A Ku-band coaxial transit-time oscillator with Pierce-like cathode under permanent magnet packaging

Haojia Chen,Baoliang Qian,Junpu Ling

doi:10.1063/1.5052557

Haojia Chen, Baoliang Qian + Show 1 more

Open Access

https://doi.org/10.1063/1.5052557

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Journal: AIP Advances	Publication Date: Nov 1, 2018
Citations: 1	License type: cc-by

Affiliation: National University of Defense Technology

Abstract

A novel Ku-band coaxial transit-time oscillator (TTO) with Pierce-like cathode is proposed in this paper. TTO has the characteristics of low space-charge effect and short interaction distance. Combining with these features, we design a novel Pierce-like cathode to lower the demand for the guiding magnetic field. The guiding magnetic field intensity is reduced to about 0.32T by loading the Pierce-like cathode, but the magnetic field intensity is not a stable value, it fluctuates at 0.32T because of the properties of permanent magnet. To achieve the light and small goals of TTO, we design a novel permanent magnet structure with NdFeB. Based on the research, the typical simulation result is that when the diode voltage is 440kV, the beam current is 11kA, the guiding magnetic field is about 0.32T, the device can output 1.46GW microwave pulse at 14.2GHz. The power conversion efficiency is about 30%.

Highlights

Transit-time oscillator (TTO) is one of the high power microwave (HPM) devices which has the advantages of high output power, single output mode, high stability and compact structure compare with the conventional relativistic HPM devices
The efficiency increases to 20% with the name split-cavity oscillator (SCO) by the effort of scientists in Sandia National Laboratories
TTO needs the guiding magnetic field to guide the transmission of the intense relativistic electron beam (IREB).[6,7,8]

Summary

INTRODUCTION

With the development of high power microwave (HPM) technology, HPM devices have achieved power levels in excess of GW in a number of cases.[1,2] Transit-time oscillator (TTO) is one of the HPM devices which has the advantages of high output power, single output mode, high stability and compact structure compare with the conventional relativistic HPM devices. The development of TTO toward to the direction of high power, high efficiency, long pulse and low guiding magnetic field intensity. TTO needs the guiding magnetic field to guide the transmission of the intense relativistic electron beam (IREB).[6,7,8] In most cases, the guiding magnetic field is generated by solenoid coils which need power supply and refrigeration system. The devices can not work efficiently when the guiding magnetic field intensity is reduced to a rather low value because of the large radial fluctuation of the IERB. We investigate how to reduce the amplitude of magnetic field to insure the transmission of the IERB.[15,16] the theoretical analysis of the IERB in coaxial drift-tube can provide some ideas. I 2π en[0] rb v0 is the thickness of annular electron beam, rb center in the balance position of the IERB, v0 is the speed of electronic near the cathode

And the value of lowest guiding magnetic field can be obtained

THE DESIGN OF PERMANENT GUIDING SYSTEM

SIMULATION RESULTS AND ANALYSIS

CONCLUSION