Journal articles: 'Traveling-wave Tube (TWT)'

1

Jin, Hai Wei, Lan Zhang, Jie Liu, and Xu Qian. "The Progress of Millimeter / Submillimeter Wave TWT Research." Applied Mechanics and Materials 705 (December 2014): 219–22. http://dx.doi.org/10.4028/www.scientific.net/amm.705.219.

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Millimeter / Submillimeter wave traveling wave tubes have the merits of high output power, frequency bandwidth, compact, light weight, etc. Millimeter / Submillimeter wave traveling wave tube is an ideal millimeter / submillimeter radiation source, can be used in fields of radar, electronic warfare, communication, etc. The paper introduced and summarized the research status of foreign Millimeter / submillimeter TWT wave tube, analyzed and discussed its trend.

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Jang, Kwang-Ho, Jong-Hyun Kim, Geun-Ju Kim, Jung-Il Kim, and Jin-Joo Choi. "Experiments of Sub-THz Wave Folded Waveguide Traveling-Wave Tube Amplifier." Journal of Electromagnetic Engineering and Science 23, no. 2 (March 31, 2023): 42–48. http://dx.doi.org/10.26866/jees.2023.2.r.160.

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This study showed the possibility of using a sub-terahertz (THz) traveling-wave tube (TWT) via measuring the transmission characteristics and TWT performance of the circuit by applying X-ray LIGA, a micro-fabrication process, to the interaction circuit. The applied circuit type, an E-bend folded waveguide, is a simple structure most suitable for lithography. A total of three applied frequencies were used the W-band, G-band, and 850 GHz. Among the manufactured circuits, the W-band circuit was applied to the TWT, one of the vacuum electronics devices (VEDs). This was done to prove the manufacturing accuracy of the circuit by comparing the nonlinear characteristics of the circuit with the prediction results. Through such testing, the small signal gain was measured as 13 ± 2 dB under the conditions of 13.96-kV and 24.2-mA electron beam energy. The frequency bandwidth was extremely wide, about 9 GHz, and showed similar characteristics to the simulation predictions. The maximum output of the device was obtained up to 1 W or more at 87.12 GHz by slightly increasing the beam current. These characteristic achievements showed the suitability of the TWT for very small circuits fabricated using the X-ray LIGA process, further suggesting the applicability of other sub-THz bands.

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Li, Ying, Pan Pan, Bowen Song, Lin Zhang, and Jinjun Feng. "A 237 GHz Traveling Wave Tube for Cloud Radar." Electronics 12, no. 10 (May 9, 2023): 2153. http://dx.doi.org/10.3390/electronics12102153.

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In this article, the first 237 GHz traveling wave tube (TWT) is presented as a high-power amplifier for the terahertz (THz) cloud radar. As is common with previous G-band traveling wave tubes developed at Beijing Vacuum Electronics Research Institute, the 237 GHz traveling wave tube employs a 20 kV, 50 mA pencil electron beam focused using periodic permanent magnets (PPMs) to achieve compactness. A folded waveguide (FWG) slow-wave structure (SWS) with modified circular bends is optimized to provide high impedance and eliminate sideband oscillations. Limited by insufficient drive power, this device is not saturated. The measured maximum output power and gain are 8.9 W and 35.7 dB, and the 3 dB gain bandwidth achieves 4 GHz.

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Торгашов, Р. А. "Замедляющая система меандрового типа на диэлектрической подложке для лампы бегущей волны миллиметрового диапазона." Журнал технической физики 46, no. 23 (2020): 25. http://dx.doi.org/10.21883/pjtf.2020.23.50344.18472.

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А novel planar microstrip meander-line slow-wave structure (SWS) on dielectric substrate for a miniature low-voltage millimeter-band traveling-wave tube (TWT) with a high-aspect-ratio sheet electron beam is proposed. Main electromagnetic parameters of the SWS were studied. Using of such a slow-wave structure may lead to increase of the gain and output power of the TWT-amplifier

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Song, Heather H. "Calculation of Start-Oscillation-Current for Lossy Gyrotron Traveling-Wave Tube (Gyro-TWT) Using Linear Traveling-Wave Tube (TWT) Parameter Conversions." Journal of Electromagnetic Analysis and Applications 05, no. 01 (2013): 1–4. http://dx.doi.org/10.4236/jemaa.2013.51001.

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Zhuge, Tianxiang, and Yulu Hu. "Design of a Novel High Power V-Band Helix-Folded Waveguide Cascaded Traveling Wave Tube Amplifier." Active and Passive Electronic Components 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/846425.

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A design of a V-band Helix-Folded Waveguide (H-FWG) cascaded traveling wave tube (TWT) is presented. In this cascaded structure, a digitized nonlinear theory model is put forward first to simulate these two types of the tubes by common process. Then, an initial design principle is proposed, which can design these two different kinds of tubes universally. Using this principle, a high-gain helix TWT is carefully designed as a first stage amplifier followed by a FWG TWT to obtain high power. Simulations predict that a peak power of 800 W with saturated gain of 60 dB from 55 GHz to 60 GHz can be achieved.

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Kurayev, A. A., and V. V. Matveyenka. "TERAHERTZ TRAVELING-WAVE TUBE ON A RECTANGULAR WAVEGUIDE FOLDED IN A CIRCULAR SPIRAL." Doklady BGUIR, no. 7-8 (December 29, 2019): 81–85. http://dx.doi.org/10.35596/1729-7648-2019-126-8-81-85.

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The most promising in the THz range is traveling-wave tubes (TWTs) and backward-wave tubes (BWTs) on a serpentine-curved (zigzag-rolled) rectangular waveguide. They are implemented in the THz range (220 GHz), although their characteristics are far from satisfactory due to the strict restriction on the tape electron beam width, that does not allow reaching the summarizing beam current optimum level. To replace the zigzag convoluted waveguide with the spiraled for the TWT and BWT on a curved rectangular waveguide is the best way to remove the ribbon beam width restriction. In the early TWT and BWT design a waveguide planar spiral was also flat in the upper and lower parts connected by vertical idle (without beam) transitions. Proposed design can be significantly improved both in relation to the electron interaction process with the waveguide field and in relation to the TWT-BWT manufacturing technology if instead of a planar waveguide spiral, a circular one is used. The article proposes the TWT designing a terahertz rectangular waveguide folded as a circular spiral. The design differs from the previously proposed TWT with a planar-spiral waveguide by the improved interaction conditions between the electron beam and the waveguide field, as well as the manufacturing technology simplification for terahertz range. Based on numerical simulation, it is shown that proposed TWT achieves Gн = 42÷48 dB saturation gain in the 220 GHz range with the waveguide turn number n = 40÷50. The proposed TWT design on a rectangular waveguide folded in a circular spiral is more technologically advanced than the TWT on a planar-spiral waveguide. In the most necessary 220 GHz range the efficiency is very high and can provide the need for amplifiers and generators in this and other ranges. We also note that the TWT on a spirally folded waveguide can operate in the BWT mode and, moreover, simultaneously in the TWT and BWT modes.

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Luo, Jinjing, Jin Xu, Pengcheng Yin, Ruichao Yang, Lingna Yue, Zhanliang Wang, Lin Xu, Jinjun Feng, Wenxin Liu, and Yanyu Wei. "A 340 GHz High-Power Multi-Beam Overmoded Flat-Roofed Sine Waveguide Traveling Wave Tube." Electronics 10, no. 23 (December 3, 2021): 3018. http://dx.doi.org/10.3390/electronics10233018.

