Influences of the Modulation Cavity and Extraction Cavity on Microwave Generation and Starting Oscillation in a Klystron-Like Relativistic Backward Wave Oscillator

Xiao, Renzhen; Chen, Changhua; Tan, Weibing; Teng, Yan

doi:10.1109/ted.2013.2295380

Cited by 24 publications

(8 citation statements)

References 16 publications

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“…Besides optimizing the SWS to increase the reflection coefficient for TM 01 mode, the adoption of reflector is also useful to enhance the strength of TM 01 mode in the SWS [43][44][45][46] . As mentioned in Section I, the power going back to the diode area is harmful to the cathode and decreases the device's efficiency 48,49 .…”

Section: Design Of the Dual-reflectormentioning

confidence: 99%

“…Although the oversized slow wave devices are competitive in generating the high power terahertz waves, the generation efficiency is still very low. According to the practices for enhancing the generation efficiency of the high power microwave sources, some methods are very efficient, such as the non-uniform SWS, klystron-like structure, and resonant reflector, etc [40][41][42][43][44][45][46] . Nevertheless, not all of these methods are practicable in the terahertz SWO devices.…”

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confidence: 99%

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Relativistic Surface Wave Oscillator in Y-Band with Large Oversized Structures Modulated by Dual Reflectors

Wang

2020

Sci Rep

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To increase the generation efficiency of the terahertz wave in the Y band, the idea of dual-reflector is introduced in the relativistic surface wave oscillator (SWo) with large oversized structures. the dual-reflector and the slow-wave structure (SWS) construct a resonator where the field strength of tM 01 mode inside is intensively enhanced and then the efficiency is increased. The pre-modulation on electron beam caused by the reflector is also helpful in improving the output power. Meanwhile, the reflector can reduce the loss of negatively going electrons. Through the particle-in-cell (PIC) simulations, the optimized structure is tested to be stable and little power is transmitting back to the diode area. The output power reaches 138 MW in the perfectly electrical conductivity condition and the frequency is 337.7 GHz with a pure spectrum. The device's efficiency is increased from 10.7% to 16.2%, compared with the device without any reflectors. The performance of device with lossy material is also focused on. In the situation of copper device, the output power is about 41 MW under the same input conditions and the corresponding efficiency is about 4.8%. In recent years, the terahertz wave has shown great potential in the applications of remote high-resolution imaging, remote detection of radioactive material, deep space research and communications, plasma diagnostic in nuclear fusion, materials research, biomedical diagnostics, high data rate communications, basic biological spectroscopy, chemical spectroscopy, and so on 1-8. The prospect of terahertz technology has attracted many researchers to devote to developing the high power terahertz generators, especially the vacuum electronic devices (VEDs) 9-13. And the slow wave devices are an important class of the VEDs. Based on the interaction between the intense electron beam and the slow-wave structure (SWS), the backward wave oscillator (BWO) becomes a remarkable kind of slow wave device with good performance in high output power and compact structure 14,15. In a BWO, the electrons are in synchronism with −1 st spatial harmonic wave. When a slow wave device operates near the upper edge of the transmission band, it becomes a surface wave oscillator (SWO) whose operation point is close to π point. In an SWO, the fundamental wave slows down to the electron velocity 16. The Q-factor in the SWO is relatively large due to the large reflection and small group velocity, and then the start current is usually lowered in this case 17,18. What's more, the large coupling impedance in the SWO is significant in obtaining high interaction efficiency. Besides, use of the surface wave is valid in achieving mode selection in the overmoded structure as well. Thus, the SWO attracts more and more attention in generating millimeter and terahertz waves. However, their structural dimensions decrease rapidly as the working frequency goes up, causing many crucial problems that must be solved, such as the internal breakdown, limitation of the power capacity, and difficulties in manufacturi...

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Section: Design Of the Dual-reflectormentioning

confidence: 99%

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confidence: 99%

Relativistic Surface Wave Oscillator in Y-Band with Large Oversized Structures Modulated by Dual Reflectors

Wang

2020

Sci Rep

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“…When port 4(3) is incident with the TE 11 mode polarized along y-axis, the inserted metal plates are similarly orthogonal to the E-field of the transmitting mode. The transmitting mode will propagate through the PIS and output at port 3 (4). When the port 3 is incident with the TE 11 mode polarized along x-axis, the inserted metal plates are parallel to the E-field of the receiving mode.…”

Section: Design Of the Trsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9] Various microwave generation and transmitting devices are combined and working for the directional microwave systems. However, these systems can only work at the transmitting format.…”

Section: Introductionmentioning

confidence: 99%

A transmitting and receiving structure for high power applications

Guo

Huang

et al. 2017

AIP Advances

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A high-power-capacity transmitting and receiving structure (TRS) is proposed. It has the ability of transmitting the GW-level high power microwave from the microwave sources with the horizontal polarized TE11 mode and receiving the microwave signal from the target with the orthogonal polarized TE11 mode. It is realized by the cooperation of a polarization-isolation-structure (PIS) and a two-way circular TE11 mode to rectangular TE10 mode power divider. Simulation shows that from 9.65 to 9.71 GHz, its power capacity is more than 3 GW at the transmitting format. The transmitting and receiving channel have an isolation of 60 dB which can prevent the receivers connecting to the receiving channel suffering from breakdown. The insertion losses for the transmitting and receiving format are both less than 0.03 dB.

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“…By using non-uniform slow wave structures (SWSs), conversion efficiency of RBWO-RR exceeds 30% in X-band [6]. Xiao et al proposed klystron-like RBWO (KL-RBWO) by introducing modulation cavity and extraction cavity based on RBWO-RR, significantly improving the efficiency to 50% by combining transition radiation and Cerenkov radiation [9][10][11][12]. Then the highest efficiencies over 70% have been demonstrated in particle-in-cell (PIC) simulations of KL-RBWO with numerous and complicated cavities [11].…”

Section: Introductionmentioning

confidence: 99%

Efficiency Enhancement of a Klystron-Like Relativistic Backward Wave Oscillator With Waveguide Reflection and Bunching Promotion

Wang

Xiao²,

Shi³

et al. 2020

IEEE Access

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A klystron-like relativistic backward-wave oscillator (KL-RBWO) with transverse electron beam confinement and waveguide reflection, which works well under a magnetic-field strength below that of the cyclotron resonance, is proposed. For this device operating with a low magnetic field, effective suppression of the transverse velocity of electron beams is introduced by a local electric field near the tube head, to promote modulation uniformity of electron beams. Part of the reflected microwave from the output waveguide provides feedback enhancement to the extractor, which strengthens the local standing-wave field. Owing to a stronger electric field that can interact with the electron beam in the extractor and a higher growth of fundamental harmonic current, the efficiency of the KL-RBWO is increased to 40% when guided by a magnetic field of 0.32 T, compared with that of 30% using conventional structures.INDEX TERMS High power microwaves, intense relativistic electron beams, relativistic backward-wave oscillator, Cherenkov radiation

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Influences of the Modulation Cavity and Extraction Cavity on Microwave Generation and Starting Oscillation in a Klystron-Like Relativistic Backward Wave Oscillator

Cited by 24 publications

References 16 publications

Relativistic Surface Wave Oscillator in Y-Band with Large Oversized Structures Modulated by Dual Reflectors

Relativistic Surface Wave Oscillator in Y-Band with Large Oversized Structures Modulated by Dual Reflectors

A transmitting and receiving structure for high power applications

Efficiency Enhancement of a Klystron-Like Relativistic Backward Wave Oscillator With Waveguide Reflection and Bunching Promotion

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