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 $dalpha sim hbox{15}%$. 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.