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A phase shift that is caused by the machining errors of independent circuits would greatly affect the efficiency of the power combination in traditional multi-beam structures. In this paper, to reduce the influence of the phase shift and improve the output power, a multi-beam shunted coupling sine waveguide slow wave structure (MBSC-SWG-SWS) has been proposed, and a multi-beam overmoded flat-roofed SWG traveling wave tube (TWT) based on the MBSC-SWG-SWS was designed and analyzed. A TE10-TE30 mode convertor was designed as the input/output coupler in this TWT. The results of the 3D particle-in-cell (PIC) simulation with CST software show that more than a 50 W output power can be produced at 342 GHz, and the 3 dB bandwidth is about 13 GHz. Furthermore, the comparison between the single-beam sine waveguide (SWG) TWT and the multi-beam overmoded SWG TWT indicates that the saturated output power of the multi-beam overmoded SWG TWT is three times more than that of the single beam SWG TWT.

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Gehrmann, Elke, Philip Birtel, Wolfgang Dürr, Frédéric André, and Arne F. Jacob. "Second Harmonic Suppression in S-Band Traveling Wave Tube Tapers." Frequenz 69, no. 1-2 (December 20, 2014): 11–20. http://dx.doi.org/10.1515/freq-2014-0125.

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Abstract Traveling wave tubes (TWTs) operating at S-band are to be improved by suppressing the second harmonic frequency. Among the different possibilities, two techniques, namely harmonic injection and a filter helix for frequency selective signal suppression, are studied in more detail and applied to S-band tubes in both simulation and measurement. In addition, their suitability to improve tube performance by reducing the second harmonic is discussed. Moreover, filter helix implementation in TWTs with an arbitrary pitch profile along the interaction area is considered. In this context, the dependence of the pitch discontinuity reflection coefficient on several filter helix parameters is investigated. The influence of those parameters on the filter performance is shown by filter helix optimization. Measurement results of the optimized filter helix TWT are presented.

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Feng, Yuan, Xingwang Bian, Bowen Song, Ying Li, Pan Pan, and Jinjun Feng. "A G-Band Broadband Continuous Wave Traveling Wave Tube for Wireless Communications." Micromachines 13, no. 10 (September 29, 2022): 1635. http://dx.doi.org/10.3390/mi13101635.

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Development of a G-band broadband continuous wave (CW) traveling wave tube (TWT) for wireless communications is described in this paper. This device provides the saturation output power over 8 W and the saturation gain over 30.5 dB with a bandwidth of 27 GHz. The maximum output power is 16 W and the bandwidth of 10 W output power is 23 GHz. The 3 dB bandwidth is greater than 12.3% of fc (center frequency). The gain ripple is less than 10 dB in band. A pencil beam of 50 mA and 20 kV is used and a transmission ratio over 93% is realized. The intercept power of the beam is less than 70 W and the TWT is conduction cooled through mounting plate and air fan, which makes the device capable of operating in continuous wave mode. A Pierce’s electron gun and periodic permanent magnets are employed. Chemical vapor deposition diamond disc is used in the input and output radio frequency (RF) windows to minimize the loss and voltage standing wave ratios of the traveling wave tube. Double stages deeply depressed collector is used for improving the total efficiency of the device, which can be over 5.5% in band. The weight of the device is 2.5 kg, and the packaged size is 330 mm × 70 mm × 70 mm.

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11

Titov, Vladimir, Andrey Ploskih, and Nikita Ryskin. "Study of Beam–Wave Interaction in a Sub-THz Traveling Wave Tube with a Converging Sheet Electron Beam Focused by a Uniform Magnetic Field." Electronics 11, no. 24 (December 16, 2022): 4208. http://dx.doi.org/10.3390/electronics11244208.

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A traveling-wave tube (TWT) with a sheet electron beam and staggered double-grating slow-wave structure (SWS) is a promising high-power, wideband terahertz amplifier. In such tubes, electron-optical systems (EOSs) with a converging sheet beam are mostly used, which allow a reduction of the cathode load, increase the lifetime, and enable operation in a continuous-wave (CW) mode. This paper presents the results of a 3D particle-in-cell (PIC) simulation of the 0.22 THz TWT driven with a converged sheet beam, which is compressed to less than 100 μm thickness in the EOS with a magnetically shielded cathode. The beam with high compression has a significant transversal velocity spread and essentially non-uniform current density distribution over the cross-section. These factors significantly affect the beam–wave interaction. We compare the performance of the TWT driven by the compressed sheet beam and by an idealized initially rectilinear beam without any velocity spread.

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12

Xiong, Ying, Xianfeng Tang, Juncheng Ma, and Liping Yu. "Miniaturized Metamaterial-Inspired Travelling Wave Tube for S Band." Electronics 12, no. 14 (July 13, 2023): 3062. http://dx.doi.org/10.3390/electronics12143062.

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A miniaturized traveling wave tube (TWT) was studied by proposing a novel metamaterial (MTM) slow wave structure (SWS). The dispersion results show that n = −1 space harmonic of the fundamental mode exhibits the “forward” wave properties, which is the foundation of the MTM-inspired TWT. Meanwhile, the interaction impedance for mode 2 of the novel MTM SWS can be sharply decreased by introducing four blend edges to weaken the corresponding longitudinal electric field. Also, two coaxial couplers are presented to input/output the signals. The transmission results show that the reflection is as low as −15 dB from 2.90 GHz to 3 GHz, which ensures the amplified signal can be effectively outputted. The MTM-inspired TWT exhibits miniaturized superiority for its compact high frequency structure including the MTM SWS and the coaxial couplers. Especially, for the high-frequency structure, the transverse and longitudinal sizes are ~λ/5 and ~3λ, respectively (λ is the free-space wavelength at the operating frequencies). The simulation of the beam wave interaction shows that the proposed MTM-inspired TWT yields output powers of kW levels from 2.90 GHz to 3 GHz, with a gain of 23.5–25.8 dB and electronic efficiency of 14–22% when the beam current is 0.5 A and the beam voltage is 13 kV. The results indicate that the gain per wavelength is as high as 8.5 dB in the operating bands. The simulation results confirm that it is possible to weaken the backward wave oscillation from the higher mode in the miniaturized MTM-inspired TWT.

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Ruan, J. F., J. Yang, G. Q. Lv, G. S. Deng, and L. Liu. "Structure Optimization of Space Helix TWT Based on Thermal Analysis." Applied Mechanics and Materials 130-134 (October 2011): 1753–57. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1753.

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The main components of a space helix TWT (traveling wave tube) are electron gun, helix slow-wave system and collector. Thermal issue is of great importance for space helix TWTs. High heat efficiency of cathode is required for electron gun, as well as high heat transmission capacity for slow-wave system and collector. Some structure optimization for the electron gun, slow-wave system and the collector of some type of space helix TWT has been proposed aiming the above purpose. To evaluate the structural optimization means, the related thermal analysis has been carried out using ANSYS software. The simulation results demonstrate that the structure optimization is effective. And the actual effect needs to be further studied.

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14

Chbiki, Mounir, Najib Laraqi, Jean-François Jarno, Jacques Herrewyn, and Tony da Silva Botelho. "Thermal analysis of a transmission line for Traveling Wave Tube TWT." Journal of Physics: Conference Series 395 (November 26, 2012): 012023. http://dx.doi.org/10.1088/1742-6596/395/1/012023.

