| A field-emission triode was designed, simulated, and assembled using a single 3.8mm diameter Ar+-ion irradiated reticulated vitreous carbon (RVC) cathode. The irradiation process results in random carbon nano-structures on the surface of the RVC, providing effective, low-field emission sites. The grid electrode further increases local field enhancement on the cathode's surface, increasing the extracted current and decreasing the turn on voltage, when compared to diode mode characteristics. The anode electric field required to produce 0.1muA/cm2 was measured to decrease from 0.9 V/mum to 0.65V/mum with 300V applied to the grid electrode. With 2.1V/mum, and 300V applied to the grid, the limits of our power supply, a current density of 16.0mA/cm2, and a current of 1.82mA from a single cathode was measured. Simulations were conducted to examine isopotentials and the modified electric field due to a potential on the grid electrode. Semiconductor-like emission properties, showing three regions of operation, were observed. In region III the cathode emits from a large number of sites. Hysteresis due to a drop in conductivity that could be attributed to local heating of the cathode was also obs. |
