High Power Laser and Particle Beams, Volume. 37, Issue 7, 073001(2025)
Design of X-band coaxial gyrotron cavity driven by intense relativistic electron beam
Under the driving of explosive-emission cathodes, relativistic gyrotrons frequently suffer from virtual cathode phenomena induced by ultrahigh beam currents (>300 A), where electron beams readily impact the inner conductor surfaces, accompanied by unintended excitations of cyclotron resonance and backward-wave oscillation (BWO) modes. This study systematically investigates the electromagnetic characteristics of an X-band coaxial gyrotron cavity driven by an intense relativistic electron beam (IREB), combining theoretical analysis with three-dimensional particle-in-cell (PIC) simulations. The results demonstrate that stable IREB transmission and TE01 single-mode operation can be achieved through cavity geometry optimization and electron beam parameter matching. The cavity quality factor (Qcav) plays a critical role in suppressing parasitic mode competition: TE21-BWO modes are excited when Qcav<65, while TE31 cyclotron resonance modes emerge when Qcav>90. Stable TE01 single-mode oscillation with an output power of 35 MW (voltage: 300 kV, current: 500 A, transverse-to-longitudinal velocity ratio: 1.2) and efficiency of 34.4% are maintained within the Qcav range of 65-90. Further studies reveal that the cavity exhibits significant robustness against electron beam velocity spread (Δβ<25%), providing critical insights for high-power microwave source design.
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Chenxiang An, Ning Zhou, Kun Chen, Dengpan Wang, Chong Li, Youyou Gui, Yihang Yang, Xinhong Cui, Yanchao Shi. Design of X-band coaxial gyrotron cavity driven by intense relativistic electron beam[J]. High Power Laser and Particle Beams, 2025, 37(7): 073001
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Received: Mar. 8, 2025
Accepted: Jun. 1, 2025
Published Online: Jul. 18, 2025
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