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Гришин, C. В., and В. Н. Скороходов. "Генерация темных импульсов огибающей в модифицированной схеме шумотрона." Письма в журнал технической физики 49, no. 18 (2023): 37. http://dx.doi.org/10.21883/pjtf.2023.18.56176.19516.

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The generation of dark envelope pulses with a duration of about 10 ns is obtained in a modified noisetron circuit consisting of two nonlinear amplifiers: a multicavity drift klystron and a travel-ing wave tube (TWT), captured by a delayed feedback circuit. The drift klystron operates in the output power saturation mode, and the TWT amplifier operates in the nonlinear cross mode, in which there are two N-shaped sections on the amplitude characteristic of the lamp, and the phase shift dependence on the signal power at the traveling wave tube entrance is highly nonlinear. It is shown that an increase in the chaotic signal power in a ring leads not only to a decrease in the average repetition period of dark envelope pulses, but also to the formation of bound states of dark and anti-dark envelope pulses.

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Bian, Xingwang, Min Miao, Zhensong Li, and Xiaole Cui. "U-shaped meander-line slow-wave structure with stub-loading." Modern Physics Letters B 31, no. 16 (June 2017): 1750173. http://dx.doi.org/10.1142/s0217984917501731.

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In this paper, a U-shaped meander-line slow-wave structure (SWS) with stub-loading is proposed for applications in Ka-band traveling-wave tube (TWT). This new slow-wave structure, loaded with a stub at the center of the U-turn section, has higher interaction impedance and lower phase velocity compared with conventional U-shaped meander-line SWSs, indicating that the devices based on this structure may have a lower operating voltage and higher output power. The dispersion characteristic, interaction impedance, transmission characteristics, and beam-wave interaction are simulated by utilizing simulation tool. The simulation result predicts that the millimeter-wave traveling-wave tube design based on this slow-wave structure is capable of delivering over 200 W with a gain of 33 dB and interaction efficiency 14.5% at the center frequency 34 GHz. This design, more compact and powerful in comparison with those based on more conventional vacuum electronic mechanisms, is demonstrated as a prospective option for integrated millimeter-wave power modules (MMPMs) empowering a broad spectrum of fields, from target detection, to imaging and telecommunications, among others.

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Торгашов, Р. А., Н. М. Рыскин, А. Г. Рожнев, А. В. Стародубов, А. А. Сердобинцев, А. М. Павлов, В. В. Галушка, И. Ш. Бахтеев, and С. Ю. Молчанов. "Теоретическое и экспериментальное исследование миниатюрной планарной замедляющей системы на диэлектрической подложке для лампы бегущей волны W-диапазона." Журнал технической физики 90, no. 4 (2020): 686. http://dx.doi.org/10.21883/jtf.2020.04.49096.294-19.

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The research results of a miniature meander planar slow-wave structure (SWS) for W-band traveling wave tube are presented. 3D computer simulation of the electrodynamic parameters of SWS has been carried out. A new technology of manufacturing of planar microstrip SWS has been presented. An experimental research of the S-parameters of an SWS has been carried out. The results show good agreement with the results of 3D simulation. The output characteristics of the TWT with sheet electron beam and planar SWS on dielectric substrate were simulated.

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Гришин, С. В., Б. С. Дмитриев, Ф. П. Разуваев, В. Н. Скороходов, В. Н. Титов, and Д. И. Трубецков. "Нелинейное подавление сигналов в лампе бегущей волны." Журнал технической физики 91, no. 11 (2021): 1774. http://dx.doi.org/10.21883/jtf.2021.11.51543.129-21.

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The results of an experimental and theoretical study of the passage of monochromatic and pulse-modulated microwave signal through a traveling wave tube operating in the nonlinear suppression mode are presented. It was found that the TWT can operate either as a saturable absorber or as a power limiter and these regimes depend on the magnitude of the accelerating voltage and beam current. In the first case, the maximum signal suppression level corresponding to the Kompfner dip is realized in the linear mode, and in the second case - in the nonlinear mode, at a certain input signal power. It is shown that in the case of maximum suppression, a short pulse is formed at the front of the radio pulses. In the nonlinear Kompfner dip mode, the duration of such pulse is decreased with an increase in the power of the input radio pulse. The simulation results obtained using the nonlinear nonstationary theory of a traveling wave tube are in good qualitative agreement with the experimental data.

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Zhou, Shuanghong, Yuanlin Yao, Yuting Zhang, and Bin Ge. "Electromagnetic Particle Algorithm for Beam–Wave Interaction in Traveling Wave Tube of Symmetry." Symmetry 14, no. 10 (October 12, 2022): 2119. http://dx.doi.org/10.3390/sym14102119.

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In many fields, such as space astrophysics, plasma and vacuum electronics, there are many nonlinear strong coupling physical problems. In order to solve the problem of electron beam–wave interaction in cylindrical Traveling wave tube (TWT) with symmetrical structure, a multi particle simulation algorithm for beam circuit is designed. The algorithm allows aperiodic time input, nonuniform linearity and large space diagnosis for different particles. In this algorithm, the field of coupled slow-wave transmission line is simulated by finite difference method. Assuming that there is strong coupling between the beam and the circuit, the space center equation of transmission along the line is obtained, and the space charge field is modeled considering the space charge effect, which can easily be ignored. The Particle In Cell (PIC) method of frog leaping step scheme is adopted to evaluate the electric field of each particle center, determine the circuit and space charge field, and design the termination part to compensate for the loss in order to avoid self-excited agitation. Finally, a simple numerical simulation is carried out for the electromagnetic problem and the accuracy of the code is checked against the electromagnetic simulator CHPIC. Therefore, the algorithm can be used to solve the problem of beam–wave interactions in a fixed structure (cylindrical) in multiple fields and can accurately record the data in the process.

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Kumar, Vikas. "Attenuation Measurement of Lossy Coatings of Carbon for Ka-Band Helix TWT Applications." International Journal of Surface Engineering and Interdisciplinary Materials Science 7, no. 1 (January 2019): 55–61. http://dx.doi.org/10.4018/ijseims.2019010104.

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In a high efficiency traveling wave tube (TWT) amplifier, any reflections present in the device may cause oscillations and hence instability. A coating of lossy material on appropriate parts of the tubes (known as attenuators) is done to suppress these reflections. Carbon is a very commonly used material for this type of coating, and may be deposited by a number of techniques. In the present work, coatings of carbon were done on the dielectric substrate and evaluated for the attenuation performance at microwave frequencies. Three dielectric rods (APBN material) were coated with carbon by pyrolytic deposition method for different thickness. An experimental setup involving a rectangular wave-guide with a hole has been used for measuring the attenuation of the coated rods in the Ka-band frequency range. The same structure has been simulated using the Ansoft High Frequency Simulator (HFSS) and both the experimental and simulated results have been compared.

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Yang, Ruichao, Lingna Yue, Jin Xu, Pengcheng Yin, Jinjing Luo, Hexin Wang, Dongdong Jia, et al. "Broadband-Printed Traveling-Wave Tube Based on a Staggered Rings Microstrip Line Slow-Wave Structure." Electronics 11, no. 3 (January 27, 2022): 384. http://dx.doi.org/10.3390/electronics11030384.

