Study On Terahertz Electron Cyclotron Maser Devices

Terahertz (THz) wave, electromagnetic radiation between far infrared and millimeter wave, has very important academic and application value. Electron Cyclotron Maser (ECM) is an important terahertz radiation source, which has high output power and high efficiency, and considered to generate highest output power in terahertz spectrum. It has widely potential applications including THz radar, THz imaging, THz communication, plasma heating and so on. The THz ECM devices have been investigated in many countries, such as United States, Russia, Germany and Japan. However, it is a vacuum research area in our country. In this thesis, the THz ECM devices have been investigated, and the main work included:1. Investigated the Electron Optics System for ECM devices. Designed a 8 Tesla pulse magnet and an electron gun for 0.22THz/30kV gyrotron. The experiments show that the peak pulse field of the magnet could higher than 8 Tesla, and the electron gun could generate 1.15mm radius ring electron beam; Designed an electron gun for 0.22THz/60kV gyrotron based on 9.2 Tesla superconducting magnet; Proposed two types two-beam magnetron injection gun for coaxial gyrotron with two beams (CGTB): Normal Two-Beam Magnetron Injection Gun (NTBMIG) and Coaxial Two-Beam Magnetron Injection Gun (CTBMIG). Simulations show both of them could satisfied the requirement of CGTB.2. Investigated the terahertz gyromonotron. Based on the linear theory and nonlinear theory of ECM, a 0.22THz/30kV gyromonotron, a 0.22THz/60kV gyromonotron and a second harmonic gyromonostron have been designed.3. Investigated the terahertz gyro-backward-wave-oscillator (gyro-BWO). Designed a TE03 mode backward output type gyro-BWO and a forward output type gyro-BWO. Simulations show that both of them could generate kW level tunable output while bandwidth wider than 1GHz. The interaction efficiency of backward output type gyro-BWO is bigger than that of forward output type gyro-BWO, while the structure of forward output type gyro-BWO is more compact.4. In order to investigated the novel interaction mechanism of gyro-amplifier and reduce the operation magnet, the harmonic gyro-klystron has been theoretical studied, especially the optimization. Numerical analysis show that The numerical results show that the perpendicular efficiencies higher than 55%, 40%, 30%, and 15% are found for the fundamental, second, third, and fourth harmonics, respectively, when operating in amplifier region; and the perpendicular efficiencies as high as 93.9%, 88.2%, 81.8%, and 62.7% are found for the fundamental, second, third, and fourth harmonics, respectively, when operating in oscillator region.5. Participated in the experiments of 0.22THz/30kV gyrotron with pulse magnet and 0.22THz/60kV gyrotron with superconducting magnet. The output power of 0.22THz/30kV gyrotron with pulse magnet has been achieved 11.5kW, and the frequency is between 0.22THz and 0.234THz. The output power of 0.22THz/60kV gyrotron with superconducting magnet has been achieved 26.5kW, and the frequency is 0.2281THz. Further studies show, through adjusting operation voltage and magnet, the 0.22THz/60kV gyrotron with superconducting magnet generated 4.4kW, about 0.423THz second harmonic output. This is highest frequency terahertz radiation record of vacuum electron devices in China.