Self-consistent linear analysis of slow cyclotron and Cherenkov instabilities

Watanabe, Osamu; Ogura, K.; Cho, T.; Amin, Md. Ruhul

doi:10.1103/physreve.63.056503

Cited by 31 publications

(25 citation statements)

References 16 publications

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“…Fig. 5, CSW growth rate is a merged one of the Cherenkov and slow cyclotron growth rates, which is called "merged growth rate" [12]. The Cherenkov and slow cyclotron growth rates exist separately with a sufficiently strong B 0 and merge around B 0 = 0.4 T as shown in Fig.…”

Section: Numerical Resultsmentioning

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]. The slow cyclotron interaction is caused by the anomalous Doppler effect and essentially different from the fast cyclotron interaction, which is due to the normal Doppler effect.…”

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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Section: Numerical Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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“…At the beam surface (r = R a + Δ p /2 or r = R a − Δ p /2), the following four independent equations are obtained in accordance with the methods presented in Refs. [3,4].…”

Section: Discussionmentioning

confidence: 99%

“…For the solid beam, the derivation of dispersion relation is provided in Refs. [3,4]. The solid beam has one surface.…”

Section: Methodsmentioning

confidence: 99%

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Instability Driven by a Finitely Thick Annular Beam in a Dielectric-Loaded Cylindrical Waveguide

Tamura

Yamakawa

Takashima

et al. 2008

Plasma and Fusion Research

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The cherenkov and slow cyclotron instabilities driven by an axially injected electron beam in a cylindrical waveguide are studied using a new version of the self-consistent linear theory considering three-dimensional beam perturbations. There are three kinds of models for beam instability analysis, which are based on a cylindrical solid beam, an infinitesimally thin annular beam, and a finitely thick annular beam. Among these models, the beam shape properly representing the often used actual annular electron beams is the finitely thick annulus. We develop a numerical code for a cylindrical waveguide with a finitely thick annular beam. Our theory is valid for any beam velocity. We present eigen-modes of the cylindrical system with the plasma and beam. Instabilities driven by the annular beam in a dielectric-loaded waveguide are also examined.

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Slow cyclotron instability due to surface modulation of an annular beam

et al. 2006

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The Cherenkov instability used in slow-wave devices has been well studied in the literature. However, in previous analyses, the beam motion is restricted to the longitudinal direction assuming an infinitely strong magnetic field. For the finite strength magnetic field, the transverse beam perturbation cannot be ignored and leads to the slow cyclotron instability. Recently, a new version of self-consistent field theory considering three-dimensional perturbation has been developed based on a solid beam, in which the effect of the transverse perturbation appears as a surface charge at a fixed boundary. In the case of a thin annular beam, the boundary is modulated and is essentially different from the solid beam case. We propose a self-consistent field theory considering the moving modified boundary surface. The slow cyclotron instability due to the modulation of an infinitesimally thin annular electron beam is presented.

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Self-consistent linear analysis of slow cyclotron and Cherenkov instabilities

Cited by 31 publications

References 16 publications

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

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

Instability Driven by a Finitely Thick Annular Beam in a Dielectric-Loaded Cylindrical Waveguide

Slow cyclotron instability due to surface modulation of an annular beam

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