A double-beam magnetron-injection gun for third-harmonic continuous wave 1-THz gyrotron

摘要

The concept of a continuous wave 1-kW/1-THz gyrotron operated at the third cyclotron harmonic of the transverse electric TE_(9,7) operating mode has been developed. To suppress the mode competition effects in a terahertz gyrotron, we propose a scheme with two generating helical electron beams (HEBs) formed in a double-beam triode magnetron-injection gun (MIG), where both emitters of the electron beams are located on a common cathode of the conventional MIG. An optimal geometry of the MIG electrodes is found. It is shown that in a proposed scheme two HEBs having close pitch factors and a moderate velocity spread can be formed. This makes them suitable for high-efficiency single-mode generation in the high frequency gyrotron at high harmonic.