Competition between Harmonic Cyclotron Maser Interactions in the Terahertz Regime

Kao, Shih-Han; Chiu, Chien Chao; Pao, K.F.; Chu, K. R.

doi:10.1103/physrevlett.107.135101

Cited by 47 publications

(24 citation statements)

References 20 publications

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“…We shall theoretically analyze three mode-competition criteria and their interplay, which determine the eventually dominant mode. Multi-mode, time-dependent simulations reveal an intrinsic tendency for a higher-harmonic mode to switch over to a lower-harmonic mode at a high beam current or upon a rapid current rise [33,34]. These studies are helpful to identify the narrow windows in the parameter space for stable harmonic interactions.…”

Section: Physics Issuesmentioning

confidence: 99%

Some recent progresses on electron cyclotron maser research

Chu

2015

2015 IEEE International Vacuum Electronics Conference (IVEC)

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Over a span of five decades, the electron cyclotron maser (ECM) has undergone a remarkably successful evolution from basic research to a poweiful millimeter, sub-millimeter, and THz wave generator called the gyrotron, while continuously being enriched by major advances. Below we discuss the ECM principle and its significance, followed by an overview of recent progresses made in two specific areas: THz gyrotron oscillators and millimeter-wave gyro-TWT ampltfiers. Topics �f the talk will include selected examples of device performances, ongoing/potential applications, and relevant physics issues.Each class of vacuum electronic devices is distinguishable by its characteristic bunching mechanism to convert an electron current from DC to AC. The ECM interaction [1][2][3][4] features a simple relativistic bunching mechanism. As shown in Fig. 1, in an applied DC magnetic field (Ba) andin the presence of a perpendicular RF electric field, the relativistic cyclotron frequency (Qc) decreases (increases) for energy-gaining (losing) electrons, which results in electron bunching along the cyclotron orbit. The ECM interaction takes place in a smooth fast-wave structure, as well as allowing the resonant excitation of a very high order mode (Fig. 2). It can thus generate output powers orders of magnitude greater than previously achievable. gain energy, eB � Q c = � azimuthal / bunching .

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Section: Physics Issuesmentioning

confidence: 99%

Some recent progresses on electron cyclotron maser research

Chu

2015

2015 IEEE International Vacuum Electronics Conference (IVEC)

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“…Both can efficiently predict the potential steady states of the ECM system in frequency domain [44]. The timedomain multi-mode theory is actually a 1-D FDTD theory [37], [45] which can precisely predict the time dependent multi-mode competition process.…”

Section: A Theorymentioning

confidence: 99%

“…It normally operates on an extremely high-order mode. A step-tunable gyrotron consecutively shifts over a series of independent modes by applying magnetic field tuning and generates high power radiation on discrete frequencies [24]- [26], [37], [38]. A gyro-BWO operates based on the internal feedback mechanism between the electron beam and backward wave.…”

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confidence: 99%

Broadband Tunable Pre-Bunched Electron Cyclotron Maser for Terahertz Application

Du¹,

Qi²,

Liu³

et al. 2015

IEEE Trans. THz Sci. Technol.

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The relativistic electron cyclotron maser (ECM) has been successfully applied to generating high-power THz wave. In order to realize the additional advantages of broadband tuning and high efficiency interaction, this paper is devoted to exploring the THz pre-bunched ECM. Other than a conventional open-cavity tunable gyrotron consecutively switching between axial modes to realize frequency tuning, a pre-bunched ECM system operates on the backward traveling-wave resonance to achieve broadband smooth tuning. Especially, an interaction circuit of specified axial profile of beam-wave detuning frequency is built to achieve high efficiency. An optimized 0.1 THz pre-bunched ECM system using an electron beam of 30 kV voltage and 3 A current is predicted to generate broad bandwidth of 10 GHz and efficiency between 10% 25%. The broadband tuning pre-bunched ECM is promising for a new generation of broadband and high-power THz source.Index Terms-Broadband tuning, coherent radiation, electron cyclotron maser (ECM), terahertz (THz).

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“…The gyroton traveling-wave-tube amplifier (gyro-TWT) is a major type of gyrotron in the millimeter and sub-millimeter regions. Although a design for a 1-MW gyro-TWT at frequency 140 GHz with 18.7% efficiency has been demonstrated [2], the gyrotron device receives little attention in the THz region, because of problems of heat dissipation from a small interaction structure and mode competition [3].…”

Section: Introductionmentioning

confidence: 99%