CHARGED PARTICLE BEAM EMITTING DEVICE

摘要

In accelerating tubes that use conductive insulators, the dopant density on the surface becomes non-uniform, which may make the surface resistance of the conductive insulator non-uniform. The problem addressed by the present invention is to maintain the electric potential distribution on the inner surface in the vertical direction constant without regard to the circumferential direction, even in such cases. A number of circular grooves are provided on the inner surface of the conductive insulator accelerating tube and a metal is metallized along the inside of the grooves. Since the electrical potential of the metallized region on the inner surface of the accelerating tube is uniform even if the resistance of a particular portion of the inner surface of the accelerating tube is different from the surrounding surface, the electrical potential distribution in the vertical direction on the inner surface of the accelerating tube can be maintained at approximately the same potential without regard to the circumferential direction. As a result, there is no horizontal force acting on the electron beam that passes through the center axis, electrical potential gradient is also maintained almost constant, and aberration reduction can be achieved.