High-Efficiency Excitation of a Third-Harmonic Gyrotron

Qi, Xian-Rong; Du, Chao‐Hai; Liu, Pu‐Kun

doi:10.1109/ted.2015.2461657

Cited by 19 publications

(5 citation statements)

References 41 publications

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“…In order to reduce the boundary reflection, perfect-matched layers are loaded at both ends of the cavity to approximate the outgoing-wave boundary. [43] In a word, the frequency-domain code is effective for the prediction of possible steady states of a single mode, while the time-domain code is capable of simulating the start-oscillation scenario of multimode interaction. Both methods were verified in a series of previous publications.…”

Section: Discussionmentioning

confidence: 99%

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Forward-wave enhanced radiation in the terahertz electron cyclotron maser

Gao

Du²,

Li³

et al. 2022

Chinese Phys. B

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Based on the principle of electron cyclotron maser (ECM), gyrotrons are among the most promising devices to generate powerful coherent terahertz (THz) radiation and play a vital role in numerous advanced THz applications. Unfortunately, THz ECM systems using a conventional high-Q cavity were theoretically and experimentally demonstrated to suffer from strong ohmic losses, and, accordingly, the wave output efficiency was significantly reduced. A scheme to alleviate such a challenging problem is systematically investigated in this paper. The traveling-wave operation concept is employed in a 1-THz third harmonic gyrotron oscillator, which strengthens electron-wave interaction efficiency and reduces the ohmic dissipation, simultaneously. A lossy belt is added in the interaction circuit to stably constitute the traveling-wave interaction, and a down-tapered magnetic field is employed to further amplify the forward-wave (FW) component. The results demonstrate that the proportion of ohmic losses is nearly halved, and output efficiency is nearly doubled, which is promising for further advancement of high-power continuous-wave operation of the ECM-based devices.

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Section: Discussionmentioning

confidence: 99%

“…Appendix A: Self-consistent nonlinear theory First, the nonlinear theory in the frequency domain is presented as follows. Based on the assumption of steady single-mode operation, the electron-wave interaction equation is given by [43,44]…”

mentioning

confidence: 99%

Forward-wave enhanced radiation in the terahertz electron cyclotron maser

Gao

Du²,

Li³

et al. 2022

Chinese Phys. B

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“…When it comes to the time domain, Equation turns into the following form

\frac{\partial^{2}}{\partial z^{2}} f (z, t) - k_{m n}^{2} f (z, t) - μ ε \frac{\partial^{2}}{\partial t^{2}} f (z, t) = 0

From TE mode expression in Equation , k mn is a complex number.…”

Section: Constant Frequency Methodsmentioning

confidence: 99%

Strong Dispersive Propagation of Terahertz Wave: Time‐Domain Self‐Consistent Modeling of Metallic Wall Losses

Gao

et al. 2020

Advcd Theory and Sims

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The dispersion characteristics of electromagnetic waves have led to a wide range of applications, such as pulse compression, superluminal propagation, wave tunneling effect, and electron–wave interaction. The near‐cutoff wave inside a guiding system is strong dispersive. When the wave frequency reaches the terahertz band, this strong dispersive property is extremely sensitive to the losses induced by the limited conductivity of the component. This phenomenon is traditionally investigated through perturbation of boundary conditions in the frequency domain, which does not deal well with broad‐spectrum signals. Two simple and efficient time‐domain schemes to study the strong dispersive propagation of terahertz waves are proposed. One is based on relatively concise principles, called the constant frequency method. The second is the recursive convolution method, which is suitable for dealing with a wave with wider spectrum range. The reliability of both approaches is verified by the comparison of the dispersion curves. Using the proposed methods, the pulse compression of terahertz wave inside a strong dispersive waveguide is verified in principle.

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“…In this case σeff equals 1.45×10 7 S/m (~0.25σ0). By substituting the evaluation of H-B formula into the impedance wall, it is convenient to combine the surface roughness with the analytical models including the steady-state frequency-domain theory [28], [29], [30] and the multimode time-domain theory [31], [32].…”

Section: Model For Surface Roughnessmentioning

confidence: 99%

Design of a 1-THz Fourth-Harmonic Gyrotron Driven by Axis-Encircling Electron Beam

Zhang

et al. 2022

IEEE Trans. Electron Devices

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In this paper, the design of a 4 th -harmonic gyrotron with 1-kW-level output power at 1 terahertz (THz) is presented. A unique advantage of this design is that, with a well-optimized magnetic-cusp large-orbit electron gun, the designed gyrotron can operate from 1 st harmonic to 4 th harmonic in multiple discrete bands by varying the operating voltage. By carefully balancing the competing modes, the gyrotron can be tuned to operate at six candidate modes, including TE1,2 for fundamental harmonic, TE2,3 and TE2,4 for 2 nd harmonic, TE3,5 and TE3,6 for 3 rd harmonic, and TE4,8 for 4 th harmonic interactions. As the main operating mode, the TE4,8 can generate a peak output power of 1.68 kW, with an efficiency of about 2.1%, and a magnetically controlled frequency tuning range of about 1.8 GHz around 1 THz. The impact of the longitudinal nonuniformity of the cavity at high-harmonic interaction was also studied. It shows a radial tolerance of several micrometers will significantly elevate the start-oscillation current and deteriorate output performance. This design is towards the development of a synthesizing THz source with ultra-wideband tuning capability ranging from the sub-millimeter-wave to 1-THz bands.Index Terms-high harmonic terahertz gyrotron, multi-mode switching, broad-range magnetic tuning.

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High-Efficiency Excitation of a Third-Harmonic Gyrotron

Cited by 19 publications

References 41 publications

Forward-wave enhanced radiation in the terahertz electron cyclotron maser

Forward-wave enhanced radiation in the terahertz electron cyclotron maser

Strong Dispersive Propagation of Terahertz Wave: Time‐Domain Self‐Consistent Modeling of Metallic Wall Losses

Design of a 1-THz Fourth-Harmonic Gyrotron Driven by Axis-Encircling Electron Beam

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