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Vacuum Electronic Devices(VEDs) will continue to be the enabling technology for all kinds of vacuum electronic microwave sources with the most demanding specifications for use in both military and commercial systems. Vacuum-electronics technology is both old and new which is still evolving with inventions that take advantage of new materials, new interaction structures, and approaches to achieve record...
This paper introduces the design method and experiment of intensive beam electron optics which contains an electron gun and a magnetic focusing system for a 220GHz folded waveguide TWT. Pierce type electron gun is used. The thermal initial velocity effects as well as the beam waist radius and gunshot distance are considered for the design of electron gun. The period permanent magnet (PPM) system which...
Compact traveling wave tubes (TWTs) operating at 220 GHz and 340 GHz respectively are being developed. The 220 GHz TWT is designed to produce 10 W output power and has achieved 0.2 W. The 340 GHz TWT is designed to produce 1 W output power and has not been demonstrated yet. This paper describes the development of the TWTs' components and some test results of two TWT prototypes.
A four channels Ka-band multi-in-multi-out (MIMO) integrated TWT was designed based on previous three channels Ku-band integrated TWT. This device integrates four helices in one periodical permanent magnet (PPM) system. Over 50W output power could be achieved for each channel with overall efficiency higher than 40%.
The goal of this research is to develop an instant turn-on X-ray tube with high speed response. The tube is expected to produce a micro-spot less than 0.5mm at a voltage of 40kV and a current of 1mA. By CST simulation, the X-ray tube based on gate controlled carbon nanotube cathode was designed. Preliminary researches were carried out on carbon nanotube cathode fabrication, metal mesh electrode machining,...
We report the design and simulation of a metamaterial microwave triple-band absorber for microstrip meander-line slow wave structure. The compact single unit cell consists of four reversed electric ring resonators and a metallic ground plane separated by a dielectric layer. Simulation results show that the absorber has three distinctive absorption peaks which can be used to absorb the back-wave in...
In this continuous wave W-band TWT, a phase velocity step-tapering folded waveguide circuit was used instead of the uniform interaction circuit to improve the electron efficiency. The optimized pitch profile was proposed. The first prototype tube was assembled and tested. The output power in the 4GHz bandwidth of W-band was above 55W with about 15% overall efficiency.
In this paper, we fabricate copper high frequency structures for a 220GHz TWT amplifier using UV LIGA technology. The two halves have been assembled and bonded. The measurement results of the folded waveguide circuit show that the attenuation factor of the circuit is 240 dB/m.
A compact folded waveguide traveling-wave tube (TWT) with PPM system operating at 220 GHz with 10 W of output power and 10 GHz bandwidth is being developed. This paper reports the test results of the latest prototype.
In this paper, a 50 watts level continuous-wave W-band TWT was designed in order to meet the high frequency wireless communication requirements. A two-step phase velocity tapering interaction circuit was designed to improve the electron efficiency which was about 6% within the working bandwidth. A two-stage depressed collector was also used to improve the spent beam energy recovery efficiency. The...
In order to improve the power capacity of W-band Travelling Wave Tube (TWT), this paper proposed an overmoded TWT interaction circuit. The mode selection and circuit design was presented. A mode converter was also designed to excite the higher interaction mode. The simulation results show that nearly 1 kilowatts power could be reached in W-band.
The elliptical electrode collector has much smaller height comparing to traditional one with same inner surface area. Quadrupole lens which focus high-energy particles very effectively was used on the first electrode of collector to compress the electron beam in one dimension. Based on the simulation, the elliptical electrode collector was manufactured and tested. Experiment results show that the...
In the past years, we have fabricated a number of diamond windows for TWTs ranging from W-band to 340 GHz. This paper describes recent progress in research and development of the TWT diamond window at Beijing Vacuum Electronics Research Institute (BVERI).
This paper introduced latest experiment results of integrated travelling wave tube (TWT) which aimed to explore the possibility of active phased array system using vacuum electronics devices. Some design considerations and results of slow wave structure, beam optics, focusing magnet, coupling window and depressed collector was introduced. The tube output over 90W output power among the frequency of...
In order to reuse the harmonic current in the spent beam of W-band TWT, we have proposed a novel device, which is a G-band 2nd harmonic amplifier with two output ports for W-band and G-band respectively. Based on the rectangular waveguide cutoff characteristic and iris coupling principle, this paper described a new type of power splitter to extract the 2nd harmonic signal in G-band from mixed fundamental...
Integrated TWT based on the multi-beams interaction in the limited space is proposed in this paper. Four channels integrated TWT's electron gun and the beam transmission of the tube is simulated by software opera-3D. The design has been a viable integrated TWT electron optical system solutions,and the electron gun statics fluent can reach at least 99%, which provides the foundation for the design...
According to the original design of 30W level W-band folded waveguide CW traveling wave tube (TWT), a step-tapering structure was at the end of the uniform interaction circuit to improve the electron efficiency. Compared two kinds of tapering circuit, the results indicate that both circuits could achieve over 40W power at 91GHz∼97GHz. The electron efficiency could be improved from 3% to 4%. A collector...
A folded waveguide traveling-wave tube (TWT) with PPM system operating at 220 GHz with 10 W of output power and 10 GHz bandwidth is being developed. This paper reports the status of fabrication and test.
Folded waveguide slow wave structure is broadly used in W-band TWTs due to some advantages of easy-fabrication compared to helix and coupled cavity circuit, all metal structure to stand with high dissipation power, relatively wide bandwidth characteristic and etc. Due to the low coupling impedance and high attenuation factor in W-band folded waveguide circuit, the efficiency of actual TWTs is very...
W-band pulsed TWT Amplifiers have been developed as transmitters for weather radar of cloud detection. The test results show that two amplifiers can reach over 100W output power at 10% duty cycle in the air cooling condition.
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