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To increase the output power of microstrip line traveling-wave tubes, a staggered rings microstrip line (SRML) slow-wave structure (SWS) based on a U-shaped mender line (U-shaped ML) SWS and a ring-shaped microstrip line (RML) SWS has been proposed in this paper. Compared with U-shaped ML SWS and RML SWS, SRML SWS has a wider transverse width, which means SRML SWS has a larger area for beam–wave interaction. The simulation results show that SRML SWS has a wider bandwidth than U-shaped ML SWS and a lower phase velocity than RML SWS. Input/output couplers, which consist of microstrip probes and transition sections, have been designed to transmit signals from a rectangular waveguide to the SWS; the simulation results present that the designed input/output structure has good transmission characteristics. Particle-in-cell (PIC) simulation results indicate that the SRML TWT has a maximum output of 322 W at 32.5 GHz under a beam voltage of 9.7 kV and a beam current of 380 mA, and the corresponding electronic efficiency is around 8.74%. The output power is over 100 W in the frequency range of 27 GHz to 38 GHz.

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Wang, Zechuan, Junwan Zhu, Zhigang Lu, Jingrui Duan, Haifeng Chen, Shaomeng Wang, Zhanliang Wang, Huarong Gong, and Yubin Gong. "A Novel Staggered Double-Segmented Grating Slow-Wave Structure for 340 GHz Traveling-Wave Tube." Sensors 23, no. 10 (May 15, 2023): 4762. http://dx.doi.org/10.3390/s23104762.

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In this paper, a novel staggered double-segmented grating slow-wave structure (SDSG-SWS) is developed for wide-band high-power submillimeter wave traveling-wave tubes (TWTs). The SDSG-SWS can be considered as a combination of the sine waveguide (SW) SWS and the staggered double-grating (SDG) SWS; that is, it is obtained by introducing the rectangular geometric ridges of the SDG-SWS into the SW-SWS. Thus, the SDSG-SWS has the advantages of the wide operating band, high interaction impedance, low ohmic loss, low reflection, and ease of fabrication. The analysis for high-frequency characteristics shows that, compared with the SW-SWS, the SDSG-SWS has higher interaction impedance when their dispersions are at the same level, while the ohmic loss for the two SWSs remains basically unchanged. Furthermore, the calculation results of beam–wave interaction show that the output power is above 16.4 W for the TWT using the SDSG-SWS in the range of 316 GHz–405 GHz with a maximum power of 32.8 W occurring at 340 GHz, whose corresponding maximum electron efficiency is 2.84%, when the operating voltage is 19.2 kV and the current is 60 mA.

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Lu, Chaoxuan, Wei Jiang, Zewei Wu, Guo Liu, Jianxun Wang, Youlei Pu, and Yong Luo. "Design and Measurement of a Novel Overmoded TE01 Mode Converter for a Rectangular Gyro-TWT." Micromachines 13, no. 7 (July 15, 2022): 1111. http://dx.doi.org/10.3390/mi13071111.

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The rectangular gyrotron traveling wave tube (gyro-TWT) with a large aspect ratio (α) has the potential to achieve megawatt-class output power. As an essential component of gyro-TWT, a novel overmoded Ka-band mode converter with an α of 6.19 is designed, analyzed, and cold tested in this paper. Based on the magnetic dipole moment theory, the rectangular overmoded TE01 mode is excited via the rectangular fundamental TE10 mode. The cutoff waveguide is applied to prevent electromagnetic wave transport to the magnetron injection gun (MIG) region and also guarantee higher power electron beam transportation. Simulations predict an operation bandwidth higher than 4 GHz and greater than 99.8% mode purity between 33–37 GHz. To verify this design, the mode converter is manufactured and cold tested. The back-to-back measurement results exhibit a good agreement with the simulation. With similar topologies, the rectangular overmoded TE01 mode can be excited in a different α.

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Li, Peng, Sheng Xiang Bao, De Zheng Zhang, Li Bo Zhuang, and Li Li Ma. "Application of Secondary Electron Composition Contrast Imaging Method in Microstructure Studies on Cathode Materials of TWT." Materials Science Forum 689 (June 2011): 255–59. http://dx.doi.org/10.4028/www.scientific.net/msf.689.255.

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The study of the secondary electron composition contrast imaging method have been developed with a conventional scanning electron microscope (SEM) equipped with ultra-thin window energy dispersive X-ray spectrometer (EDS). On the basis of the study of the principle of secondary electron emission, secondary electron composition contrast imaging method has been investigated, and the ranges of its application were also discussed. This method was applied in the microstructure studies on cathode materials of TWT (traveling wave tube). The results showed that, compared with backscattered electron image, the secondary electron image could also reveal composition contrast well in certain conditions. Furthermore, the resolution of secondary electron composition contrast image is higher. In some cases, the secondary electron image could distinguish impurities which might bring wrong results. In the microstructure studies on cathode materials of TWT, compared with backscattered electron image, secondary electron composition contrast imaging method is reasonable and practicable.

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Guo, Guo, Zhenlin Yan, Zhenzhen Sun, Jianwei Liu, Ruichao Yang, Yubin Gong, and Yanyu Wei. "Broadband and Integratable 2 × 2 TWT Amplifier Unit for Millimeter Wave Phased Array Radar." Electronics 10, no. 22 (November 16, 2021): 2808. http://dx.doi.org/10.3390/electronics10222808.

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A novel power amplifier unit for a phased array radar with 2 × 2 output ports for a vacuum electron device is proposed. Double parallel connecting microstrip meander-lines are employed as the slow-wave circuits of a large power traveling wave tube operate in a Ka-band. The high frequency characteristics, the transmission characteristics, and the beam–wave interaction processes for this amplifier are simulated and optimized. For each output port of one channel, the simulation results reveal that the output power, saturated gain, and 3-dB bandwidth can reach 566 W, 27.5 dB, and 7 GHz, respectively. Additionally, the amplified signals of four output ports have favorable phase congruency. After fabrication and assembly, transmission tests for the 80-period model are performed preliminarily. The tested “cold” S-parameters match well with the simulated values. This type of integratable amplifier combined with a vacuum device has broad application prospects in the field of high power and broad bandwidth on a millimeter wave phased array radar.

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Chbiki, Mounir, Silva da, Jean-Gabriel Bauzin, Najib Laraqi, and Jean-Francois Jarno. "Thermal effect on the thermomechanical behavior of contacts in a Traveling Wave Tube." Thermal Science 20, no. 6 (2016): 1983–90. http://dx.doi.org/10.2298/tsci141216010c.

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A new elasto-plastic study of the contact between the helix and the rods of the delay line of Traveling Waves Tubes (TWT) was realized. Our study is focused on the analysis of the hot lines shrinking phenomenon. In the studied case, unlike brazed configuration, the contact areas are not perfect, resulting in a diminution of the heat transfer process. In order to maximize the contact area and to homogenize the contact pressure, a soft thermal conductive material is coated on the helix: copper was chosen for this study. In the present work, an analytical model is used to identify the properties of the copper coating at a given temperature. We focused on the mechanical properties in order to improve the assembly process with a better numerical study. Experimental method have been made to validate the proposed model. The first comparison results seem to indicate that the model represents the reality with a good agreement. It is very clearly shown that the temperature decreases the mechanical properties. (Young?s modulus, yield strength, tensile strength?). And the thickness of the coating increases the contact area. This last point is less important at room temperature (6% of increase) than at 140?C (22%).

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Wang, Yuxin, Yang Dong, Xiangbao Zhu, Jingyu Guo, Duo Xu, Shaomeng Wang, and Yubin Gong. "Multiple Dielectric-Supported Ridge-Loaded Rhombus-Shaped Wideband Meander-Line Slow-Wave Structure for a V-Band TWT." Electronics 11, no. 3 (January 28, 2022): 405. http://dx.doi.org/10.3390/electronics11030405.

