itself or a tungsten needle is easily subjected to damage. As another problem, although it is considered to form the diffusion and supply source using a thin film to avoid the above-described problem, it is difficult to stably obtain practical life exceeding 8,000 hours. It has been found that practical life exceeding 8,000 hours is stably obtained by providing a field-emission type electron source that has no chips or cracks in a diffusion and supply source and that can extend life with a little bit of an increase in the amount of the diffusion and supply source.

主权项

1. A field-emission type electron source comprising: a needle obtained by sharpening one of tips of a rod-like single-crystal tungsten, and having zirconia formed to a predetermined thickness and a predetermined length on a side outer portion thereof as a diffusion and supply source, the one of the tips having a crystal plane (100); heating means for the needle; and a suppressor electrode, wherein
in the field-emission type electron source that allows electrons to be emitted by heating the needle to apply an electric field to the tip of the needle, when a length of the diffusion and supply source is L and a maximum thickness of the diffusion and supply source is t, t/L<3/50, and the thickness of the diffusion and supply source is in a range greater than or equal to 10 μm.