Broadband linearly polarized beat-wave TE/sub m1//TE/sub 11/ mode converters

McDermott, D.B.; Pretterebner, J.; Chong, C.K.; Kinney, C. F.; Razeghi, M. M.; Luhmann, Neville C.

doi:10.1109/22.481581

Cited by 25 publications

(7 citation statements)

References 16 publications

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“…It has interesting features as it can couple two operating modes in the circular waveguide to generate new eigenmodes. It has attracted considerable interest and found its applications in gyrotron backward wave oscillators (gyro-BWOs) [15,16], gyrotron traveling wave amplifiers (gyro-TWAs) [17][18][19], mode converters [20,21], microwave pulse compressors [22,23], and as a microwave undulator [11]. The inner surface of an HCW can be expressed in cylindrical coordinates as ( , ) = 0 + 1 ( + 2 / ) (5) where R 0 is the mean radius of the circular waveguide, R 1 is the corrugation depth, m B is the fold number, and d is the axial period of the corrugation.…”

Section: Hcw As Microwave Undulatormentioning

confidence: 99%

Microwave Undulator Using a Helically Corrugated Waveguide

Zhang

Clarke

et al. 2018

IEEE Trans. Electron Devices

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Microwave undulators (MU) can be an alternative to the permanent magnet undulators in a free electron laser (FEL). MUs normally employ a cavity-type structure that supports the standing wave to boost the electromagnetic field strength. In this paper, a waveguide-type MU based on a helically corrugated waveguide (HCW) that supports a traveling wave is studied. The use of the HCW allows partial conversion of a traveling wave mode into a backward traveling wave mode, hence increasing the effective interaction length. When operating with a TE11 mode at 30.3 GHz, the MU was predicted to realize a field strength of ~0.3 T and an undulator period of 4.95 mm when driven by 1 GW of microwave power.Index Terms-microwave undulator, free electron laser, helically corrugated waveguide, traveling wave mode.

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Section: Hcw As Microwave Undulatormentioning

confidence: 99%

Microwave Undulator Using a Helically Corrugated Waveguide

Zhang

Clarke

et al. 2018

IEEE Trans. Electron Devices

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“…From the azimuthal synchronism condition, a fold number of 4 is required. The period of the mode convertor will satisfy the axial synchronism condition , where and are the axial wavenumbers of the mode and the spatial harmonic of the mode [23], [24]. The geometry was refined and verified by using the 3-D FDTD code CST Microwave Studio after the preliminary theoretical analysis.…”

Section: Design Of the Waveguide Components For Microwave Compresmentioning

confidence: 99%

Experimental Study of Microwave Pulse Compression Using a Five-Fold Helically Corrugated Waveguide

Zhang

Mishakin

et al. 2015

IEEE Trans. Microwave Theory Techn.

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This paper presents the experimental study of microwave pulse compression using a five-fold helically corrugated waveguide. In the experiment, the maximum power compression ratio of 25.2 was achieved by compressing an input microwave pulse of 80-ns duration and 9.65-9.05-GHz frequency swept range into a 1.6-ns Gaussian-envelope pulse. For an average input power of 5.8 kW generated by a conventional traveling-wave tube, a peak pulse output power of 144.8 kW was measured corresponding to an energy efficiency of 66.3%.

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“…14) are still in the design phase, and their broadband capability is still hindered owing to a lack of mode converters in the low terahertz region. 15,16 Inline coupling 17,18 and sidewall coupling 15,16,19,20 have been exploited to convert circular TE mn modes. The former, generally requiring a long converting region, is subject to parasitic oscillations in the gyrotron and is thus disfavored.…”

Section: Introductionmentioning

confidence: 99%

Broadband conversion of TE01 mode for the coaxial gyrotron at low terahertz

2012

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This paper investigates the mode characteristics of coaxial waveguide and proposes a mechanism to convert a rectangular TE 10 mode to a coaxial TE 01 mode. Four-wave, eight-wave, and sixteen-wave coupling structures are developed to selectively excite the desired coaxial TE 01 mode with different outer to inner radius ratios. The proposed structures can suppress the unwanted parasitic modes and lead to high converting efficiency with broad bandwidth. The measured 3-dB transmission bandwidths at W-band are 13.5 GHz (14.3%), 8.5 GHz (9.0%), and 12.2 GHz (13.0%), respectively. These coaxial TE 01 mode converters are mutually non-overlapping in their coaxial cross-sections, and therefore can be joined concentrically and utilized to develop a multi-channel gyrotron traveling-wave tube or backward-wave oscillator in a single superconducting magnet. V C 2012 American Institute of Physics. [http://dx.

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Broadband linearly polarized beat-wave TE/sub m1//TE/sub 11/ mode converters

Cited by 25 publications

References 16 publications

Microwave Undulator Using a Helically Corrugated Waveguide

Microwave Undulator Using a Helically Corrugated Waveguide

Experimental Study of Microwave Pulse Compression Using a Five-Fold Helically Corrugated Waveguide

Broadband conversion of TE01 mode for the coaxial gyrotron at low terahertz

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