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A multiple dielectric-supported ridge-loaded rhombus-shaped meander-line (MDSRL-RSML) slow-wave structure (SWS) is proposed for a V-band wideband traveling wave tube (TWT). The high-frequency and transmission characteristics of the SWS are investigated. The proposed structure can realize stable output via attenuator and special phase-velocity jumping. Particle-in-cell (PIC) results indicate that, for a 7 kV, 0.1 A sheet-beam, the average output power can reach 60 W at 60 GHz and a 3 dB bandwidth of 9 GHz, with the corresponding gain and electron efficiency of 30.8 dB and 17.2%, respectively. Compared with the dielectric-supported rhombus-shape meander-line (DS-RSML) SWS, the proposed structure has a wider bandwidth, higher gain, more stable structure, and better heat dissipation ability, which make it a good candidate source in millimeter-wave communications.

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Safi, Djamschid, Philip Birtel, Sascha Meyne, and Arne F. Jacob. "Comparative study of envelope models for hybrid time- and frequency-domain simulation of traveling-wave tubes." International Journal of Microwave and Wireless Technologies 10, no. 5-6 (April 3, 2018): 521–29. http://dx.doi.org/10.1017/s1759078717001349.

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A selection of hybrid frequency- and time-domain approaches is evaluated with respect to their suitability for predicting the multi-tone behavior of a reference Ku-band helix traveling-wave tube. For this, a frequency-domain code is extended by a selection of frequency-dependent and frequency-independent envelope models and compared to a number of simulated and measured responses to two-tone signal excitation with varying frequency spacing. The selected envelope methods are investigated both in the hybrid approach and based on measured TWT characteristics. Output levels and classical multi-tone metrics, such as intermodulation products and phase transfer factors, are considered. By reducing a modulation scenario to a number of significant sequences, a comparison to full physics-based frequency-domain simulation is presented to show the potential of the proposed approach.

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29

Wang, Hexin, Shaomeng Wang, Zhanliang Wang, Xinyi Li, Tenglong He, Duo Xu, Zhaoyun Duan, Zhigang Lu, Huarong Gong, and Yubin Gong. "Study of an Attenuator Supporting Meander-Line Slow Wave Structure for Ka-Band TWT." Electronics 10, no. 19 (September 28, 2021): 2372. http://dx.doi.org/10.3390/electronics10192372.

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An attenuator supporting meander-line (ASML) slow wave structure (SWS) is proposed for a Ka-band traveling wave tube (TWT) and studied by simulations and experiments. The ASML SWS simplifies the fabrication and assembly process of traditional planar metal meander-lines (MLs) structures, by employing an attenuator to support the ML on the bottom of the enclosure rather than welding them together on the sides. To reduce the surface roughness of the molybdenum ML caused by laser cutting, the ML is coated by a thin copper film by magnetron sputtering. The measured S11 of the ML is below −20 dB and S21 varies around −8 dB to −12 dB without the attenuator, while below −40 dB with the attenuator. Particle-in-cell (PIC) simulation results show that with a 4.4-kV, 200-mA sheet electron beam, a maximum output power of 126 W is obtained at 38 GHz, corresponding to a gain of 24.1 dB and an electronic efficiency of 14.3%, respectively.

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30

Lo Gerfo, Fabio Paolo, and Patrizia Livreri. "Optimal Design of an X-Band, Fully-Coaxial, Easily-Tunable Broadband Power Equalizer for a Microwave Power Module." Electronics 9, no. 5 (May 18, 2020): 829. http://dx.doi.org/10.3390/electronics9050829.

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A microwave power module (MPM), which is a hybrid combination of a solid-state power amplifier (SSPA) as a driver and a traveling-wave tube amplifier (TWT) as the final high power stage, is a high-power device largely used for radar applications. A gain equalizer is often required to flatten the TWT output power gain owing to its big gain fluctuations over the operating frequency range. In this paper, the design of an X-band, fully-coaxial, easily-tunable broadband power equalizer for an MPM is presented. The structure is composed of a coaxial waveguide as the main transmission line and a coaxial cavity loaded with absorbing material as a resonant unit. Sensitivity analyses of the attenuation amplitude and resonant frequency of the equalizer in terms of coaxial cavity length, thickness of the absorbing disc, and insertion depth of the probe were carried out. The measured results were in good agreement with the simulated ones, showing that the equalization curve met the requirements well and proved that this optimal structure has the advantages of a large power capacity, a wide operating frequency band, is easily tunable, and good transmission performance.

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31

Zhang, Ruifeng, Qi Wang, Difu Deng, Yao Dong, Fei Xiao, Gil Travish, and Huarong Gong. "Novel Dual Beam Cascaded Schemes for 346 GHz Harmonic-Enhanced TWTs." Electronics 10, no. 2 (January 16, 2021): 195. http://dx.doi.org/10.3390/electronics10020195.

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The applications of terahertz (THz) devices in communication, imaging, and plasma diagnostic are limited by the lack of high-power, miniature, and low-cost THz sources. To develop high-power THz source, the high-harmonic traveling wave tube (HHTWT) is introduced, which is based on the theory that electron beam modulated by electromagnetic (EM) waves can generate high harmonic signals. The principal analysis and simulation results prove that amplifying high harmonic signal is a promising method to realize high-power THz source. For further improvement of power and bandwidth, two novel dual-beam schemes for high-power 346 GHz TWTs are proposed. The first TWT is comprised of two cascaded slow wave structures (SWSs), among which one SWS can generate a THz signal by importing a millimeter-wave signal and the other one can amplify THz signal of interest. The simulation results show that the output power exceeds 400 mW from 340 GHz to 348 GHz when the input power is 200 mW from 85 GHz to 87 GHz. The peak power of 1100 mW is predicted at 346 GHz. The second TWT is implemented by connecting a pre-amplification section to the input port of the HHTWT. The power of 600 mW is achieved from 338 GHz to 350 GHz. The 3-dB bandwidth is 16.5 GHz. In brief, two novel schemes have advantages in peak power and bandwidth, respectively. These two dual-beam integrated schemes, constituted respectively by two TWTs, also feature rugged structure, reliable performance, and low costs, and can be considered as promising high-power THz sources.

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32

Zhao, Dongming, Huijuan Liu, Kewen Xia, Shi Li, and Xiaoxu Shi. "Simultaneous Suppression of IMD3 and IMD5 in Space TWT by IMD3 and 2HD Signal Injection." Active and Passive Electronic Components 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/4721048.

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This paper presents a signal injection technology showing significant reductions in both 3rd-order and 5th-order intermodulation distortions (IMD3 and IMD5) in space traveling wave tube (STWT). By applying the IMD3 to the IMD5 ratio (TFR) as measures of location, the simultaneous suppressions of IMD3 and IMD5 in TWT are achieved by second harmonic distortion (2HD) and IMD3 injection. According to the research on theoretical analysis and computer simulation, the optimum amplitude and phase parameters of the injected signal for maximum simultaneous suppressions are obtained. Then an experiment system is established based on vector network analyzer, optimum TFR are 2.1 dB and 12.5 dB, respectively, by second harmonic and IM3 injection, and the output powers of IMD3 and IMD5 were decreased. TFR with IMD3 injection is smaller than that with second harmonic injection in STWT, and the experiment system is more straightforward and easy to operate. Thus, the IMD3 injection performs better than that of second harmonic injection to suppress IMD5s for the narrow-band STWT.

