110 GHz gyrotron with a built-in high-efficiency converter

Денисов, Г. Г.; Kuftin, A. N.; Малыгин, В. И.; Venediktov, N. P.; Vinogradov, Dmitry; Zapevalov, V. E.

doi:10.1080/00207219208925634

Cited by 144 publications

(42 citation statements)

References 2 publications

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“…Special care has been taken for the design of the quasi-optical mode converter [26,27] to minimize the generation of stray radiation. The radius of the antenna waveguide launcher is slightly up-tapered towards the output by an angle of 4 mrad in order to avoid parasitic oscillations in this region.…”

Section: Iiia the W7-x Gyrotronmentioning

confidence: 99%

Electron Cyclotron Heating for W7-X: Physics and Technology

Erckmann

Brand

Braune

et al. 2007

Fusion Science and Technology

182

127

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Abstract:The W 7-X Stellarator (R = 5.5 m, a = 0.55 m, B<3.0 T), which is presently being built at IPP-Greifswald, aims at demonstrating the inherent steady state capability of stellarators at reactor relevant plasma parameters. A 10 MW ECRH plant with cwcapability is under construction to meet the scientific objectives. The physics background of the different heating-and current drive scenarios is presented. The

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Section: Iiia the W7-x Gyrotronmentioning

confidence: 99%

Electron Cyclotron Heating for W7-X: Physics and Technology

Erckmann

Brand

Braune

et al. 2007

Fusion Science and Technology

182

127

View full text Add to dashboard Cite

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“…Each iteration involves two discrete Fourier transforms and one complex multiply. Using a two-dimensional Fast Fourier transform [17] we can rapidly compute (2). We have implemented this approach in an original FORTRAN code that has been benchmarked against simulated and measured data.…”

Section: F Ementioning

confidence: 99%

“…A typical mode converter consists of a waveguide section with a radiating aperture followed by a series of reflectors (or mirrors), as depicted in Figure 1. The waveguide constitutes either a Vlasov [1] or rippled-wall [2] launcher that directs the microwave energy radially through a wall aperture, separating it from the spent electron beam. The radiated wave is then focussed by a series of reflectors that also serve to guide the microwave beam through a low-loss vacuum window and out of the tube.…”

Section: Introductionmentioning

confidence: 99%

Gyrotron internal mode converter reflector shaping from measured field intensity

Denison

Chu

Shapiro

et al. 1999

IEEE Trans. Plasma Sci.

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We present the formulation and experimental results of a new approach to designing internal mode converter reflectors for high-power gyrotrons. The method employs a numerical phase retrieval algorithm that reconstructs the field in the mode converter from intensity measurements, thus accounting for the true field structure in shaping the beam-forming reflectors. An outline for designing a four-reflector mode converter is presented and generalized to the case of an offset-fed shaped reflector antenna. The requisite phase retrieval and reflector shaping algorithms are also developed without reference to specific mode converter geometry. The design approach is applied to a 110 GHz internal mode converter that transforms the TE 22 6 gyrotron cavity mode into a Gaussian beam at the gyrotron window. Cold test experiment results of the mode converter show that a Gaussian beam with the desired amplitude and phase is formed at the window aperture. Subsequent high-power tests in a 1 MW gyrotron confirm the Gaussian beam observed in cold tests. The general development of the approach and its validation in a quasi-optical mode converter indicate that it is also applicable to other quasi-optical, microwave applications such as radio astronomy, free-space transmission lines, and mitre bends for overmoded waveguides.

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“…These modifications allow one to improve the efficiency of conversion of a rotating circular waveguide mode into a Gaussian beam. In one of the most successful of these designs, a mixture of modes is generated by a rippled wall prior to the launcher so as to form a Gaussian-like beam with little or no sidelobes, thus allowing very high efficiency in the IMC [9]. In a recent paper, the launcher has been optimized numerically using the surface current integral equation method, leading to close to 100 % theoretical efficiency for the IMC [12].…”

Section: Introductionmentioning

confidence: 99%

“…Several optimized modifications of the Vlasov antenna have been reported in the literature ([6], [7], [8], [9], [10], [11]). These modifications allow one to improve the efficiency of conversion of a rotating circular waveguide mode into a Gaussian beam.…”

Section: Introductionmentioning

confidence: 99%

Calculation of Radiation from a Helically Cut Waveguide for a Gyrotron Mode Converter in the Quasi-Optical Approximation

Choi

Shapiro

Sirigiri

et al. 2008

J Infrared Milli Terahz Waves

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A gyrotron internal mode converter consists of a launcher that radiates the waveguide mode as a nearly Gaussian beam in free space, followed by a set of mirrors to focus and direct the radiation.We present a calculation of the radiation from the launcher based on a quasi-optical approach that includes diffraction. The results are in good agreement with a calculation using a numerical code based on the electric field integral equation approach. The results should be useful for designing so-called Vlasov internal mode converters and for understanding the role of diffraction in the design of internal mode converters for gyrotrons.

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110 GHz gyrotron with a built-in high-efficiency converter

Cited by 144 publications

References 2 publications

Electron Cyclotron Heating for W7-X: Physics and Technology

Electron Cyclotron Heating for W7-X: Physics and Technology

Gyrotron internal mode converter reflector shaping from measured field intensity

Calculation of Radiation from a Helically Cut Waveguide for a Gyrotron Mode Converter in the Quasi-Optical Approximation

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