電子衝撃加熱型電子銃の改良

Abstract

An electron-heated point cathode gun has been studied for the development of a high brightness gun with a long cathode life. In this gun, only the tip part of the tungsten point cathode is heated by the bombardment of the electrons emitted from an annular gun set inside of the Wehnelt cylinder. The emission characteristics of the gun show that this gun can be operated in the same way as a conventional triode gun. Besides the electron beam emitted thermally from the cathode tip, however, the backscattered and secondary electrons arrive at the anode. It was found that most of these electrons are caused by the bombarding electrons hitting the Wehnelt aperture and are suppressed by modification of the electrodes arrangement.