Novel compact and lightweight coaxial C-band transit-time oscillator*

Abstract

Compactness and miniaturization have become increasingly important in the development of high-power microwave devices. Based on this rising demand, a novel C-band coaxial transit-time oscillator (TTO) with a low external guiding magnetic field is proposed and analyzed. The proposed device has the following advantages: simple structure, short axial length, high power conversion efficiency, and low external guiding magnetic field, which are of great significance for developing the compact and miniaturized high-power microwave devices. The application of a shorter axial length is made possible by the use of a transit radiation mechanism. Also, loading the opening foil symmetrically to both ends of the buncher helps reduce the external magnetic field of the proposed device. Unlike traditional foils, the proposed opening foil has a circular-hole; therefore, the electron beam will not bombard the conductive foil to generate plasma. This makes it possible to realize long pulse and high repetition rate operation of the device in future experiments. Through numerical calculation and PIC particle simulation, the stability of the intense relativistic electron beam (IREB) and the saturation time of the device are improved by using the conductive foil. The voltage and current of the diode are 548 kV and 11.4 kA, respectively. Under a 0.4-T external guiding magnetic field, a C-band output microwave with a frequency of 4.27 GHz and power of 1.88 GW can be generated. The power conversion efficiency of the proposed device is about 30%.

Improved Power Capacity in a Low-Magnetic Field and High-Efficiency Transit-Time Oscillator by a Double-Gap Extractor

“…According to the theory in Reference [17], the transverse kinetic energy of electrons is increased by strong traveling wave fields under a low magnetic field, which is detrimental to the high beam-wave conversion efficiency. Therefore, low-magnetic field and high-efficiency HPM sources usually extract the energy of electron beams by standing wave fields, which is regarded as transit radiation [6], [18], [19], [20], [21]. To achieve efficient beam-wave interaction under a low magnetic field, concentrated energy extraction of electrons is usually adopted in transit radiation devices.…”

Experimental research based on a C-band compact transit-time oscillator with a novel diode loading an embedded soft magnetic material and shielding structure

“…In a previous study, we proposed a C-band coaxial TTO capable of operating under low magnetic field conditions. In 075201-2 the simulation study, [26] when the external guiding magnetic field was 0.4 T, with a diode voltage of 548 kV and a current of 11.4 kA, an HPM output of 1.88 GW was generated and the microwave frequency was 4.27 GHz. The beam conversion efficiency was calculated as about 30%.…”

“…Previously, our research group proposed a novel C-band TTO in simulation studies. [26] The design purpose of this device was to obtain a lightweight and compact HPM device, so we chose a low external guiding magnetic field. In the previous study, this device showed its advantages in reducing the external magnetic field.…”