A 57GHz overmoded coaxial relativistic backward wave oscillator with high conversion efficiency and pure TM01 mode output

Siyao Chen,Zhen Bai,Jun Zhang

doi:10.1063/1.5003341

Siyao Chen, Zhen Bai + Show 1 more

Open Access

https://doi.org/10.1063/1.5003341

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Journal: AIP Advances	Publication Date: Oct 1, 2017
Citations: 9	License type: cc-by

Affiliation: National University of Defense Technology

Abstract

A 57GHz overmoded relativistic backward wave oscillator (RBWO) operating on the quasi-TEM mode with pure TM01 mode output is presented in this paper, by using outer trapezoidal slow wave structure (SWS) with large distance between inner and outer conductors. The large overmoded ratio can be obtained in coaxial devices to improve power handling capacity, while the large distance between inner and outer conductors can guarantee the electron beam transmit effectively. The 8π/9 mode of quasi-TEM synchronously interacts with the electron beam, while the TM01 mode diffracted by the quasi-TEM mode outputs. The existence of TM01 6π/9 mode in SWS can extract energy from the quasi-TEM mode (which has a high value of Qe) thus increasing the power handling capacity. Particle-in-cell simulation shows that generation with high power 560 MW and efficiency 43.5% is obtained under the diode voltage 520 kV and current 2.47 kA. And the microwave has the pure frequency spectrum of 56.8 GHz radiates in the pure TM01 mode (about 98%).

Highlights

As the millimeter-wave high power microwave (HPM) technology has matured gradually, the development of HPM generators towards higher frequency is an important trend
The analysis and design method of the support posts in coaxial extractor of HPM source are mature through the field matching theorem,[7] the coaxial devices are widely used in HPM generators
The microwave propagate in TM01 transverse mode in the output waveguide, and the longitudinal mode distribution presents the pattern of 6π/9 mode in SWS2

Summary

Introduction

As the millimeter-wave high power microwave (HPM) technology has matured gradually, the development of HPM generators towards higher frequency is an important trend. In the HPM generators, the cathode guns generally use the field explosive emission to generate nanosecond pulses, which makes the thickness of electron beam at least 1 mm. Such a narrow transmission channel will make it difficult to transmit the electron beam in the SWSs. such a narrow transmission channel will make it difficult to transmit the electron beam in the SWSs Such as the 96.2GHz coaxial BWO proposed by Ref. 10, the distance between inner and

Results

Discussion

Conclusion