Starting current of coaxial relative backward wave oscillator

Teng, Yan; Xiao, Renzhen; Liu, Guozhi; Chen, Changhua; Shao, Hongxia; Tang, Chuanxiang

doi:10.1063/1.3447884

Cited by 16 publications

(7 citation statements)

References 18 publications

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“…This is tentatively considered to be because of the merits of the quasi-resonating cavity. 4,9 It is shown in Fig. 19 that the application of the coaxial dual annular cathodes greatly reduces the diode impedance.…”

Section: Numerical Analysis and Resultsmentioning

confidence: 99%

“…However, in the coaxial SWS, both the fundamental and the -1st harmonic branches of the quasi-TEM mode lie in the slow-wave region. 9 Thus, an electron beam with kinetic energy that is too high will deviate seriously from the π point of the quasi-TEM mode, as shown in Fig. 4, which indicates that the electron beams with energies of 700 keV and 800 keV are apparently far from the π point.…”

Section: A Dispersion Relationmentioning

confidence: 98%

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Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

et al. 2013

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This paper presents an approach that greatly enhances both the output power and the conversion efficiency of the coaxial relativistic backward wave oscillator (CRBWO) by using coaxial dual annular cathodes, which increases the diode current rather than the diode voltage. The reasons for the maladjustment of CRBWO under a high diode voltage are analyzed theoretically. It is found that by optimization of the diode structure, the shielding effect of the space charge of the outer beams on the inner cathode can be alleviated effectively and dual annular beams with the same kinetic energy can be explosively emitted in parallel. The coaxial reflector can enhance the conversion efficiency by improving the premodulation of the beams. The electron dump on the inner conductor ensures that the electron beams continue to provide kinetic energy to the microwave output until they vanish. Particle-in-cell (PIC) simulation results show that generation can be enhanced up to an output power level of 3.63 GW and conversion efficiency of 45% at 8.97 GHz under a diode voltage of 659 kV and current of 12.27 kA. The conversion efficiency remains above 40% and the output frequency variation is less than 100 MHz over a voltage range of more than 150 kV. Also, the application of the coaxial dual annular cathodes means that the diode impedance is matched to that of the transmission line of the accelerators. This impedance matching can effectively eliminate power reflection at the diode, and thus increase the energy efficiency of the entire system

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Section: Numerical Analysis and Resultsmentioning

confidence: 99%

Section: A Dispersion Relationmentioning

confidence: 98%

Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

et al. 2013

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“…Therefore, it is suggested that the resonant reflector with low external quality factor Q (≤10) should be chosen to minimize the unavoidable increase of electric field in the reflector region (Gunin et al, 1998a). In the hot dispersion shown in Figure 12, the structure wave and the slower space charge wave merge into a complex conjugate pair of solution whose imaginary part represents the temporal growth rate in the range of β 0 p from 0 to π (Teng et al, 2010). The ripple period and the ripple depth are p = 16 mm and d = 2 mm, respectively.…”

Section: Application Of Resonant Reflectormentioning

confidence: 99%

Design and efficient operation of a coaxial RBWO

et al. 2013

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Coaxial relativistic backward wave oscillator with the rippled inner conductor not only increases the output efficiency but also results in the serious phenomenon of pulse shortening in experiments. Our research indicates that the two main mechanisms leading to the pulse shortening are the electron beam interruption and combining effects of the explosive field electron emission and the secondary electron multipactor on the surface of the slow-wave structure. In order to enhance its power capacity the electrodynamic structure is modified by detailed analysis of the field distribution in the coaxial slow-wave structure. The appropriate resonant reflector and the electron collector are developed for the application of the coaxial relativistic backward wave oscillator. A series of surface treatment is applied to enhance the power capacity of the coaxial RBWO. In the experiment, the microwave pulse duration is increased from less than 10 ns to 20 ns, and the output efficiency is enhanced from less than 20% to 34% employing the electron beam pulse of the full width at half maximum 28 ns. The peak power of 1.01 GW at the frequency of 7.4 GHz is achieved. It is found that the output efficiency of the coaxial RBWO is likely to be advanced if its power capacity can be boosted further.

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“…10 The mode competition unfavorably affects the wavebeam interaction and results in the generation with the impure spectrum consisting of several frequency components. 11 Furthermore, the generated power in the overmoded SWS always partly leaks into the diode region. This disturbs the explosive emission and the transmission of the electron beam.…”

Section: Introductionmentioning

confidence: 99%

A Ka-band TM02 mode relativistic backward wave oscillator with cascaded resonators

et al. 2014

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By combining the Cerenkov-type generator with the cascaded resonators, this paper proposes a Ka-band relativistic backward wave oscillator operating under the guide magnetic field 1.0 T with high power handling capability and high conversion efficiency. It is found that TM 02 can be selected as the operation mode in order to increase the power handling capability and provide sufficient coupling with the electron beam. In slow wave structure (SWS), ripples composed of semicircle on top of the rectangle enhance the wave-beam interaction and decrease the intensity of the electric field on the metallic surface. Taking advantage of the resonator cascades, the output power and the conversion efficiency are promoted greatly. The front cascaded resonators efficiently prevent the power generated in SWS from leaking into the diode region, and quicken the startup of the oscillation due to the premodulation of the beam. However, the post cascade slightly postpones the startup because of the further energy extraction from the electron beam. The numerical simulation shows that generation with power 514 MW and efficiency 41% is obtained under the diode voltage 520 kV and current 2.4 kA. And the microwave with the pure frequency spectrum of 29.35 GHz radiates in the pure TM 01 mode. V C 2014 AIP Publishing LLC.

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Starting current of coaxial relative backward wave oscillator

Cited by 16 publications

References 18 publications

Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

Design and efficient operation of a coaxial RBWO

A Ka-band TM02 mode relativistic backward wave oscillator with cascaded resonators

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