Fowler-Nordheim Emission in the THz Hybrid Cavity

We present a novel concept of a miniature vacuum electronic device (VED), suitable for coherent electromagnetic wave generation in the THz range. While in a traditional VED a preformed mono-energetic electron beam is interacting with a slow-wave structure or a resonant cavity, the hybrid cavity under consideration allows for interaction of electron bunches accelerating or oscillating in a Penning trap-like static field configuration integrated with a resonant cavity, formed partially by the trap's electrodes and partially by a dielectric Bragg structure. We consider a simplified mathematical model for electron bunches formation during the field emission process under superposition of electrostatic and AC fields in the cavity. It shown that in a deep saturation regime the field-emitted current density can be approximated by a Gaussian profile. We estimate the current density spatial/temporal distribution for a train of current pulses, undergoing a single acceleration-deceleration cycle in the electrostatic field, interacting with the fundamental eigenmode of the cavity.