Experiment research of the axis-encircling large-orbit Cusp electronic-gun

The magnetic field solenoid is designed to satisfy for the positive-negative cusp magnetic field´s distribution by the experiment and simulation. The cusp magnetic field makes electron doing the axis-encircling large-orbit movement. The current is measured in the thermionic cathode electric gun. An experiment method of measuring the electron velocity ratio is put forward by catching light spot when electron holding some energy shock at a fluorescence glass. By measuring the radius of the light spot, the velocity ratio is calculated in experiment. The error is about 15% compared with experiment and theory result. The experiment is accumulated for optimizing X-band second harmonic gyro-TWT using helical waveguide later.