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33

Zhang, Changqing, Pan Pan, Xueliang Chen, Siming Su, Bowen Song, Ying Li, Suye Lü, Jun Cai, Yubin Gong, and Jinjun Feng. "Design and Experiments of the Sheet Electron Beam Transport with Periodic Cusped Magnetic Focusing for Terahertz Traveling-Wave Tubes." Electronics 10, no. 24 (December 7, 2021): 3051. http://dx.doi.org/10.3390/electronics10243051.

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The successful transport of a sheet electron beam under the periodic cusped magnet (PCM) focusing at the terahertz frequencies is reported. The sheet beam with a current density of 285 A/cm2 is intended for the developing G-band sheet-beam traveling-wave tube (TWT) whose operating voltage is nominally 24.5 kV. A beamstick was developed to validate the design of the electron optics system, which is considered as the most challenging part for developing a sheet-beam device. A beam transmission ratio of 81% is achieved over a distance of 37.5 mm at a cathode voltage of −25.0 kV. The total current and the collector current were measured to be 125 and 102 mA, respectively. The experimental results are promising, demonstrating that the PCM scheme is capable of focusing a high-current-density sheet beam and hence can find use in the terahertz TWTs, offering the advantages of compact size and light weight.

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34

Wang, Xiaoning, Xiaobao Su, and Jinjing Wang. "Nonlinear Doubly Wiener Constant-Stress Accelerated Degradation Model Based on Uncertainties and Acceleration Factor Constant Principle." Applied Sciences 11, no. 19 (September 26, 2021): 8968. http://dx.doi.org/10.3390/app11198968.

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Although Wiener process models with the consideration of uncertainties, which are nonlinearity, random effects, and measurement errors, have been developed for lifetime prediction in the accelerated degradation test (ADT), they fail to describe the real degradation process because these models assume that the drift parameter correlates with the applied stress, while the diffusion parameter is constant. This paper put forward a nonlinear doubly Wiener constant-stress accelerated degradation model, where both diffusion and drift parameters were compatible with the applied stress according to the acceleration factor constant principle. When degradation data were available, we obtained the unknown parameters by applying a maximum likelihood estimation (MLE) algorithm in the constant-stress ADT (CSADT) model taking uncertainties into account. In addition, the proposed model’s effectiveness was validated through an illustrative example, and an application to the traveling wave tube (TWT) was carried out to demonstrate the superiority of our model in practical applications.

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35

Muramatsu, Masayuki, Shinji Nomura, Shuhei Harisaki, Yushi Kato, Yasushi Abe, Mihiro Watanabe, Ken Katagiri, and Atsushi Kitagawa. "Experiment of two-frequency heating for production of multiply charged ion at compact ECR ion source." Journal of Physics: Conference Series 2244, no. 1 (April 1, 2022): 012016. http://dx.doi.org/10.1088/1742-6596/2244/1/012016.

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Abstract Several research and developments have been performed at a compact ECR ion source (Kei3) with a fixed magnetic field at HIMAC. The Kei3 is a testing machine for application of Kei series developed for high-energy carbon-ion radiotherapy. It is difficult for Kei3 to produce ions that are heavier than carbon ion because it uses the same magnetic field distribution as the Kei series. In order to improve the beam current of multiply charged ions such as neon and argon, the two-microwave-frequency heating method was tested in the Kei3. Microwaves are introduced into the plasma chamber with a WR-90 rectangular waveguide. A traveling wave tube (TWT) amplifier made by the NEC (LD79X75A1) is used as the microwave source. The frequency band is 9.75-10.25 GHz and the maximum output power is 750 W. The WR-75 waveguide is also introduced from the upper part of the upstream vacuum chamber and installed on top of the existing the WR-90 waveguide. A TWT amplifier manufactured by the Xicom (XTRD-300IJ) was used as a microwave source for the two-microwave-frequency heating. The frequency band is 10-18 GHz and the maximum output power is 300 W. A beam test with oxygen, neon, and argon was performed in order to confirm the effect of two microwave frequency heating. In this test, we focused on O6+, Ne7+, and Ar9+ ions. We measured the dependence of the XTRD-300IJ microwave frequency and the microwave power of the LD79X75A1 on a charge state distributions.

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36

Muramatsu, Masayuki, Shinji Nomura, Shuhei Harisaki, Yushi Kato, Yasushi Abe, Mihiro Watanabe, Ken Katagiri, and Atsushi Kitagawa. "Experiment of two-frequency heating for production of multiply charged ion at compact ECR ion source." Journal of Physics: Conference Series 2244, no. 1 (April 1, 2022): 012016. http://dx.doi.org/10.1088/1742-6596/2244/1/012016.

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Abstract Several research and developments have been performed at a compact ECR ion source (Kei3) with a fixed magnetic field at HIMAC. The Kei3 is a testing machine for application of Kei series developed for high-energy carbon-ion radiotherapy. It is difficult for Kei3 to produce ions that are heavier than carbon ion because it uses the same magnetic field distribution as the Kei series. In order to improve the beam current of multiply charged ions such as neon and argon, the two-microwave-frequency heating method was tested in the Kei3. Microwaves are introduced into the plasma chamber with a WR-90 rectangular waveguide. A traveling wave tube (TWT) amplifier made by the NEC (LD79X75A1) is used as the microwave source. The frequency band is 9.75-10.25 GHz and the maximum output power is 750 W. The WR-75 waveguide is also introduced from the upper part of the upstream vacuum chamber and installed on top of the existing the WR-90 waveguide. A TWT amplifier manufactured by the Xicom (XTRD-300IJ) was used as a microwave source for the two-microwave-frequency heating. The frequency band is 10-18 GHz and the maximum output power is 300 W. A beam test with oxygen, neon, and argon was performed in order to confirm the effect of two microwave frequency heating. In this test, we focused on O6+, Ne7+, and Ar9+ ions. We measured the dependence of the XTRD-300IJ microwave frequency and the microwave power of the LD79X75A1 on a charge state distributions.

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37

Al-Kanan, Haider, and Fu Li. "A Simplified Accuracy Enhancement to the Saleh AM/AM Modeling and Linearization of Solid-State RF Power Amplifiers." Electronics 9, no. 11 (October 31, 2020): 1806. http://dx.doi.org/10.3390/electronics9111806.

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The Saleh behavioral model exhibits high prediction accuracy for nonlinearity of traveling-wave tube power amplifiers (TWT-PAs). However, the accuracy of the Saleh model degrades when modeling solid-state power amplifiers (SSPAs) technology. In addition, the polynomial expansion of the Saleh model consists of only odd-order terms as analyzed in this work. This paper proposes a novel model accuracy enhancement for the Saleh amplitude-to-amplitude (AM/AM) model when applied to radio frequency (RF) SSPAs. The proposed model enhancement accounts for the second-order intermodulation distortion, which is an important nonlinearity challenge in wideband wireless communications. The proposed static AM/AM model is a three-parameter rational function, which exhibits low complexity compared to the state-of-the-art behavioral models. A transpose architecture of finite-impulse digital filter is used to quantify the memory effect in SSPAs. A least-squares method is used for extracting all the model parameters. A linearization technique using a three-parameter digital predistortion model is also calculated to compensate for the AM/AM nonlinear distortion in SSPAs. Finally, the identification and evaluation of the enhanced Saleh model is presented based on measurements of RF SSPAs.

