Abstract
In order to improve the beam–wave interaction efficiency, a special circle-sector-shaped electron beam is designed and simulated in the confocal waveguide gyrotron traveling-wave tube (gyro-TWT). The linear and nonlinear characteristics of a 0.22 THz multistage confocal waveguide gyro-TWT are analyzed. Based on kinetic theory, the linear gain, critical current of absolute instability, and starting current of backward wave oscillation (BWO) are analyzed. A quasi-optical sever is utilized in the confocal waveguide to suppress the BWO while having a slight impact on the output power. Meanwhile, the impact of velocity spread on the output parameters is also taken into consideration. The nonlinear analyses indicate that the efficiency can be up to 34%, which is substantially higher than the traditional annular electron beam.
Highlights
Terahertz (THz) technology has great potential for applications in high-resolution radar, communications, medicine, and physics.1–4 Based on the electron cyclotron maser (ECM), the gyrotron traveling-wave tube is one of the most potential radiation sources for high power in the low frequency THz band
Some progress has been made in a Ka band gyro-traveling-wave tube (TWT) experiment, operating in the TE11 mode in the distributed loss loaded interaction structure, and a saturated output power of 137 kW was obtained, with a gain of 47 dB, an efficiency of 17%, and a 3-dB bandwidth of 1.11 GHz
From Eqs. (8)–(16), we present a set of self-consistent nonlinear theory equations of a confocal waveguide gyro-TWT
Summary
Terahertz (THz) technology has great potential for applications in high-resolution radar, communications, medicine, and physics. Based on the electron cyclotron maser (ECM), the gyrotron traveling-wave tube (gyro-TWT) is one of the most potential radiation sources for high power in the low frequency THz band. Based on the electron cyclotron maser (ECM), the gyrotron traveling-wave tube (gyro-TWT) is one of the most potential radiation sources for high power in the low frequency THz band. Some progress has been made in a Ka band gyro-TWT experiment, operating in the TE11 mode in the distributed loss loaded interaction structure, and a saturated output power of 137 kW was obtained, with a gain of 47 dB, an efficiency of 17%, and a 3-dB bandwidth of 1.11 GHz.. As the frequency toward the THz band, the main problems faced by the gyro-TWT are the reduction of the interaction structure and the increase of the Ohmic loss due to operating in fundamental or lower-order modes that can reduce the mode competition.. Previous studies on the confocal waveguide gyro-TWT with an annular electron beam have obtained low efficiency..
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