Coupled-Mode Theory of an Irregular Waveguide with Impedance Walls

Maksimenko, Aleksandr V.; Shcherbinin, Vitalii I.; Ткаченко, В. І.

doi:10.1007/s10762-019-00589-x

Cited by 14 publications

(5 citation statements)

References 50 publications

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“…Metasurfaces have unique abilities to block, absorb, concentrate, disperse or guide waves on the surface at a grazing incidence angle and in space at normal and oblique incidence, from microwave to visible frequencies. Surface waves can be well controlled by designing impedance cells to manipulate phase or group velocity [ 40 , 41 ]. These are patterned in such a way that may guide or separate waves in certain directions, and/or used to control scattering.…”

Section: Evolution Of Metamaterialsmentioning

confidence: 99%

Metamaterials and Metasurfaces: A Review from the Perspectives of Materials, Mechanisms and Advanced Metadevices

2022

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Throughout human history, the control of light, electricity and heat has evolved to become the cornerstone of various innovations and developments in electrical and electromagnetic technologies. Wireless communications, laser and computer technologies have all been achieved by altering the way light and other energy forms act naturally and how to manage them in a controlled manner. At the nanoscale, to control light and heat, matured nanostructure fabrication techniques have been developed in the last two decades, and a wide range of groundbreaking processes have been achieved. Photonic crystals, nanolithography, plasmonics phenomena and nanoparticle manipulation are the main areas where these techniques have been applied successfully and led to an emergent material sciences branch known as metamaterials. Metamaterials and functional material development strategies are focused on the structures of the matter itself, which has led to unconventional and unique electromagnetic properties through the manipulation of light—and in a more general picture the electromagnetic waves—in widespread manner. Metamaterial’s nanostructures have precise shape, geometry, size, direction and arrangement. Such configurations are impacting the electromagnetic light waves to generate novel properties that are difficult or even impossible to obtain with natural materials. This review discusses these metamaterials and metasurfaces from the perspectives of materials, mechanisms and advanced metadevices in depth, with the aim to serve as a solid reference for future works in this exciting and rapidly emerging topic.

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Section: Evolution Of Metamaterialsmentioning

confidence: 99%

Metamaterials and Metasurfaces: A Review from the Perspectives of Materials, Mechanisms and Advanced Metadevices

2022

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“…Moreover, contrary to [16,17,19,23,29], we propose to equip the gyrotron cavity with a uniform coaxial insert, which can be more easily fabricated to close tolerances and causes no or little mode conversion. Note that although the effect of mode conversion is well-known [43][44][45][46][47], its influence on the beam-wave interaction in gyrotron cavities still remains poorly explored [48].…”

Section:  mentioning

confidence: 99%

Mode Discrimination by Lossy Dielectric Rods in Cavities of Second-Harmonic Gyrotrons

Shcherbinin

Avramidis

Thumm

et al. 2021

J Infrared Milli Terahz Waves

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The influence of a coaxial dielectric rod on eigenvalues, ohmic losses, transverse field structure and beam-wave coupling coefficients is investigated for TE modes of a gyrotron cavity. It is shown that such dielectric insert, when made from a moderate-loss material, results in strong attenuation of all cavity modes, with the exception of those having caustic radii much larger than the insert radius. It is proposed to employ such dielectric loading for selective suppression of competing modes in cavities of second-harmonic gyrotrons. The high performance and flexibility of the proposed method of mode discrimination is demonstrated for the example of the cavity of the high-power 0.39-GHz second-harmonic gyrotron developed at the University of Fukui. In addition, some fascinating capabilities enabled by coaxial inserts made of ultralow-loss dielectrics are discussed.

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“…1). We neglect conversion of radial cavity modes due to slow variation of the cavity radius   R z [26][27][28][29][30], and first assume that the cavity is made of a perfect electric conductor. Such a corrugated cavity supports pure TE modes ( 0 z E  ).…”

Section: Gyrotron Equationsmentioning

confidence: 99%

“…Contrary to conventional cylindrical cavities, these cavities, however, can exhibit unwanted conversion between coupled radial modes due to abrupt change of the longitudinal (axial) structure. Even though such mode conversion is well-studied in cold cavities [26][27][28][29][30], its effect on the beam interaction with first-and second-harmonic modes still remains poorly explored [31] and therefore may present a hidden factor in designing the advanced cavities for secondharmonic gyrotrons.…”

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confidence: 99%

Starting currents of modes in cylindrical cavities with mode-converting corrugations for second-harmonic gyrotrons

Tkachova

Shcherbinin

Ткаченко

et al. 2021

J Infrared Milli Terahz Waves

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A self-consistent system of equations (known as single-mode gyrotron equations) is extended to describe the beam-wave interaction in a cylindrical gyrotron cavity with mode-converting longitudinal corrugations, which produce coupling of azimuthal basis modes. The system of equations is applied to investigate the effect of corrugations on starting currents of the cavity modes. For these modes, eigenvalues, ohmic losses, field structure and beam-wave coupling coefficients are investigated with respect to the corrugation parameters. It is shown that properly-sized mode-converting corrugations are capable of improving the selectivity properties of cylindrical cavities for second-harmonic gyrotrons.

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Coupled-Mode Theory of an Irregular Waveguide with Impedance Walls

Cited by 14 publications

References 50 publications

Metamaterials and Metasurfaces: A Review from the Perspectives of Materials, Mechanisms and Advanced Metadevices

Metamaterials and Metasurfaces: A Review from the Perspectives of Materials, Mechanisms and Advanced Metadevices

Mode Discrimination by Lossy Dielectric Rods in Cavities of Second-Harmonic Gyrotrons

Starting currents of modes in cylindrical cavities with mode-converting corrugations for second-harmonic gyrotrons

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