Design of a Triodelike Electron Gun for Millimeter-Wave Gyrodevices

A computational study has been made on the design of a 150-kV triodelike switchable electron gun. A smooth magnetic cusp arrangement was used to produce an axis-encircling beam. Numerical optimization of this arrangement led to a gun design that produced beam parameters of $I_{b} \sim \hbox {6} \hbox {A}$ , $\alpha = \hbox {1.2}$ , and $d\alpha \sim \hbox {15}%$ . It has also been shown that this triode design can produce beam suppression at $\sim$ 2 kV while not interfering with the beam parameters under operation conditions.