RESUMEN
In this letter, a 263 GHz traveling wave tube for electron paramagnetic resonance spectroscopy is designed, fabricated and tested. A periodic permanent magnet focused pencil beam electron optical system is adopted. A folded waveguide slow-wave structure with modified serpentine bends is optimized to provide high-power wideband performance and stable operation. An experiment has been performed to verify the analysis results and confirm the amplifier stability. The device provides a maximum 11.9 W saturation output power and 25.5 dB saturation gain. Although the available solid-state signal source is unable to drive the amplifier to saturation beyond 260 - 264 GHz, 10 W output power over 5.6 GHz bandwidth has been measured.
RESUMEN
The application of radio frequency (RF) vacuum electronics for the betterment of the human condition began soon after the invention of the first vacuum tubes in the 1920s and has not stopped since. Today, microwave vacuum devices are powering important applications in health treatment, material and biological science, wireless communication-terrestrial and space, Earth environment remote sensing, and the promise of safe, reliable, and inexhaustible energy. This article highlights some of the exciting application frontiers of vacuum electronics.
RESUMEN
Nanoscale vacuum channel triodes realize the vacuum-like transmission of electrons in the atmosphere because the transmission distance is less than the mean free path of electrons in air. This new hybrid device is the deep integration of vacuum electronics technology, micro-nano electronics technology, and optoelectronic technology. It has the advantages of both vacuum and solid-state devices and is considered to be the next generation of vacuum electronic devices. In this work, vertical nanoscale vacuum channel diodes and triodes with edge emission were fabricated using advanced micro-nano processing technology. The device materials were all based on the vacuum electronics material system. The field emission characteristics of the devices were investigated. The diode continued emitting at a bias voltage from 0 to 50 V without failure, and the current variation under different vacuum degrees was better than 2.1%. The field emission characteristics of the devices were evaluated over a wide pressure range of between 10-7 Pa and 105 Pa, and the results could explain the vacuum-like behavior of the devices when operating in air. The current variation of the triode is better than 6.1% at Vg = 8 V and Va = 10 V.
RESUMEN
This paper researches the fabrication of a WR2.8 terahertz rectangular waveguide operating at the frequency ranging from 260 GHz to 400 GHz via UV-LIGA technology (UV-lithography, electroplating, and molding). In the process, megasonic agitation is applied to improve the mechanical properties and internal surface roughness of the WR2.8 rectangular waveguide. The effects of process parameters on the properties of structures are discussed, and optimized parameters are obtained to achieve accurate geometry dimensions. In addition, the highly crosslinked SU-8 is reliably removed from structures without damage through a synthesis method. The accuracy of the height and width of the WR2.8 rectangular waveguide is 5 µm and 2 µm, respectively, and the measured internal surface roughness is 79.6 nm. Moreover, experimental measurements and numerical simulations of the waveguide are conducted, and the difference between the two is also highlighted.
RESUMEN
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.