Improved Performance of Oversized Backward Wave Oscillator Driven by Weakly Relativistic Electron Beam

Aoyama, Satoshi; Miyazawa, Yushi; Ogura, K.; Sugawara, Akira; Hirata, M.

doi:10.13182/fst07-a1390

Cited by 23 publications

(29 citation statements)

References 1 publication

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“…[1], and their improved performance has been reported in Ref. [2]. In these previous experiments, hollow SWSs were used, and manufacturing of the periodical corrugation became difficult as the operating frequency increased.…”

Section: Introductionmentioning

confidence: 84%

“…In slowwave devices, slow-wave structure (SWS) is used to reduce the phase velocity of electromagnetic waves to the beam velocity. To increase the operating frequency and powerhandling capability, oversized devices have been used successfully [1,2]. The term "oversized" means that the diameter D of the SWS is larger than the free-space wavelength λ of the output electromagnetic waves by at least several times.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study of Oversized Backward Wave Oscillator with Coaxial Slow-Wave Structure

Yoshimura

Ogura

Bansho

et al. 2010

Plasma and Fusion Research

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Studies of coaxial oversized backward wave oscillators (BWOs) are reported. The beam voltage is weakly relativistic (less than 100 kV). The slow-wave structure consists of a periodically corrugated oversized waveguide and periodically corrugated inner conductor, whose target operating frequency due to Cherenkov interaction is in the K-band. A starting energy exists for the coaxial oversized BWO as it does for a hollow oversized BWO. The coaxial slow-wave structure has two surface wave modes caused by the inner and outer corrugations. Operation based on these surface modes can be controlled by the beam diameter. The phase difference between the inner and outer corrugations has little effect on operation of the oversized BWO.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Experimental Study of Oversized Backward Wave Oscillator with Coaxial Slow-Wave Structure

Yoshimura

Ogura

Bansho

et al. 2010

Plasma and Fusion Research

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“…Smith-Purcell free electron lasers (SP-FELs) [1][2][3] and backward wave oscillators (BWOs) [4][5][6] have been studied extensively to obtain high frequency and high power electromagnetic (EM) waves. In SP-FELs, electron beams pass near the grating and excite some of the spatial harmonics of grating leading to SP radiations [1].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, performance of the weakly relativistic oversized BWO has been improved by using uniformly distributed annular electron beam of current on the order of 100 A. The radiation powers are about 500 kW (K-band) and about 200 kW (Q-band) [6]. The values of D/λ are about 2.5 for K-band and about 4.2 for Q-band.…”

Section: Introductionmentioning

confidence: 99%

“…For example, a magnetic field less than 1.0 T is used to guide an annular electron beam in the weakly relativistic oversized BWOs [6] and a magnetic field around 0.4 T was necessary for a ribbon-like beam focusing of Ledatron and SP-FEL [7,9]. The three-dimensional (3D) beam perturbations lead to the slow cyclotron interaction as well as the Cherenkov interaction [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Surface Waves in Oversized G-Band Slow-Wave Structures with Rectangular Corrugations

Ogura

Kojima

Kawabe

et al. 2014

Plasma and Fusion Research

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Surface waves in oversized G-band slow-wave structure with rectangularly corrugated wall are analyzed numerically. The inner corrugation generates cylindrical surface wave. The outer corrugation also generates transverse magnetic surface wave. The upper cut-offs of surface waves are controlled by corrugation amplitude. In excitation of the surface waves by an annular electron beam, the slow cyclotron interaction as well as the Cherenkov interaction occur due to there-dimensional beam perturbations. The slow cyclotron interaction merges with the Cherenkov interaction at lower magnetic field. The merged growth rate is enhanced by 13 % as compared to the isolated Cherenkov growth rate. The surface waves on inner and outer corrugations can have different frequencies and can be excited selectively by adjusting the beam radius of the electron beam.

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Numerical investigations on the effects of geometrical parameters on free electron laser instability

Sharma

Jaiman

2008

J. Plasma Phys.

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In this paper we numerically investigate the effects of various geometrical parameters of a backward wave oscillator (BWO), filled with a magnetized plasma of uniform density and driven by a mild relativistic solid electron beam, on the instability growth rate (Γ) of a free electron laser (FEL). The FEL instability is numerically calculated and the result is compared with the instability growth rate of an annular electron beam for the same set of parameters. The instability growth for a solid electron beam scales inversely to the seventh power of relativistic gamma factor γ0 and directly proportional to the corrugation amplitude.

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Improved Performance of Oversized Backward Wave Oscillator Driven by Weakly Relativistic Electron Beam

Cited by 23 publications

References 1 publication

Experimental Study of Oversized Backward Wave Oscillator with Coaxial Slow-Wave Structure

Experimental Study of Oversized Backward Wave Oscillator with Coaxial Slow-Wave Structure

Surface Waves in Oversized G-Band Slow-Wave Structures with Rectangular Corrugations

Numerical investigations on the effects of geometrical parameters on free electron laser instability

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