Low-Voltage Operation of the Double-Beam Gyrotron at 400 GHz

For the double-beam THz gyrotron, an efficient operation under nonrelativistic acceleration voltages is experimentally demonstrated. The output power at the frequency of 0.4 THz was 60 W for an operating voltage of 5.4 kV, and the starting voltage was as low as 2.4 kV; that is in good agreement with calculations. The starting voltage can be further decreased, and the output power can be increased by increasing the beam pitch factor at low voltages. Simulations of three-electrode magnetron injection gun (MIG) show that it can be achieved by the optimized MIG geometry and by applying the positive voltage at the modulating anode.