An advanced terahertz EIO operating with TM31 mode

In order to increase the feasibility and reliability of the terahertz extended interaction oscillator (EIO), the method of adopting TM31 in the reentry cavity is proposed. The characteristics of high-order EIO is theoretically analyzed, including its electromagnetic properties and the field distributions in it. Compared with the traditional EIOs those operating at the fundamental mode, the advantages of higher power capability and less difficulty in fabrication for the high-order EIOs are proved. Then the structure of high-order EIO is optimized and the performance is studied by the particle-in-cell (PIC) simulations. Under the conditions of 15kV and 150mA for the electron beam, the output power reaches about 85W, corresponding to the efficiency of 3.7% The frequency is 338.4GHz and the operating mode is verified as TM31 mode, which is stable.