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38

De Weese, K. L., C. E. Toups, and C. K. H. Dharan. "Analysis of Brazing Stresses in Ceramic-Metal Joints in High-Vacuum Devices." Journal of Electronic Packaging 111, no. 1 (March 1, 1989): 21–25. http://dx.doi.org/10.1115/1.3226503.

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Significant stresses are induced in brazed metal-to-ceramic joints during cool-down. Analysis of such stresses is complicated by nonlinear material behavior and uncertainties in material properties at and near the braze temperatures. In this study, stresses induced during cool-down from the brazing temperature are analytically determined for a coaxial RF (radio frequency) window, which is an integral component of many traveling-wave tube (TWT) devices. The approach is to use nonlinear finite element analysis which takes into account plastic deformation of the metal components as well as the temperature dependence of material properties. Details of the modeling techniques, analytical assumptions and boundary conditions employed are discussed. In addition, metallographic analysis of the brazed test assemblies is described. Analytically predicted stress distributions showed reasonably good correlation with both the location and direction of cracks observed in the ceramic component of brazed sample test assemblies. The results of this investigation emphasize the need for accurate material properties for the braze alloys used in such joints, including temperature dependence, as well as an understanding of their nonlinear behavior, for the stress analysis model to be accurate. In addition, the important role of joint geometry in the minimization of cool-down stresses in brazed metal-ceramic assemblies is described.

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39

Jia, Dongdong, Hairong Yin, Jin Xu, Lingna Yue, Ruichao Yang, Pengcheng Yin, Jinjing Luo, et al. "Bandwidth enhancement for over-mode traveling-wave amplifiers." Physics of Plasmas 29, no. 8 (August 2022): 083105. http://dx.doi.org/10.1063/5.0097224.

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To increase the bandwidth of conventional over-mode traveling wave tubes (TWTs) with single-mode existing (SME) in an operation band, a theory on over-mode TWTs with multi-modes coexisting (MME) in the operation band is presented in this paper. To verify this theory, G-band dual-beam and shunted coupled Hughes-type coupled-cavity TWTs with MME and SME are investigated. The particle-in-cell simulation analysis confirms that, compared with SME TWT, the MME TWT can not only operate stably but also has 2.24 times bandwidth and a large increase in the output power.

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40

Aksenchyk, A. V., and I. F. Kirynovich. "Traveling-wave tubes on looping waveguides with a potential jump." Doklady BGUIR 19, no. 5 (August 26, 2021): 29–34. http://dx.doi.org/10.35596/1729-7648-2021-19-5-29-34.

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Using computer simulation, a study of the effect of a potential jump on the interaction processes in O-type traveling-wave tubes has been carried out. In these devices, the interaction of the electron beam with a slowed down electromagnetic wave is carried out. To slow down the electromagnetic wave, various electrodynamics systems are used: spiral, on chains of coupled resonators, etc. In this work, we have chosen a slowing down system in the form of a chain of looping rectangular waveguides. Its advantage is that it has a wide bandwidth and each link in such a chain is coordinated with the adjacent ones. To assess the effect of a potential jump on the interaction processes in O-type traveling-wave tubes, a mathematical model has been developed, which takes into account most fully all the factors influencing the interaction processes. These include: relativistic effects during the motion and interaction of electrons, sagging of fields in the gaps of the waveguide, losses in the walls of the waveguide, taking into account the space charge fields (taking into account the periodization of the fields). Based on the developed model, a program was compiled and calculations of various variants of TWT were carried out for accelerating voltages of 20–500 kV, electron beam currents of 0.3...160 A. When performing calculations, the gap with a potential jump was located in different places of the TWT slow-wave structure and its location was chosen where the maximum effect on the electron bunching processes is manifested. As the calculations have shown, the potential jump makes it possible to increase the output power of the TWT by 15–20 %. It can be noted for comparison that the use of a potential jump in multi-cavity klystrons [1] also leads to an increase in the output power by 15-25 %. This confirms the reliability of the mathematical models used in TWT and klystrons.

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41

Alaria, Mukesh Kumar, and Sanjay Kumar Ghosh. "Design of coaxial and waveguide couplers for helix TWT." Frequenz 75, no. 5-6 (February 1, 2021): 159–63. http://dx.doi.org/10.1515/freq-2020-0117.

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Abstract In this paper, two types of coaxial coupler and waveguide coupler for different frequency helix traveling wave tubes (TWTs) are designed, fabricated and cold tested. The coaxial coupler includes of window ceramic and RF transformer section. At present multi-section impedance transformer design approach is used for wideband helix TWTs. In any helix TWT, impedance of the source is transformed to the characteristic impedance of helix. This is done by the quarter-wavelength (λ/4) impedance transformation approach. The simulated results of different types of couplers are carried out by HFSS and CST microwave studio software and compare with experimental results. Three-dimensional electromagnetic field simulators allowing the any geometry with port excitations it is possible to model the complex coaxial and waveguide type couplers with helix SWS assembly and predict its desired return loss performances.

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42

Bai, Chun-Jiang, Jian-Qing Li, and Yu-Lu Hu. "A 2.5-D frequency-domain nonlinear computer model of coupled-cavity traveling wave tubes." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 33, no. 5 (August 26, 2014): 1777–93. http://dx.doi.org/10.1108/compel-09-2012-0156.

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Purpose – The purpose of this paper is to present a 2.5-dimensional (2.5-D) frequency-domain nonlinear computer model for the beam-wave interaction of coupled-cavity traveling wave tubes (CC-TWTs). Design/methodology/approach – MKK (proposed by Malykhin, Konnov, and Komarov) equivalent circuit model is used to describe the coupled-cavity slow-wave structure. And the losses are taken into account in the MKK equivalent circuit. Instead of one-dimensional (1-D) disk model, the electron beam is divided into a set of discrete rays and the electron dynamics are treated using the three-dimensional (3-D) Lorentz force equations. Findings – The simulated result obtained show that the computer model can give a good predict for CC-TWTs in V-band. Practical implications – The computer model is capable of treating nonlinear problems. Compared with particle-in-cell simulation, the 2.5-D frequency-domain computer model spends less time. Besides, the 3-D electron trajectory can be used to design high-efficiency collectors for CC-TWTs. Originality/value – The computer model is able to simulate nonlinear problems of coupled-cavity TWT faster.

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43

Vilkov, M. N., L. A. Yurovskiy, and N. S. Ginzburg. "Increasing the amplitude of ultrashort microwave pulses in a passive mode-locked oscillator by the method of double nonlinear filtering." Physics of Plasmas 29, no. 9 (September 2022): 093110. http://dx.doi.org/10.1063/5.0106672.

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We show the possibility of increasing the amplitude of ultrashort microwave pulses in a passive mode-locked oscillator in a circuit containing a chain of traveling wave tubes (TWTs) one of which operates in the amplification regime and the other two in the nonlinear Kompfner suppression regime. An increase in the number of nonlinear filtering stages makes it possible to enhance the filtering threshold level, below which low background noise is suppressed, while an almost complete transparency is maintained for peak amplitudes of the pulse signal. As a result, with an increase in the length of the amplifier, a linear growth in the peak amplitude of microwave pulses takes place because of the commutative extraction of energy from different electron fractions, along which the pulse is shifted due to the difference in its group velocity from the translational velocity of the particles. With an optimal selection of the parameters of the absorbers, the peak amplitude of the generated periodic sequence of ultrashort pulses can exceed the amplitude of stationary generation by more than an order of magnitude for given parameters of the TWT like current, voltage, and coupling impedance.

