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This paper presents the preliminary results of using silicon nanowires for the fabrication of electron detectors suitable for scanning electron microscopy. The rather small size of the device allows its location just close to the specimen, hence increasing the detected current with no need to a complex optical device. The results of material variation as well as preliminary results of morphology changes...
A novel method for calculation of energy dependence of a secondary electron emission yield for different incidence angles is proposed. The model is based on the semi-empirical law for secondary electron yield and a Monte Carlo simulation of reflected primary energy. Initial tests show good agreement between the model and the experiment.
A good quality graphene is transferred onto honeycomb-like CNTs arrays with inner supporting CNTs. The efficient field emission is demonstrated due to a high aspect ratio protrusions and graphene crack edges. A high efficient current density about 1.2 mA/cm2 at threshold electric field of 7.8 V/μm with a turn-on electric field of 1.8 V/μm at the current density of 10 μA/cm2 is observed due to high...
Some technical problems were found during the testing and the application of the C-band MBK. These problems include the variation of power-frequency characteristics; the oscillation of high order modes; the breakdown in the electron gun and the microwave leak at the collector insulator. These technical problems were caused by the evaporation of the cathode, attenuating material and the copper, or...
The problems of designing reversible magnetic focusing systems of multi-beam klystrons are considered. The possible constructive decisions of magnetic systems are presented. Here are discussed the approaches to designing MRFS, techniques of magnetization and setting of the magnets, reducing the radial component of the magnetic induction on the axis of the working channels, materials selection of permanent...
Technological and design parts of plasma spraying metal-porous cathodes manufacturing for high-power multi-beam klystron are presented. The samples of cathode assemblies and their parameters are shown when operating in real devices. The results of investigations of the cathodes emission properties in the forced temperature conditions are presented in order to determine the maximum current density...
Efforts are continuing to improve the quality of controlled porosity reservoir cathodes and measure performance. CPR cathodes are being incorporated into several new configurations, including a magnetron injection gun, 15-beam klystron, and a Pierce gun for a 50 MW X-Band klystron. Improved computational tools assist users in CPR cathode design.
Method of obtaining sintered and pressed composed materials based on BaxSr1−xHfO3, where x = 0.25, 0.50, 0.75, with 16, 20, 24, 60 % W (by mass), and experimental results of thermionic properties investigations of these materials are represented. The composition of 80% Ba0.75Sr0.25HfO3 — 20% W (by mass) is characterized by the thermionic current density of 1014 A/cm2 at T = 1620 K.
A design of CW 1W 0.14THz folded waveguide TWT is investigated. The electron beam tube is manufactured, and beam transmission of 82% for a 14.8mA beam at 21.5kV. The RF coupling system and attenuator are manufactured and tested. The test results showed good performance that can meet the practical requirements in folded waveguide TWT. The first prototype has been built. Latest test results will be...
Over the years, issues with the supply of Beryllium, Beryllium Oxide, Thoriated-Tungsten wire, Rare-earth metals for magnets (Samarium-Cobalt), Tungsten, and recently Tungsten-Rhenium wire have put the supply of Microwave Tubes at risk. These Diminishing Manufacturing Source and Material Source (DMSMS) issues continue to be addressed by the Microwave Tube industry and with the help of US government...
The influence of the incident angle on Total Emission Electron Yield (TEEY) was experimentally investigated on technical silver. The increase of the TEEY with incidence angle, which strongly depends on the incident energy, was observed. The experimental observations generally agree with the new model presented in this conference.
This paper presents the latest results from a second harmonic gyro-TWA experiment at Strathclyde University. The experiment uses a helically corrugated interaction region and operates at Ka-band. Simulations have been performed to predict the amplifier gain and bandwidth using linear theory. Amplifier stability margin can be improved with the addition of a sever. A sever has been designed and manufactured,...
We offer to use slow-wave structures (SWSs) for monitoring parameters of absorbing coatings, which are widely used for stealth technology. It is shown that resonant frequencies and Q-factor of a SWS section placed in parallel to a monitored coating strongly depend on the electric and magnetic properties of the coating, that dependence can be converted in the coating's parameters reading.
LaB6 cathode is the emitter of choice in electron beam lithography tools. In commercial LaB6 cathodes, the (100) crystalline plane is used as the emissive surface. Values of (100) and surrounding crystalline planes workfunction (WF) vary widely in literature1. We have devised and implemented a simple, robust technique for evaluating LaB6 cathode workfunction.
Contact problems account for 40 percent of all electrical/electronic failures, ranging from small scale consumer electronic devices to large scale military and aerospace systems. This paper summarizes recent development on the theory of bulk contact and thin-film contacts, whose contact members may possess vastly different electrical resistivities. Current crowding at the rim of an electrode, scaling...
The w-band sapphire pillbox window had been designed in the article, with a bandwidth larger than 4GHz while VSWR less than 1.2. Structural parameters' effects on the bandwidth were analyzed and a relatively realizable assembling and welding structure was given out.
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