Simulation of a Linear-Format Crossed-Field Amplifier with Modulated Electrons

Crossed-Field Amplifiers (CFAs) are vacuum electron devices characterized by moderate power, gain, and bandwidth; however, their performance is often limited by cathode emission controllability [1]-[3]. This work presents a simulation, performed using VSIM, of cathode electron modulation in a linear-format, compact, low-gain CFA aimed at improving electron-beam controllability and enhancing gain [4]. The simulated CFA incorporates a slow-wave circuit (SWC) composed of a PTFE dielectric and a perfect electric conductor. The device operates with a 2 kV anode-to-sole voltage, a 0.2 kV cathode-to-sole voltage, a 0.011 T magnetic field, a continuous beam current of 150 mA, an RF input power of 15 W, a 20 mm anode-to-sole gap, and an operating frequency of 600 MHz. Modulated electron emission is implemented in the simulation using a mathematical model based on Fowler-Nordheim (FN) theory, with FN constants extracted from current-voltage measurements of gated field emitter devices. A 20 Vpp, 600 MHz sinusoidal modulation superimposed on a DC bias produces an average electron beam current of 150 mA. Results demonstrate the influence of electron modulation and electron-RF signal phase on electron trajectories and electron-SWC interaction looking to achieve a 5-8 dB gain. These results will support the validation of a CFA experimental setup with similar characteristics and provide a complementary study of CFA device physics.