A High-Current-Density Terahertz Electron-Optical System Based on Carbon Nanotube Cold Cathode

A high-current-density terahertz electron-optical system based on a carbon nanotube (CNT) cold cathode has been investigated in order to solve notable mode competition in high-order harmonic gyrotrons. Simulation results show that a near-axis electron beam can be generated, with a beam current of 160 mA at an accelerating voltage of 23.5 kV. The source supports the electron beam with a velocity ratio of 1.1 and a guiding center radius of $57~\mu \text{m}$ . A narrow beam spatial distribution is evidenced by adjusting control anode voltage, satisfying the need for high operating current density in slow wave devices. The current density of the electron beam is up to 620 A/cm2 at the output port and the velocity ratio is 0.44, with parallel energy accounting for 84% of the total energy.