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In this paper, we report on the development of a prototype of 500W Ka-Band Helix TWTs. Based on the length and frequency of start oscillation calculated, a phase velocity taper is designed to suppress backward-wave oscillation and improve electronic efficiency of the TWT. The testing results show that this device is capable to deliver more than 500W (pulsed) power with a gain of 39dB over a bandwidth...
In this paper, two designs of helix slow-wave structures are proposed for kilowatt millimeter wave helix TWT. In order to suppress backward-wave oscillation, methods of pitch tapering and multi-sever have been used. Electron-wave interaction simulation has been carried out using PIC. According to the results, both of the two designs can produce over 1100 W output power in working band of 27∼31 GHz...
A challenge of high-power millimeter wave TWT is to realize high-power operation without incurring oscillation from backward-wave (BW) interaction. In this paper, the influences of beam parameters such as voltage, current and radius and helix structure parameters of pitch profile on BW oscillation are investigated. In order to get 500W output power, above 12% electron efficiency is considered and...
Controlling the methanol concentration is a key factor in improving the efficiency of the direct methanol fuel cell. In this study, the immersed-type Love mode sensor based on SiO2/ST-cut Y-propagation quartz was fabricated for monitoring the methanol concentration. A temperature controlled measurement system consisting of a spectrum analyzer and an oscillator circuit was employed to characterize...
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