Efficiency enhancement of high power vacuum BWO's using nonuniform slow wave structures

Moreland, L.D.; Schamiloglu, E.; Lemke, W.; Korovin, S. D.; Rostov, V. V.; Roitman, A.; Hendricks, K.J.; Spencer, Thomas A.

doi:10.1109/27.338268

Cited by 101 publications

(27 citation statements)

References 4 publications

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“…To increase the beam-wave interaction efficiency and output power is one of the most important considerations of highpower microwave sources (Bugaev et al, 1990;Friedman & Serlin, 1992;Moreland et al, 1994;Eltchaninov et al, 2003;Korovin et al, 2003;Liu et al, 2008aLiu et al, , 2008bXiao et al, 2007Xiao et al, , 2008a. The highest power so far was achieved by the multiwave Cerenkov generator (Bugaev et al, 1990), and relativistic klystron amplifier (Friedman & Serlin, 1992;Serlin & Friedman, 1994) in the 1990s.…”

Section: Introductionmentioning

confidence: 99%

Efficient generation of multi-gigawatt power by a klystron-like relativistic backward wave oscillator

Xiao

Zhang

et al. 2010

Laser Part. Beams

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Efficient generation regime with a high power output has been experimentally realized in a klystron-like relativistic backward wave oscillator, in which a modulation cavity is inserted between the slow wave structure to decrease the energy spread of modulated beam electrons, and an extraction cavity is employed at the end of the slow wave structure to further recover energy from the electron beam. At a guiding magnetic field of 2.2 T, a microwave pulse with power of 6.5 GW, frequency of 4.26 GHz, pulse duration of 38 ns, and efficiency of 36% was generated when the diode voltage was 1.1 MV, and diode current was 16.4 kA. When the diode voltage was 820 kV, efficiency up to 47% with microwave power 4.4 GW was also realized experimentally.

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Section: Introductionmentioning

confidence: 99%

Efficient generation of multi-gigawatt power by a klystron-like relativistic backward wave oscillator

Xiao

Zhang

et al. 2010

Laser Part. Beams

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“…It is confirmed to be an effective method to adopt the improved slow wave structure (SWS) such as the nonuniform SWS [2], [3] and the sectional SWS [4]. The coaxial RBWO (CRBWO) provides a new approach [5] and the further research put forward the new type of CRBWO with the ripples on both the inner and outer conductors, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

A New Reflector Designed for Efficiency Enhancement of CRBWO

Teng

Liu

Shao

et al. 2009

IEEE Trans. Plasma Sci.

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A new reflector consisting of the inner and outer conductors is introduced into the coaxial relativistic backward wave oscillator for the first time through optimizing the distribution of the electric field and distance between the reflector and the slow wave structure. The improved reflector can excite the superposition of the axial electric fields to benefit the electron premodulation. The improved reflector is investigated by the particle-in-cell numerical simulation. A result of 43% power efficiency, 1.0-GW power, and 7.3-GHz operation frequency is obtained under the diode voltage 530 kV and current 4.4 kA.Index Terms-Coaxial relativistic backward wave oscillators (CRBWOs), high-power microwave (HPM), interaction efficiency, premodulation.

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“…The relativistic backward wave oscillator (RBWO) is one of the most promising high power microwave devices with the virtues of high power, high efficiency, and high repetition rate. [1][2][3] To increase the beam-wave interaction efficiency, some techniques are used, such as non-uniform slow wave structure (SWS), resonant reflector, and oversized structure, [4][5][6][7][8][9][10][11] etc. Compared to the conventional RBWOs, the structures of the improved devices are very complicated.…”

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confidence: 99%

Optimization of relativistic backward wave oscillator with non-uniform slow wave structure and a resonant reflector

Chen

Wang

2015

Physics of Plasmas

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This letter optimizes synchronously 18 parameters of a relativistic backward wave oscillator with non-uniform slow wave structure (SWS) and a resonant reflector by using the parallel genetic algorithms and particle-in-cell simulation. The optimization results show that the generation efficiency of microwave from the electron beam has increased 32% compared to that of the original device. After optimization, the electromagnetic mode propagating in the resonant changes from the original TM 020 mode of reflector to higher-order TM 021 mode, which has a high reflection coefficient in a broader frequency range than that of the former. The modulation of current inside the optimized device is much deeper than that in the original one. The product of the electric field and current is defined. Observing this product, it is found that the interaction of the electron beam with the electromagnetic wave in the optimized device is much stronger than that in the original device, and at the rear part of SWS of the optimized device, the electron beam dominantly gives out the energy to the electromagnetic wave, leading to the higher generation efficiency of microwave than that of the original device. V C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4906896]The relativistic backward wave oscillator (RBWO) is one of the most promising high power microwave devices with the virtues of high power, high efficiency, and high repetition rate. 1-3 To increase the beam-wave interaction efficiency, some techniques are used, such as non-uniform slow wave structure (SWS), resonant reflector, and oversized structure, 4-11 etc. Compared to the conventional RBWOs, the structures of the improved devices are very complicated. For an example, Chen et al. proposed a RBWO with non-uniform SWS and a resonant reflector, which has 18 structural parameters to be adjusted. 8 It is very difficult to adjust tens of the parameters of the structures experimentally and numerically.To tackle with this difficulty, we proposed to optimize the parameters of HPM devices by using parallel genetic algorithms and particle-in-cell simulation (PGA-PIC), 12-14 and optimized the structural parameters of a RBWO. After optimization, the beam-wave interaction efficiency of the device increased significantly.Based on a model of the RBWO with 7-periods uniform SWS and a resonant reflector, Chen et al. analyzed the effect of non-uniform SWS on the RBWO, driven by the diode voltage of 1.02 MV and beam current of 13.2 kA. 8 After adjusting the heights of the front-end 3-periods SWS and keeping the other 4-periods SWS unchanged, the output power increased to 4 GW from 3 GW of that with the uniform SWS, the microwave frequency is 9.7 GHz, and the corresponding beam-wave interaction efficiency of the device increased to 30% from 22%. For convenience of discussion, the device with non-uniform SWS, presented by Chen et al., is termed as "device A" here.To further study the beam-wave interaction efficiency of this kind of device, we use the PGA-PIC method to optimize the 18 str...

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Efficiency enhancement of high power vacuum BWO's using nonuniform slow wave structures

Cited by 101 publications

References 4 publications

Efficient generation of multi-gigawatt power by a klystron-like relativistic backward wave oscillator

Efficient generation of multi-gigawatt power by a klystron-like relativistic backward wave oscillator

A New Reflector Designed for Efficiency Enhancement of CRBWO

Optimization of relativistic backward wave oscillator with non-uniform slow wave structure and a resonant reflector

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