Experimental verification of low-velocity spread axis-encircling electron beam

Abstract

We have experimentally demonstrated a low-velocity spread, axis-encircling electron beam using a comparatively simple Pierce-type electron gun and single cusp magnetic field based on a recent theory [Jeon et al., Appl. Phys. Lett. 80, 3703 (2002)] developed with the assumption of small orbit gyration before the magnetic cusp, in which every physical property has been analyzed and the possibility of zero percent axial velocity spread was concluded. The velocity ratio and the axial velocity spread were measured to compare the theory with varied operation conditions of the electron gun. These results agree well with our hypothesis.