Interaction Mechanism of a Field Emission Based Terahertz Generator

Summary form only given. The interactions between the electrons and the terahertz waves in a field emission based terahertz generator have been studied by employing the finite-difference time-domain particle-in-cell simulations. The cathode has been trimmed to emit electrons to understand the interaction mechanism. Simulation results show that the efficiency of the case corresponding to the trimmed cathode is up to 4% and higher than that of the original planar cathode. This indicates that the interaction mechanism is strongly related to the gaps between the cathode and the anode. The AC electric fields of the THz waves not only velocity-modulate the electron beam but also cause the density modulation of the field emission current. The inertial bunching and pre-bunching effects provide the feedback loop as required by an oscillator.