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Makarov, Sergey B., Mingxin Liu, Anna S. Ovsyannikova, Sergey V. Zavjalov, ILya Lavrenyuk, Wei Xue, and Yidong Xu. "A Reduction of Peak-to-Average Power Ratio Based Faster-Than-Nyquist Quadrature Signals for Satellite Communication." Symmetry 13, no. 2 (February 20, 2021): 346. http://dx.doi.org/10.3390/sym13020346.

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The increase in the throughput of digital television and radio broadcasting (DVB) channels can be achieved due to application of signals with a compact spectrum and a relatively small peak-to-average power ratio (PAPR). The reason is the usage of traveling wave tubes (TWT) for amplifying and transmitting signals from a satellite repeater in DVB-S2X systems. At the same time, given that the bandwidth allocated for transmission should be used as efficiently as possible, a high reduction rate of out-of-band emissions level is required. The most effective solution in this direction is the transition to spectrum-economic signals, such as optimal Faster-Than-Nyquist (FTN) signals, which can provide a certain reduction rate of the out-of-band emissions level and minimum acceptable PAPR. This article proposes a method for obtaining optimal FTN pulses, which have symmetry in time domain, with specified PAPR and reduction rate of out-of-band emissions for the quadrature phase shift keying (QPSK) and offset quadrature phase shift keying (OQPSK). The possibility of synthesizing signals with OQPSK modulation is presented theoretically for the first time. Optimal FTN signals can provide PAPR reduction by at most 3 dB and outperform known root raised cosine (RRC) pulses. The simulation model adopts an architecture for quadrature generation of optimal FTN signals with OQPSK modulation with blocks for adjustable pre-amplification, clipping, and power amplification. The proposed signals can be used to increase the spectral and energy efficiencies of satellite broadcasting systems, such as DVB-S2/S2X, as well as low-rate return channels of interactive broadcasting systems with a frequency resource shortage.

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45

Bible, D. W., R. J. Lauf, and C. A. Everleigh. "Multikilowatt Variable Frequency Microwave Furnace." MRS Proceedings 269 (1992). http://dx.doi.org/10.1557/proc-269-77.

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ABSTRACTWe describe a new type of microwave processing furnace in which the frequency can be varied continuously from 4 to 8 GHz and the power level varied from zero up to 2.5 kW. The extraordinary bandwidth of this furnace is achieved by using a traveling wave tube (TWT) amplifier originally developed for electronic warfare applications. The TWT is a linear beam device characterized by a traveling electromagnetic wave that continuously extracts energy longitudinally along the path of an electron beam. The TWT, unlike other microwave tubes such as the magnetron, klystron, gyrotron, and others, does not depend upon resonant RF fields and is therefore capable of wide bandwidth operation.

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Zhang, Luqi, Yi Jiang, Wenqiang Lei, Peng Hu, Jun Guo, Rui Song, Xianfeng Tang, Guowu Ma, Hongbin Chen, and Yanyu Wei. "A piecewise sine waveguide for terahertz traveling wave tube." Scientific Reports 12, no. 1 (June 21, 2022). http://dx.doi.org/10.1038/s41598-022-14587-y.

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AbstractIn this paper, a piecewise sine waveguide (PWSWG) is proposed as the slow-wave structure (SWS) to develop high-power terahertz (THz) traveling wave tubes (TWTs). The PWSWG is an improvement over the rectangular waveguide wherein its two E-planes simultaneously oscillate up and down along the longitudinal direction. The oscillation curve in the H-plane is a piecewise sine curve formed by inserting line segments into the peaks and troughs of the sine curve. The simulation analysis and experimental verification show that the PWSWG offers the advantages of large interaction impedance and excellent electromagnetic transmission performance. Furthermore, the calculation results of beam–wave interaction show that the TWT based on PWSWG SWS can generate a radiated power of 253.1 W at the typical frequency of 220 GHz, corresponding to a gain of 37.04 dB and an interaction efficiency of 6.92%. Compared with the conventional SWG TWTs, the PWSWG TWT has higher interaction efficiency and shorter saturation tube length. In conclusion, the PWSWG proposed in this paper can be considered a suitable SWS for high-power THz radiation sources.

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47

Rozental, R. M., V. V. Klinshov, S. V. Samsonov, A. A. Bogdashov, and I. G. Gachev. "Chaotic signal generation in a CW K-band gyro-TWT with strong output reflections." Physics of Plasmas 30, no. 8 (August 1, 2023). http://dx.doi.org/10.1063/5.0153308.

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We experimentally study the dynamics of a K-band continuous wave gyro-resonant traveling wave tube (gyro-TWT) with strong output reflections. By varying system parameters, we have obtained transitions from periodic self-modulation regimes with line spectra to more complex oscillation regimes. We present the analysis of experimental data verifying the experimental observation of chaotic oscillation regimes. We have shown that chaotic oscillation regimes emerge in a fairly narrow parameter area, about 0.5% of magnetic field strength and about 10% of reflectivity. Maximum oscillation power reaches 0.5 kW at about 2% efficiency. For a gyro-TWT with output reflections operating in the CW mode, the chaotic oscillations are being experimentally observed and systematically analyzed for the first time.

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Volosova, A. A., I. A. Almaev, A. B. Danilov, and A. Yu Miroshnichenko. "Evaluation of the influence of solid-phase connection technology on the heat dissipation ability of the SWS and the reliability of the TWT in the centimeter range." Journal of Radio Electronics 2020, no. 11 (November 2020). http://dx.doi.org/10.30898/1684-1719.2020.11.4.

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The article is devoted to the problems associated with the development of powerful traveling wave tube - heat removal from highly loaded elements. The aim of the study was to obtain a design of a slow wave structure of a high-power TWT by the solid-phase connection method and to assess the heat dissipation capacity of the resulting design. The article describes the increase of the heat dissipation capacity in spiral decelerating TWT systems. Various methods of fastening spiral pipes using ceramic support rods have been investigated. A technology has been developed and a design of a decelerating system of a high-power broadband TWT using a solid-phase connection of a spiral and supporting ceramic rods has been obtained. The heat dissipation capacity of the resulting structure is estimated. Improving the heat dissipation ability, increasing the efficiency of the device and increasing the reliability of the product.

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Everleigh, C. A., A. C. Johnson, R. J. Espinosa, and R. S. Garard. "Use of High-Power Traveling Wave Tubes as a Microwave Heating Source." MRS Proceedings 347 (1994). http://dx.doi.org/10.1557/proc-347-79.

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ABSTRACTThis paper reports on the use of high-power traveling wave tubes (TWTs) as a source of microwave energy for materials processing applications. Recent work by Oak Ridge National Laboratories and Microwave Laboratories personnel has demonstrated the usefulness of sweeping the microwave processing frequency over substantial (>20%) bandwidths in order to achieve uniformity of heating over volumes unattainable using conventional microwave sources ∼ e.g., magnetrons. Properly constructed high-power TWTs are a logical choice of microwave source in such systems. After briefly reviewing the basic operating principles of the TWT, the required characteristics of a TWT for materials processing applications and how those requirements affect the TWT's design are discussed. Comments on the present product lines and areas of development for all of the major TWT manufacturers are also presented. Finally, the issue of the ultimate potential cost of TWTs designed for microwave processing applications is addressed.

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Journal articles on the topic 'Traveling-wave Tube (TWT)'

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