Status of the high power Cusp gun

Certain gyro-type devices, including moderately high power, high harmonic gyrotrons and peniotrons, require an axis encircling electron beam. To develop practical and efficient devices of this type, it is necessary to first develop a gun that generates a high quality beam with low velocity spread and ripple. The authors present the development and low voltage testing of a Cusp electron gun designed to operate at 70 kV and 3.5 A beam current, with beam alpha (transverse to axial velocity ratio)=1.5, beam ripple